Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41396 Publications

Multi-sensor data fusion using deep learning for bulky waste image classification

Bihler, M.; Roming, L.; Jiang, Y.; Afifi, A. J.; Aderhold, J.; Čibiraitė-Lukenskienė, D.; Lorenz, S.; Gloaguen, R.; Gruna, R.; Heizmann, M.

Deep learning techniques are commonly utilized to tackle various computer vision problems, including recognition, segmentation, and classification from RGB images. With the availability of a diverse range of sensors, industry-specific datasets are acquired to address specific challenges. These collected datasets have varied modalities, indicating that the images possess distinct channel numbers and pixel values that have different interpretations. Implementing deep learning methods to attain optimal outcomes on such multimodal data is a complicated procedure. To enhance the performance of classification tasks in this scenario, one feasible approach is to employ a data fusion technique. Data fusion aims to use all the available information from all sensors and integrate them to obtain an optimal outcome. This paper investigates early fusion, intermediate fusion, and late fusion in deep learning models for bulky waste image classification. For training and evaluation of the models, a multimodal dataset is used. The dataset consists of RGB, hyperspectral Near Infrared (NIR), Thermography, and Terahertz images of bulky waste. The results of this work show that multimodal sensor fusion can enhance classification accuracy compared to a single-sensor approach for the used dataset. Hereby, late fusion performed the best with an accuracy of 0.921 compared to intermediate and early fusion, on our test data.

Keywords: multispectral data; data fusion; image classification; CNN; multi-stream model; intermediate fusion; late fusion; multi-sensor data; multimodal data

Permalink: https://www.hzdr.de/publications/Publ-38060
Publ.-Id: 38060


Multi-Sensor Characterization for an Improved Identification of Polymers in WEEE Recycling

de Lima Ribeiro, A.; Fuchs, M.; Lorenz, S.; Röder, C.; Heitmann, J.; Gloaguen, R.

Polymers represent around 25% of total waste from electronic and electric equipment. Any successful recycling process must ensure that polymer-specific functionalities are preserved, to avoid downcycling. This requires a precise characterization of particle compounds moving at high speeds on conveyor belts in processing plants. We present an investigation using imaging and point measurement spectral sensors on 23 polymers including ABS, PS, PC, PE-types, PP, PVC, PET-types, PMMA, and PTFE to assess their potential to perform under the operational conditions found in recycling facilities. The techniques applied include hyperspectral imaging sensors (HSI) to map reflectance in the visible to near infrared (VNIR), short-wave (SWIR) and mid-wave infrared (MWIR) as well as point Raman, FTIR and spectroradiometer instruments. We show that none of the sensors alone can identify all the compounds while meeting the industry operational requirements. HSI sensors successfully acquired simultaneous spatial and spectral information for certain polymer types. HSI, particularly the range between (1600–1900) nm, is suitable for specific identification of transparent and light-coloured (non-black) PC, PE-types, PP, PVC and PET-types plastics; HSI in the MWIR is able to resolve specific spectral features for certain PE-types, including black HDPE, and light-coloured ABS. Fast-acquisition Raman spectroscopy (down to 500 ms) enabled the identification of all polymers regardless their composition and presence of black pigments, however, it exhibited limited capacities in mapping applications. We therefore suggest a combination of both imaging and point measurements in a sequential design for enhanced robustness on industrial polymer identification.

Keywords: e-waste; electronic waste; plastics; sensor network; hyperspectral imaging sensors; raman spectroscopy

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38059
Publ.-Id: 38059


Structural and magnetic properties of thin cobalt films with mixed hcp and fcc phases

Patel, G. I.; Ganss, F.; Salikhov, R.; Stienen, S.; Fallarino, L.; Ehrler, R.; Gallardo, R. A.; Hellwig, O.; Lenz, K.; Lindner, J.

Cobalt is a magnetic material that finds extensive use in various applications, ranging from
magnetic storage to ultrafast spintronics. Usually, it exists in two phases with different crystal lattices, namely in
hexagonal close-packed (hcp) or face-centered cubic (fcc) structure. The crystal structure of Co films
significantly influences their magnetic and spintronic properties. We report on the thickness dependence of the
structural and magnetic properties of sputter-deposited Co on a Pt seed layer. It grows in an hcp lattice at low
thicknesses, while for thicker films, it becomes a mixed hcp-fcc phase due to a stacking fault progression along
the growth direction. The X-ray based reciprocal space map technique has been employed to distinguish and
confirm the presence of both phases. Moreover, the precise determination of Landé’s g-factor by ferromagnetic
resonance provides valuable insights into the structural properties. In our detailed experiments, we observe
that a structural variation results in a nonmonotonic variation of the magnetic anisotropy along the thickness.
The work offers information of great significance and insight for both fundamental physics and potential
applications of thin films with perpendicular magnetic anisotropy.

Keywords: Magnetic Anisotropy; Reciprocal Space Mapping; Ferromagnetic Resonance

  • Lecture (Conference)
    Magnetism and Magnetic Materials, 30.10.-03.11.2023, Hyatt Regency Dallas, Texas, USA

Permalink: https://www.hzdr.de/publications/Publ-38057
Publ.-Id: 38057


Influences of the wall distance and initial shape on the dynamic behaviors of near-wall bubbles

Yan, H.; Zhang, H.; Zhang, H.; Liao, Y.; Wu, D.; Liu, L.

The phenomenon of buoyancy-driven bubbles near a fluid‒solid interface is common in both natural settings and industrial processes, such as oil and gas exploration and production. The intricate dynamics of bubbles are profoundly shaped by their interactions with adjacent solid walls. In this study, a direct numerical simulation of bubbles rising near a wall is conducted using the volume of fluid method. The motion behavior and wake vortex structure of bubbles with three types of migration trajectories (linear, zigzag, and spiral) are analyzed. The influences of the initial shape and wall distance of the bubbles on their motion trajectory, rising velocity, and wake structure is investigated. The results show that the presence of a nearby wall obstructs the diffusion of eddies across a bubble surface, and the repulsive force induced by the wall increases as the distance between the bubble and the wall decreases. Remarkably, at a dimensionless wall distance of 0.6, a change in the lateral lift direction triggers a collision between a zigzagging bubble and the wall, consequently setting the bubble into a bouncing motion mode. In the case of spiral-moving bubbles, proximity to the wall enhances the likelihood of oscillations within the bubble's migration trajectory along the x-y plane while maintaining stability along the z-y plane. While variations in the initial aspect ratio of bubbles have marginal impacts on the migration paths of linear and zigzagging bubbles, the initial shape affects the migration trajectory of spiral bubbles to some extent. The bubble migration trajectory first experiences oscillations when the initial deformation reaches its maximum.

Keywords: Bubble; Wall effect; wall distance; initial shape; wake vortex structure

Permalink: https://www.hzdr.de/publications/Publ-38055
Publ.-Id: 38055


Surface Functionalization of Industrial Materials and its Influence on Oxygen Nucleation

Heinrich, J.; Schwarzenberger, K.; Yang, X.; Eckert, K.

Proton-exchange membrane (PEM) electrolysis is one of the mostly used principles for H2 generation. To increase its efficiency, an enhanced O2 separation in the anodic cycle is necessary to reduce overvoltage and improve cooling. In this work, we investigate the surface functionalization with direct laser interference pattering (DLIP) and plasma coating (PECVD) of Ti64 and polypropylene to tune the affinity of the nonpolar gas to the materials by varying the hydrophilicity/hydrophobicity. The water contact angle is used to characterize the wettability. It gradually increases after the DLIP due to the adsorption of carbon compounds from the environment [1]. We observed that the effect is highly dependent on the surrounding media and also is reversible. Our experimental findings are supported by XPS and confocal microscopy measurements. Since DLIP requires heat resistant materials, we further investigated low-pressure plasma coating. Via optical recording we analyse the influence of the wettability on the O2 nucleation and provide first insights on how the oxygen separation of the anodic cycle of PEM electrolysers can be tuned by surface functionalization.

Keywords: surface functionalization; wettability; oxygen; bubble nucleation

  • Lecture (Conference)
    9th Bubble and Drop Conference, 11.-16.06.2023, Lublin, Poland

Permalink: https://www.hzdr.de/publications/Publ-38054
Publ.-Id: 38054


EMFL - a Distributed User Facility

Wosnitza, J.

Abstract nicht vorgelegen

  • Invited lecture (Conferences)
    Regional Meeting on Research in High Magnetic Fields, 06.-08.09.2023, Prag, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-38053
Publ.-Id: 38053


Materials Research in High Magnetic Fields at the HLD

Wosnitza, J.

Abstract nicht vorgelegen

  • Invited lecture (Conferences)
    Magnetic Fields in Materials Research, 22.-24.05.2023, Wroclaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-38052
Publ.-Id: 38052


Linking Sn-Li-(W-Cu) mineralization to post-collapse caldera evolution through cassiterite LA-ICP-MS U-Pb geochronology

Leopardi, D.; Gerdes, A.; Albert, R.; Gutzmer, J.; Lehmann, B.; Burisch-Hassel, M.

The Sadisdorf Sn-Li-(W-Cu) prospect, eastern Erzgebirge/ Krušné hory, is one of several Sn-W vein- and greisen-style deposits that are associated to the Altenberg-Teplice Caldera (ATC) system. Cassiterite mineralization is hosted by greisen alteration and stockworks intimately related to the composite Sadisdorf leucogranitic porphyry as well as a NE-SW striking vein system. The latter appears spatially – and possibly also genetically - unrelated to the Sadisdorf leucogranitic porphyry. Here, we applied LA-ICP-MS U-Pb geochronology to 16 cassiterite samples from the Sadisdorf prospect in order to constrain the timing of ore formation in the regional context of the evolution of the ATC.

All cassiterite ages range between 315.1± 3.3 Ma and 311± 4.0 Ma site and overlap within uncertainty across the Sadisdorf prospect – irrespective of the style of mineralization. Their calculated weighted mean average ages for greisen / stockwork and vein-hosted mineralization are 313.07±0.56 Ma and 313.2±1.6 Ma, respectively. This suggests that cassiterite mineralization at Sadisdorf is related to one single magmatic-hydrothermal event, albeit possibly associated to two spatially separated magmatic centers.

The cassiterite ages also coincide with the intrusion age of several microgranitic and rhyolitic dikes (314-313 Ma) that were emplaced late during the collapse of the ATC. This relates Sn mineralization to the late stages of the caldera evolution and suggests that Sn mineralization in the eastern Erzgebirge occurred 5-12 Ma later than previously assumed. The occurrence of fertile intrusion during the late stages of a caldera evolution is documented elsewhere (e.g. Mt. Aetna, USA and Mt. Pleasant, Canada) and provides useful criteria for regional exploration targeting.

Keywords: Caldera; Lithium; Tin; U-Pb cassiterite; geochronology

  • Lecture (Conference)
    SEG Conference 2023, 26.-29.08.2023, London, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-38051
Publ.-Id: 38051


LA-ICP-MS U-Pb cassiterite age data of the Sadisdorf deposit link Sn-Li-(W-Cu) mineralization in the eastern Erzgebirge to the collapse of the Altenberg-Teplice Caldera

Leopardi, D.; Gerdes, A.; Albert, R.; Gutzmer, J.; Lehmann, B.; Burisch-Hassel, M.

The Sadisdorf Sn-Li-(W-Cu) prospect in the eastern Erzgebirge (Germany) comprises two distinct styles of magmatic-hydrothermal mineralization, namely greisen-type mineralization at the Kupfergrube site, and stockwork-type mineralization at both the Kupfergrube and the Zinnklüfte sites. Previously, these two sites were regarded as expressions of two temporally distinct mineralization events. In this study, this temporal relation was tested by LA-ICP-MS U-Pb data obtained for 16 cassiterite samples, including samples from both sites and styles of mineralization. All 16 samples define a narrow range of ages between 315.1 ± 1.7 / 3.3 Ma and 311 ± 3.1 / 4.0 Ma. All ages overlap within uncertainty, suggesting that mineralization across the Sadisdorf prospect is likely related to the same magmatic-hydrothermal event.
On the regional scale, the cassiterite ages suggest that Sn-Li mineralization is associated with late-stage felsic magmatism directly following the collapse (~314-313 Ma) of the Altenberg-Teplice Caldera. The cassiterite ages also overlap with garnet U-Pb LA-ICP-MS ages of Sn-rich skarn occurrences in the western Erzgebirge (e.g., Breitenbrunn, Antonsthal and Hämmerlein). This observation provides direct evidence that greisen and skarn-hosted Sn mineralization are related to the same period of magmatism. The data indicate that the majority of Sn-mineralization in the Erzgebirge formed after 318 Ma (likely between 318-310 Ma), challenging previous models which invoked an older suite of granites (326-318 Ma) as causative source intrusions.

Keywords: LA-ICP-MS; geochronology; U-Pb cassiterite; Tin; Lithium; Caldera

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38049
Publ.-Id: 38049


Data publication: A continuous multiphase model for liquid metal batteries

Godinez-Brizuela, O. E.; Duczek, C.; Weber, N.; Nash, W.; Sarma, M.; Einarsrud, K. E.

Cycling data for experiment 3: Raw data, processed data and figures.

Keywords: liquid metal battery; energy storage; multiphase flow; Na-Zn

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Permalink: https://www.hzdr.de/publications/Publ-38048
Publ.-Id: 38048


Selected case studies on the bioremediation of uranium-contaminated (mine) waters

Raff, J.; Krawczyk-Bärsch, E.; Hilpmann, S.; Wollenberg, A.; Günther, A.; Klotzsche, M.; Steudtner, R.; Drobot, B.

The aim of the lecture is to give an overview of the equipment at the Institute of Resource Ecology and what analytical options this includes. Furthermore, current research work is presented in the context of the remediation of contaminated water and soil. Building on this, the potential and limits of biological processes and possibilities for collaboration will be shown.

Keywords: Bacteria; Fungi; Plants; Uranium accumulation; Uranium reduction

Related publications

  • Invited lecture (Conferences)
    Interregional Training Course on Environmental Remediation Design and Implementation, 27.11.-01.12.2023, Nanchang, China

Permalink: https://www.hzdr.de/publications/Publ-38046
Publ.-Id: 38046


Magnetic Properties of Actinide 2-Pyridone Complexes

Grödler, D.; Kaden, P.; Stumpf, T.; Gericke, R.

The anionic form of 2-pyridone (2-pyridyloxy; PyO) has proven to be a useful ligand for the synthesis of heterobimetallic complexes and thus supporting bonds between transitions metals (TM) and/or main-group elements. However, this chemistry has so far been limited to these groups, although interesting coordination motifs can be expected especially with actinides. Together with the high coordination numbers and various oxidation states, actinide 2-pyridyloxy complexes would have the necessary flexibility to bind a variety of transition metals.
Initially, we were interested in binding modes of 2-pyridone towards Th(IV) and U(IV). We have synthesized and characterized a series of heteroleptic actinide 2-pyridone complexes [AnCl₄(HPyO)₂], [ThCl₄(HPyO)₄], [AnX₂(HPyO)₆]X₂ and [AnCl(HPyO)₇]Cl₃ starting from [AnX₄(THF)₃] (An = Th, U; X = Cl, Br) and various equivalents of HPyO (2-7 equiv.). In addition, recent results show that Cu(I) is a suitable transition metal to realize heterobimetallic An-TM complexes.

Keywords: heterobimetallic; nuclear magnetic resonance spectroscopy; SQUID; single crystal X-ray diffraction

  • Poster
    2023 HZDR Science Conference, 15.-16.11.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38045
Publ.-Id: 38045


Fundamentals and concepts for the bioremediation of contaminated sites and water

Raff, J.

The presentation gives an overview of the different microbial diets and how plants, fungi and bacteria can be used for the bioremediation of uranium contaminated sites and waters. In particular, the advantages and disadvantages of the various approaches are named and a recommendation is given.

Keywords: Bioremediation; Uranium mining; Microbial metabolism

  • Invited lecture (Conferences)
    Interregional Training Course on Environmental Remediation Design and Implementation., 27.11.-01.12.2023, Nanchang, China

Permalink: https://www.hzdr.de/publications/Publ-38044
Publ.-Id: 38044


Heteroleptic Actinide 2-Pyridone Complexes

Grödler, D.; Kaden, P.; Stumpf, T.; Gericke, R.

The anionic form of 2-pyridone (2-pyridyloxy; PyO) has proven to be a useful ligand for the synthesis of heterobimetallic complexes and thus supporting bonds between transitions metals (TM) and/or main-group elements. However, this chemistry has so far been limited to these groups, although interesting coordination motifs can be expected especially with actinides. Together with the high coordination numbers and various oxidation states, actinide 2-pyridyloxy complexes would have the necessary flexibility to bind a variety of transition metals.

Keywords: heterobimetallic; nuclear magnetic resonance spectroscopy; single crystal X-ray diffraction

  • Poster
    Projektstatusgespräch 2023 zu BMUV-geförderten FuE-Projekten zur Entsorgung radioaktiver Abfälle, 06.-07.11.2023, Karlsruhe, Germany

Permalink: https://www.hzdr.de/publications/Publ-38043
Publ.-Id: 38043


The Hexacoordinate Si Complex SiCl₄(4-Azidopyridine)₂—Crystallographic Characterization of Two Conformers and Probing the Influence of SiCl₄-Complexation on a Click Reaction with Phenylacetylen

Riedel, S.; Gerwig, M.; Gerlach, D.; Brendler, E.; Gericke, R.; Kroke, E.; Wagler, J.

4-Azidopyridine (1) and SiCl₄ react with the formation of the hexacoordinate silicon complex SiCl₄(4-azidopyridine)₂ (2). Upon dissolving in warm chloroform, the complex dissociates into the constituents 1 and SiCl₄ and forms back upon cooling. Depending on the cooling, two different crystalline modifications of 2 were obtained, which feature two different trans-conformers. Slow cooling to room temperature afforded conformer 2′, which features coplanar pyridine rings. Rapid cooling to −39 °C afforded crystals of conformer 2′′, in which the planes of the pyridine ligands are nearly orthogonal to one another. Whereas 2′ resembles the molecular arrangement of various other known SiX₄(pyridine)₂ (X = halide) complexes, 2′′ represents the first crystallographically confirmed example of a SiX₄(pyridine)₂ complex in this conformation. Conformers 2′ and 2′′ were studied with ¹³C and ²⁹Si solid state NMR spectroscopy. Their differences in ²⁹Si chemical shift anisotropy, as well as energetic differences, were further investigated with computational analyses. In spite of the similar stabilities of the two conformers as isolated molecules, the crystal packing of 2′′ is less stable, and its crystallization is interpreted as a kinetically controlled effect of seed formation. (3+2)-cycloaddition of 1 and phenylacetylene in toluene at 110 °C yields a mixture of 1-(4-pyridyl)-4-phenyl-1,2,3-triazole (1,4-3) and 1-(4-pyridyl)-5-phenyl-1,2,3-triazole (1,5-3) in approximate 1:2 molar ratio. The crystal structures of the two isomers were determined via X-ray diffraction. In chloroform (at 60 °C), this reaction is slow (less than 2% conversion within 4 h), but the presence of SiCl₄ enhanced the rate of the reaction slightly, and it shifted the triazole isomer ratio to ca. 1:6 in favor of 1,5-3.

Keywords: chemical shift anisotropy; (3+2)-cycloaddition; Hirshfeld surface analysis; hypercoordination; packing efficiency; polymorphism; silicon; triazole

Permalink: https://www.hzdr.de/publications/Publ-38042
Publ.-Id: 38042


Bridging scales to understand species spatial organization

Colombo, E. H.; Saraiva De Menezes, J. F.; Calabrese, J.

From data we first construct a Langevin equation to describe the movement of the individuals. The ctmm1 package can be used to extract the parameters behind intrinsic dynamics of each individual (potential, diffusion coefficient, etc.). However, individuals’ home-range (i.e. the area they occupy) are also shaped by its interaction with individual nearby. For that we need to resolve the forces felt by individuals during encounters2 and then scale-up their effects. This coarse-graining process generates a PDE for the temporal evolution of the occupancy probability of a given individual. This final equation, extracted from data, provides a data-driven description of the formation and maintenance of home-ranges.

Keywords: Animal movement; Home-range; Interactions

  • Poster
    Big data analytical methods for complex systems, 18.10.2023, Wroclaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-38041
Publ.-Id: 38041


Optimizing animal movement studies: developing an application to evaluate study design

Simoes Silva, I. M.; Fleming, C. H.; Noonan, M. J.; Fagan, W. F.; Calabrese, J.

The study of movement behavior and home range in animals is fundamental to understanding ecological dynamics, yet designing efficient tracking studies remains a challenge due to the lack of clear guidelines. To address this knowledge gap we created 'movedesign,' a user-friendly application that enables researchers to evaluate the precision of three commonly reported movement and spatial ecology estimates: home range area, speed, and distance traveled. Leveraging the 'ctmm' R package, our application employs autocorrelated kernel density estimators (AKDEs) and continuous-time speed and distance (CTSD) estimators, effectively addressing biases inherent in animal movement datasets. By evaluating the interplay between data resolution and battery life, 'movedesign' guides researchers in making informed decisions to achieve reliable estimates of home range and velocity while considering trade-offs. With broad applications for researchers and decision-makers, this tool empowers efficient deployment strategies, optimizing sampling design for insightful and robust outcomes in movement ecology studies.

Keywords: ecology; conservation; software development; experimental design; biologgers; GPS sampling; GPS tracking; simulations; home range; space use

  • Open Access Logo Lecture (Conference)
    HZDR Science Conference 2023, 15.-16.11.2023, Helmholtz-Zentrum Dresden-Rossendorf e. V., Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-38040
Publ.-Id: 38040


A material study on magnetocaloric liquefaction of hydrogen

Gottschall, T.

Es hat ein Abstrakt vorgelegen.

  • Lecture (Conference)
    MML Workshop, 27.-29.09.2023, Jena, Deutschland
  • Lecture (Conference)
    2023 MRS Spring Meeting & Exhibit, 10.-14.04.2023, San Francisco, USA

Permalink: https://www.hzdr.de/publications/Publ-38039
Publ.-Id: 38039


Structures and ore deposits in the Eastern Erzgebirge: Linking the mineral system with post-Variscan transtension

Cerny, J.; Thiele, S. T.; Guilcher, M.; Burisch-Hassel, M.; Gutzmer, J.

The Eastern Erzgebirge region is exceptionally well endowed in magmatic-hydrothermal ore deposits related to granitic magmatism following the Paleozoic Variscan Orogeny. The Elbe Shear Zone (ESZ) is a major geological structure that forms the prominent eastern border of the Erzgebirge. The ESZ separates the Erzgebirge from the Lausitz Block – the latter being poor in known magmatic-hydrothermal mineralizations. This raises the question about the possible role of the ESZ in the evolution of the Eastern Erzgebirge mineral systems.
The ESZ is well known to be a zone of long-lived (and still ongoing) tectonic activity with mostly dextral kinematics and a total of ~40–50 km offset. It has been subject to a complex interplay of late to post-Variscan tectonic, magmatic, and sedimentary processes, which have left a distinct signature in the magmatic and sedimentary rock record. At least two distinct trans-tensional events can be distinguished and attributed to the dextral activity on the ESZ. These are recorded by (1) the Meissen Massif, a complex intrusion that was emplaced at 330–320 Ma in a dilatational jog, and (2) the Döhlen Basin near Freital, the volcano-sedimentary infill of a small pull-apart basin with abundant ignimbrite/tuff units ranging in age from ~294–286 Ma. The latter evidences for tectonic reactivation along the ESZ and synchronous magmatic events.
These ages bracket a potentially extensive period of activity of the ESZ, supporting a potential for a spatio-temporal link between the ESZ and formation of the Tharandt and Altenberg-Teplice Calderas at ~315–310 Ma. The latter is well known to host a number of small granitic stocks with related Sn-Li-(W-Cu) mineralization. This contribution is a part of the “New Potential” project initiated by the State Geological Survey of Saxony, which deals with the exploration of new perspective areas in the Eastern Erzgebirge mountains. Here, we explore the link between this trans-tensional tectonics and granitic magma emplacement in the Eastern Erzgebirge to better understand the tectonic control on the associated magmatic mineral systems. Significantly, we find that zones of strain-transfer between NW–SE striking dextral strike-slip faults localize felsic magmatism, by accommodating intrusions and establishing favorable pathways to the lower crust through which melts can ascend.

Keywords: Transtension; Erzgebirge; Elbe shear zone; Post-Variscan intrusions; Dilatational jog

  • Lecture (others)
    Pre-Conference Field Trip FT02: Erzgebirge - The Ore Mountains of Saxony and Bohemia: Old District–New Opportunities - Sn, W, Li, Ag, Base Metals, 18.-24.08.2023, Freiberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-38036
Publ.-Id: 38036


DATIV-Dynamic Aerosol Transport for Indoor Ventilation with Smart Array of Particulate MAtter Sensors (SAPMAS)

Schunk, C.

DATIV is an open source, low cost, distributed, portable sensor system which incorporates cameras and particulate matter sensors (PMS). This system can employ multiple sensors simultaneously and can be remotely operated using a web based GUI.

Keywords: Raspberry Pi; Camera; Particulate Matter; SBC; Aerosol; Sensor; COVID-19; Wi-Fi; Ventilation

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Permalink: https://www.hzdr.de/publications/Publ-38035
Publ.-Id: 38035


Needs for a Comprehensive European Plan to Acquire and Curate Nuclear Data

Körner, G.-E.; Dimitriou, P.; Boeltzig, A.; Garbil, R.; Leray, S.; Lewitowicz, M.; Widmann, E.

A Consultant’s Meeting was held at the IAEA to discuss the needs for a comprehensive European plan to acquire and curate nuclear data. Participants representing nuclear data groups, the nuclear physics community (NuPECC), and the existing funding agency (EURATOM), reviewed the status of nuclear data curation in Europe, including coordination, funding, and capacity building. A summary of the discussions as well as the list of recommendations and actions are included in this report.

Keywords: Nuclear Data; IAEA Nuclear Data Section; INDC International Nuclear Data Committee

  • Open Access Logo Other report
    Vienna, Austria: IAEA International Atomic Energy Agency, 2023

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Permalink: https://www.hzdr.de/publications/Publ-38032
Publ.-Id: 38032


The world-class Schlema-Alberoda U-(Ag-Co-Ni) deposit (Germany): mineralogy and fluid characteristics

Guilcher, M.; Gutzmer, J.; Hiller, A.; Krause, J.; Blamey, N.; Härtel, B.; Burisch-Hassel, M.

The Schlema-Alberoda deposit represents one of the largest uranium deposits in Europe with uranium ores closely associated with native metal-arsenide mineralization. All mineralization styles occur in veins and stockwork zones that crosscut carbon-rich Devonian to Silurian metasediments and metabasites. This study investigates the native metal-arsenide veins in the district and provides an update on mineral paragenesis and novel fluid inclusion data. Native metal-arsenide mineralization occurs as vein-hosted ore shoots with native metals (Ag, Bi, As) and Co-Ni-Fe arsenides. Within the native metal-arsenide stage, five mineral associations are identified: (i) bismuth-skutterudite-safflorite, (ii) silver-rammelsbergite-skutterudite, (iii) arsenic-silver-loellingite, (iv) loellingite and (v) arsenic-sulfosalt-sulphide. Fluid inclusions measured in dolomite-ankerite that occur as gangue minerals have homogenization temperatures of ~115-150°C with fluid salinities of ~24.4-27.3 wt% (NaCl+CaCl2) eq. The spatial relationship between native metal-arsenide across the deposit and carbon-rich lithologies suggest reduction of the ore fluid as a decisive precipitation process. Microthermometric data indicate mixing of a sedimentary and a basement brine, which is also documented for other occurrences of native metal-arsenide mineralization across Europe that are all related to Mesozoic continental rifting.

Keywords: Cobalt; Uranium; Arsenide; Fluid inclusion; Microthermometry; Crush-fast scan gas mass spectrometry; Erzgebirge; Five-element mineralization

  • Lecture (Conference)
    17th SGA Biennial Meeting, 28.08.-01.09.2023, ETH Zürich, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-38028
Publ.-Id: 38028


Neues Potenzial project, first interim report

Cerny, J.; Guilcher, M.; Thiele, S. T.; Burisch-Hassel, M.; Gutzmer, J.

This document is the first internal report for the “Neues Potenzial” project in collaboration with the Sächsisches Landesamt für Umwelt, Landwirtschaft und Geologie (LfULG). This two-year project will develop a novel mineral systems model for the Eastern Erzgebirge (Germany) with a focus on magmatic-hydrothermal Li-Sn-W greisen, skarn and Ag-Pb-Zn vein-style mineralization related to late Variscan or post-orogenic granitoid intrusions. The results obtained will be used to constrain search space and to define exploration vectors for future mineral exploration in the Eastern Erzgebirge region.

  • Other report
    Freiberg: HZDR and LfULG, 2023
    49 Seiten

Permalink: https://www.hzdr.de/publications/Publ-38027
Publ.-Id: 38027


Magnetochiral effects in geometrically curved magnetic architectures

Volkov, O.

Symmetry effects are fundamental in condensed matter physics as they define not only interactions but also resulting responses for the intrinsic order parameter depending on its transformation properties with respect to the operations of space and time reversal. Magnetic materials or layer stacks with structural space inversion symmetry breaking obtained much research attention due to the appearance of chiral Dzyaloshinskii-Moriya interaction (DMI) [1,2]. The latter manifests itself in the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls), that are envisioned to be utilized for prospective spintronic devices. At present, tailoring magnetochirality is done by the selection of materials and adjustment of their composition. Alternatively, space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [3]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [4,5].
Recently, much attention was dedicated to the exchange interaction, which enables curvature-induced extrinsic DMI as was proposed theoretically and validated experimentally for the case of conventional achiral magnetic materials [6]. Here, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture. Using the full-scale simulation of the asymmetric nanodots we study how the vortex texture is changing with respect to the introduced sample asymmetry.

Reference list
1. I. Dzyaloshinsky, J. Phys. Chem. Solids 4 (1958), 241.
2. T. Moriya, Phys. Rev. Lett. 4 (1960), 228.
3. R. Hertel, SPIN 3 (2013), 1340009.
4. D. Makarov, et al., Adv. Mater. 34 (2021), 2101758.
5. D. D. Sheka, et al., Commun. Phys. 3 (2020), 128.
6. O. M. Volkov, et al., Phys. Rev. Lett. 123 (2019), 077201.

Keywords: Dzyaloshinskii-Moriya interaction; Non-local chirality breaking; Magnetic vortex; Micromagnetics

  • Invited lecture (Conferences) (Online presentation)
    NATO Advanced Research Workshop 2023, 25.-28.09.2023, Kyiv, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-38025
Publ.-Id: 38025


Local and non-local effects in curvilinear micromagnetism

Volkov, O.

Dzyaloshinskii-Moriya interaction, also known as an antisymmetric exchange interaction, is the main source of chiral symmetry breaking effects in micromagnetic systems [1]. The later manifests itself in magnetic materials and layer stacks with structural space inversion symmetry breaking, where it leads to the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls). Such textures potentially could be utilized for prospective spintronic devices as a bit carrier. Still, tailoring of magnetochirality is only done by the selection of materials and adjustment of their composition in layer stacks.
Alternatively, we demonstrate that space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [2]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [2,3]. Moreover, curvilinear geometry also leads to the appearance of non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [4]. Recently, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture [5]. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters.

References
[1] A. Fert, N. Reyren and V. Cros, Nature Reviews Materials 2, 17031 (2017).
[2] D. Makarov, O. M. Volkov, A. Kákay, O. V. Pylypovskyi, B. Budinská and O. V. Dobrovolskiy, Adv. Mater. 34, 2101758 (2021).
[3] O. M. Volkov, A. Kákay, F. Kronast, I. Mönch, M.-A. Mawass, J. Fassbender and D. Makarov, Phys. Rev. Lett. 123, 077201 (2019).
[4] D. D. Sheka, O. V. Pylypovskyi, P. Landeros, Y. Gaididei, A. Kákay and D. Makarov, Commun. Phys. 3, 128 (2020).
[5] O. M. Volkov, D. Wolf, O. V. Pylypovskyi, A. Kákay, D. D. Sheka, B. Büchner, J. Fassbender, A. Lubk and D. Makarov, Nat. Commun. 14, 1491 (2023).

Keywords: Dzyaloshinskii-Moriya interaction; Non-local chirality breaking; Curvilinear Magnetism; Micromagnetics; Magnetic vortex

  • Invited lecture (Conferences)
    ”Nanomaterials: Applications & Properties” (IEEE NAP) 2023, 11.-15.09.2023, Bratislava, Slovakia

Permalink: https://www.hzdr.de/publications/Publ-38024
Publ.-Id: 38024


Local and non-local chiral effects in curvilinear nanomagnets

Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.

Dzyaloshinskii-Moriya interaction, also known as an antisymmetric exchange interaction, is the main source of chiral symmetry breaking effects in micromagnetic systems [1]. The later manifests itself in magnetic materials and layer stacks with structural space inversion symmetry breaking, where it leads to the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls). Such textures potentially could be utilized for prospective spintronic devices as a bit carrier. Still, tailoring of magnetochirality is only done by the selection of materials and adjustment of their composition in layer stacks.
Alternatively, we demonstrate that space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [2]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [2,3]. Moreover, curvilinear geometry also leads to the appearance of non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [4]. Recently, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture [5]. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters.

References
[1] A. Fert, N. Reyren and V. Cros, Nature Reviews Materials 2, 17031 (2017).
[2] D. Makarov, O. M. Volkov, A. Kákay, O. V. Pylypovskyi, B. Budinská and O. V. Dobrovolskiy, Adv. Mater. 34, 2101758 (2021).
[3] O. M. Volkov, A. Kákay, F. Kronast, I. Mönch, M.-A. Mawass, J. Fassbender and D. Makarov, Phys. Rev. Lett. 123, 077201 (2019).
[4] D. D. Sheka, O. V. Pylypovskyi, P. Landeros, Y. Gaididei, A. Kákay and D. Makarov, Commun. Phys. 3, 128 (2020).
[5] O. M. Volkov, D. Wolf, O. V. Pylypovskyi, A. Kákay, D. D. Sheka, B. Büchner, J. Fassbender, A. Lubk and D. Makarov, Nat. Commun. 14, 1491 (2023).

Keywords: Dzyaloshinskii-Moriya interaction; Topological spin textures; Magnetic vortex; Curvilinear magnetism

  • Lecture (Conference)
    Joint Conference of the Italian and European Community of Condensed Matter Physics 2023, 04.-08.09.2023, Milan, Italy

Permalink: https://www.hzdr.de/publications/Publ-38023
Publ.-Id: 38023


Local and non-local chirality breaking effects in curvilinear nanoarchitectures

Volkov, O.

The main origin of the chiral symmetry breaking and, thus, for the magnetochiral effects in magnetic materials is associated with an antisymmetric exchange interaction, the intrinsic Dzyaloshinskii-Moriya interaction (DMI) [1,2]. The later manifests itself in magnetic materials or layer stacks with structural space inversion symmetry breaking. The DMI is responsible for the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls), that are envisioned to be utilized for prospective spintronic devices. At present, tailoring of magnetochirality is done by the selection of materials and adjustment of their composition.
Alternatively, we demonstrate that space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [3]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [4,5,6]. Moreover, curvilinear geometry also leads to the appearance of non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [5]. Recently, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters.

References
[1] I. Dzyaloshinsky, J. Phys. Chem. Solids 4 (1958), 241.
[2] T. Moriya, Phys. Rev. Lett. 4 (1960), 228.
[3] R. Hertel, SPIN 3 (2013), 1340009.
[4] D. Makarov, et al., Adv. Mater. 34 (2021), 2101758.
[5] D. D. Sheka, et al., Commun. Phys. 3 (2020), 128.
[6] O. M. Volkov, et al., Phys. Rev. Lett. 123 (2019), 077201.

Keywords: Dzyaloshinskii-Moriya interaction; Cuvilinear magnetism; 3D magnetic architectures; Micromagnetics; Magnetic vortex

  • Invited lecture (Conferences)
    The Joint European Magnetic Symposia 2023, 28.08.-01.09.2023, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-38022
Publ.-Id: 38022


Micromagnetic parameters and longitudinal relaxation in ultrathin asymmetrically sandwiched magnetic films

Volkov, O.; Yastremsky, I. A.; Pylypovskyi, O.; Kronast, F.; Abert, C.; Oliveros Mata, E. S.; Makushko, P.; Mawass, M.-A.; Kravchuk, V. P.; Sheka, D.; Ivanov, B. A.; Faßbender, J.; Makarov, D.

Ultrathin asymmetric magnetic films are a prominent material science platform, which combines unique magnetic and electronic properties enabling prospective memory and logic spin-orbitronic devices. Here, we present the quantification mechanism to distinguish all static and dynamic micromagnetic parameters of the layer stack based on magnetometry [1] and quasi-static morphology experiments on domain wall equilibrium tilts [2]. The DW damping is found to be about 0.1 [2] and it is demonstrated to arise from a longitudinal relaxation being dominant among transversal mechanisms for ultrathin films [3].

[1] I. A. Yastremsky et al., Phys. Rev. Appl. 12, 064038 (2019).
[2] O. M. Volkov et al., Phys. Rev. Appl. 15, 034038 (2021).
[3] I. A. Yastremsky et al., Phys. Rev. Appl. 17, L061002 (2022).

Keywords: Ultrathin asymmetric magnetic film; Domain wall; Spin-otbit torque; Micromagnetics

  • Lecture (Conference)
    86th Annual Conference of the DPG and DPG Spring Meeting, 20.-24.03.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38021
Publ.-Id: 38021


Chirality coupling in curvilinear nanoarchitectures

Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.

Symmetry effects are key building blocks of condensed matter physics as they define not only interactions but also resulting re- sponses for the intrinsic order parameter. Namely, in magnetism geometric curvature governs the appearance of chiral and anisotropic responses [1], that introduce a new toolbox to create artificial chi- ral nanostructures from achiral magnetic materials [2,3]. Here, we demonstrate both theoretically and experimentally the existence of non-local chiral effects in geometrically curved asymmetric permalloy caps with the vortex texture. We find that the equilibrium vortex core obtain bend and curling deformation, that are dependent on the geometric symmetries and magnetic texture parameters.
[1] D. D. Sheka et al., Comm. Phys. 3, 128 (2020).
[2] O. M. Volkov et al., Phys. Rev. Lett, 123, 077201 (2019).
[3] D. Makarov et al., Adv. Mater. 34, 2101758 (2022).

Keywords: Symmetry effects; Cuvilinear magnetism; Magnetic vortex; Micromagnetics

  • Lecture (Conference)
    86th Annual Conference of the DPG and DPG Spring Meeting, 20.-24.03.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-38020
Publ.-Id: 38020


Data publication: Ab initio insights on the ultrafast strong-field dynamics of anatase TiO2

Suma Balakrishnan, S. L.; Lokamani, M.; Ramakrishna, K.; Cangi, A.; Murali, D.; Posselt, M.; Assa Aravindh, S.

Data and input scripts of the project "Ab initio insights on the ultrafast strong-field dynamics of anatase TiO2".

Keywords: Density functional theory; Electron dynamics; Quantum systems; Thin films

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38018
Publ.-Id: 38018


Evolution of point defects in pulsed-laser-melted Ge1-xSnx probed by positron annihilation lifetime spectroscopy

Steuer, O.; Liedke, M. O.; Butterling, M.; Schwarz, D.; Schulze, J.; Li, Z.; Wagner, A.; Fischer, I. A.; Hübner, R.; Zhou, S.; Helm, M.; Cuniberti, G.; Georgiev, Y.; Prucnal, S.

Direct-band-gap Germanium-Tin alloys (Ge1-xSnx) with high carrier mobilities are promising materials for nano- and optoelectronics. The concentration of open volume defects in the alloy, such as Sn and Ge vacancies, influences the final device performance. In this article, we present an evaluation of the point defects in molecular-beam-epitaxy grown Ge1-xSnx films treated by post-growth nanosecond-range pulsed laser melting (PLM). Doppler broadening – variable energy positron annihilation spectroscopy and variable energy positron annihilation lifetime spectroscopy are used to investigate the defect nanostructure in the Ge1-xSnx films exposed to increasing laser energy density. The experimental results, supported with ATomic SUPerposition calculations, evidence that after PLM, the average size of the open volume defects increases, which represents a raise in concentration of vacancy agglomerations, but the overall defect density is reduced as a function of the PLM fluence. At the same time, the positron annihilation spectroscopy analysis provides information about dislocations and Ge vacancies decorated by Sn atoms. Moreover, it is shown that the PLM reduces the strain in the layer, while dislocations are responsible for trapping of Sn and formation of small Sn-rich-clusters.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-38017
Publ.-Id: 38017


Non-local chirality breaking in curvilinear nanoarchitectures

Volkov, O.; Wolf, D.; Pylypovskyi, O.; Kakay, A.; Sheka, D.; Büchner, B.; Faßbender, J.; Lubk, A.; Makarov, D.

Symmetry effects are fundamental in condensed matter physics as they define not only interactions but also resulting responses for the intrinsic order parameter depending on its transformation properties with respect to the operations of space and time reversal. Magnetic materials or layer stacks with structural space inversion symmetry breaking obtained much research attention due to the appearance of chiral Dzyaloshinskii-Moriya interaction (DMI) [1,2]. The latter manifests itself in the formation of non-trivial chiral and topological spin textures (e.g. skyrmions, bubbles, homochiral spirals and domain walls), that are envisioned to be utilized for prospective spintronic devices. At present, tailoring magnetochirality is done by the selection of materials and adjustment of their composition. Alternatively, space inversion symmetry breaking of the magnetic order parameter appears in geometrically curved systems [3]. In curvilinear ferromagnets, curvature governs the appearance of geometry-induced chiral and anisotropic responses, which introduce a new toolbox to create artificial chiral nanostructures from achiral magnetic materials suitable for the stabilization of non-trivial chiral textures [4,5].
Recently, much attention was dedicated to the exchange interaction, which enables curvature-induced extrinsic DMI as was proposed theoretically and validated experimentally for the case of conventional achiral magnetic materials [6]. Here, we demonstrate the existence of non-local chiral effects in geometrically curved asymmetric permalloy cap with the vortex texture. Using the full-scale simulation of the asymmetric nanodots we study how the vortex texture is changing with respect to the introduced sample asymmetry. We find that the equilibrium vortex core obtain both bend and curling deformation, that are dependent on the geometric symmetries and magnetic parameters. We relate the observed changes in the vortex string to the non-local chiral effects, that arise from the asymmetry of the top and bottom surfaces and existence of both in- and out-of-plane magnetization components of different parity with respect to the reflection procedure [5]. The obtained micromagnetic results were confirmed by magnetic imaging using transmission electron microscopy based electron holography for the asymmetric permalloy cap. These results will be discussed in the talk.
[1] I. Dzyaloshinsky, J. Phys. Chem. Solids 4 (1958), 241.
[2] T. Moriya, Phys. Rev. Lett. 4 (1960), 228.
[3] R. Hertel, SPIN 3 (2013), 1340009.
[4] D. Makarov, et al., Adv. Mater. 34 (2021), 2101758.
[5] D. D. Sheka, et al., Commun. Phys. 3 (2020), 128.
[6] O. M. Volkov, et al., Phys. Rev. Lett. 123 (2019), 077201.

Keywords: Symmetry effects; Non-local chirality breaking; Magnetic vortex; Micromagnetics

  • Lecture (Conference)
    4th IEEE International Conference on Advances in Magnetics, IEEE AIM 2023, 16.-21.01.2023, Moena, Italy

Permalink: https://www.hzdr.de/publications/Publ-38016
Publ.-Id: 38016


IAEA’s Coordinated Research Projects on Thermal Hydraulics of Fast Reactors

Morelová, N.; Kriventsev, V.; Sumner, T.; Moisseytsev, A.; Heidet, F.; Wootan, D. W.; Casella, A. M.; Nelson, J. V.; Piazza, I. D.; Hassan, H.; Lorusso, P.; Martelli, D.; Yang, X.; Wang, J.; Lu, D.; Zhang, D.; Gerschenfeld, A.; Kliem, S.; Fridman, E.; Rineiski, A.; Kumaresan, N.; Giannetti, F.; Petruzzi, A.; Tanaka, M.; Jeong, J.-H.; Hong, J.; Stempniewicz, M.; Tsaun, S.; Volkov, A.; Wallenius, J.; Fiorina, C.; Mikityuk, K.; Vaghetto, R.; Omotowa, O.; Kelly, J.; Lane, J.

A Coordinated Research Project on “Benchmark Analysis of FFTF Loss of Flow Without Scram Test” was launched by the International Atomic Energy Agency (IAEA) in 2018. A series of passive safety tests were conducted from 1980-1992 at the Fast Flux Test Facility (FFTF), 400 MW(th) liquid sodium cooled nuclear test reactor owned by U.S. Department of Energy (DOE) to demonstrate the potential of FFTF to survive severe accident initiators with no core damage. Amongst these tests was a series of Loss of Flow Without Scram (LOFWOS) tests from power levels up to 50%, also commonly referred to as Unprotected Loss of Flow (ULOF) tests, which were studied in the IAEA CRP. The data were provided by the Argonne National Laboratory (ANL) and Pacific Northwest National Laboratory (PNNL).

Another Research Coordinated Project on “Benchmark of Transition from Forced to Natural Circulation Experiment with Heavy Liquid Metal Loop” was launched by the IAEA in 2022. Three tests were conducted in 2017 to study the thermal-hydraulic behavior of a test fuel assembly cooled by lead-bismuth eutectic alloy during transition from forced to natural convection at the NACIE-UP facility at Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Italy. This project is the first IAEA CRP that is dedicated to the thermal hydraulics of lead and lead bismuth eutectic (LBE) technology.

The paper provides a general overview of the two CRPs within the framework of the IAEA activities on thermal hydraulics of fast reactors.

  • Contribution to proceedings
    30th International Conference on Nuclear Engineering (ICONE30), 21.-26.05.2023, Kyoto, Japan
    DOI: 10.1299/jsmeicone.2023.30.1632

Permalink: https://www.hzdr.de/publications/Publ-38015
Publ.-Id: 38015


Junctionless Nanowire Transistor: From Devices to Sensing Applications

Ghosh, S.; Khan, M. B.; Echresh, A.; Kentsch, U.; Prucnal, S.; Vardhan, V.; Biswas, S.; Hellebust, S.; Holmes, J.; Erbe, A.; Georgiev, Y.

Downscaling of complementary metal-oxide-semiconductor (CMOS) technology is fraught with difficulties. As a result, novel devices and circuits, sophisticated nanomaterials, and enhanced fabrication processes have become increasingly important in recent decades. Particularly, silicon nanowires have been employed effectively in innovative electronic devices, including sensors, solar cells and in logic circuitry. Due to their high surface to volume ratio, silicon nanowires have been demonstrated as energy efficient devices, which is the key for the next generation of information processing. Field-effect-transistors based on silicon nanowires have been extensively used for sensing applications since the compact nanoscale structures allow excellent regulation of electrostatic potential across the nanowire channel. One such nanowire concept is junctionless nanowire transistor (JNT). A JNT is a highly doped nanowire channel without p-n junctions, where the gate electrode regulates the flow of charge carriers. Silicon JNTs have shown excellent sensi tivity to record-low concentrations of the protein streptavidin in liquid phase. However, they have not yet been operated as gas sensors.
In this work, we report the fabrication and characterization of silicon-based JNT devices and their initial tests as gas sensors. Intrinsic silicon-on-insulator (SOI) substrates are ion-implanted with phosphorus (n-type) dopant. Millisecond range flash lamp annealing (FLA) is used for dopant activation and implantation defect healing. Top-down approach is carried out for nanowire fabrication using electron beam lithography patterning of the negative resist HSQ followed by reactive ion etching. Successive processes of rapid thermal oxidation, nitrogen purge step and forming gas annealing are performed to create SiO2 shell around the silicon nanowires. SiO2 thickness is controlled by optimizating the time and temperature in these steps. UV lithography and metal evaporation are employed to create 50 nm thick Nickel contacts to the nanowires. Electrical characterization of these JNTs is performed by back-gating the nanowires. Unipolar device behavior is observed . However, these characteristics are changed after contact annealing leading to the ambipolarity in the devices. Two such transfer characteristics of JNTs based on unpassivated nanowires and nanowires with 3 nm SiO2 shell. These devices exhibit an on/off ratio of ~10^6. To further investigate the ambipolar nature of the silicon JNTs, output characteristics are measured, which shows Schottky barrier-based behavior of the devices. Furthermore, van der Pauw and Hall Effect measurements are performed to determine their carrier concentration and hall mobility. Successive measurements of electrical characteristics of these devices are also performed in vacuum to compare them with the usual ambient measurements. Unfunctionalized JNTs are tested as sensors in purified air and NO2 atmosphere. These sensor tests exhibited characteristic shifts in the transfer curve and a systematic increase and decrease of p- and ntype current, respectively, under the influence of NO2. These tests confirmed the potential suitability of the ambipolar JNT as sensors in gaseous environment. Additionally, these devices will be functionalized and tested for electrical detection of atmospheric free radicals.

Related publications

  • Lecture (Conference)
    49th Micro and Nano Engineering Conference (MNE), 25.-28.09.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-38014
Publ.-Id: 38014


Ultrafast Optical Pump-probe of Magnetic Kagome Metals

Goncalves Faria, M. V.; Winnerl, S.; Pashkin, O.; Helm, M.; Uykur, E.

The Kagome lattice is a two-dimensional network of corner-sharing triangles that is known to combine linear bands hosting massless Dirac fermions and dispersionless flat bands featuring massive localized electrons, both arising due to its geometry. FeSn binary compounds and the RM$_6$Sn$_6$(R=Tb,Gd and Y) series are commonly studied magnetic Kagome metals, which possess different magnetic ground states and interlayer Kagome coupling. Several steady-state experimental techniques have been used to study the magnetic and electronic structure of these materials and the effects of magnetism on the band structure. However, the ultrafast dynamics and the interplay of these unusual features have not yet been widely explored in the scope of time-domain spectroscopy. Here we present temperature- and fluence-dependent carrier dynamics of various magnetic Kagome metals studied using the optical pump-probe technique. Distinct carrier relaxations have been observed, and they can be partially attributed to the simple two-temperature model, as these are highly metallic compounds.

Keywords: Kagome metals; Optical pump-probe spectroscopy

  • Contribution to proceedings
    International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 17.09.2023, Montreal, Canada
    DOI: 10.1109/IRMMW-THz57677.2023.10299354
  • Lecture (Conference)
    International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 17.09.2023, Montreal, Canada

Permalink: https://www.hzdr.de/publications/Publ-38012
Publ.-Id: 38012


Intrusion tip velocity controls the emplacement mechanism of sheet intrusions

Köpping, J.; Cruden, A. R.; Thiele, S. T.; Magee, C.; Bunger, A.

Space for intruding magma is created by elastic, viscous, and/or plastic deformation of
host rocks. Such deformation impacts the geometries of igneous intrusions, particularly
sills and dikes. For example, tapered intrusion tips indicate linear-elastic fracturing during
emplacement, whereas fluidization of host rocks has been linked to development of elongate
magma fingers with rounded tips. Although host rock fluidization has only been observed at
the lateral tips of magma fingers, it is assumed to occur at their leading edges (frontal tips)
and thereby control their propagation and geometry. Here, we present macro- and micro-
structural evidence of fluidized sedimentary host rock at the lateral tips of magma fingers
emanating from the Shonkin Sag laccolith (Montana, western United States), and we explore
whether fluidization could have occurred at their frontal tips. Specifically, we combine heat
diffusion modeling and fracture tip velocity estimates to show that: (1) low intrusion tip ve-
locities (≤10−5 m s−1) allow pore fluids ahead of the intrusion to reach temperatures sufficient
to cause fluidization, but (2) when tip velocities are high (∼0.01–1 m s−1), which is typical for
many sheet intrusions, fluidization ahead of propagating tips is inhibited. Our results suggest
that intrusion tip velocity (i.e., strain rate) is a first-order control on how rocks accommodate
magma. Spatially and temporally varying velocities of lateral and frontal tips suggest that
deformation mechanisms at these sites may be decoupled, meaning magma finger formation
may not require host rock fluidization. It is thus critical to consider strain rate and three-
dimensional intrusion geometry when inferring dominant magma emplacement mechanisms.

Downloads

Permalink: https://www.hzdr.de/publications/Publ-38011
Publ.-Id: 38011


Geometallurgy workshop @ UFMG

Pereira, L.

The field of automated mineralogy has largely contributed to our understanding of mineral processing. Lately, by evaluating the particle information collected with automated mineralogy using statistical learning methods, it became possible to quantify the process behaviour of individual particles with consideration to their size, shape, liberation, and mineral association. In this workshop, we explore the latest methods used to quantify the recoverability of individual particles and how their results can be used to better understand mineral processing.

Keywords: Froth flotation; Particle based modelling; Geometallurgy; Raw materials

  • Invited lecture (Conferences)
    Geometallurgy workshop @ UFMG, 24.11.2023, Belo Horizonte, Brazil

Permalink: https://www.hzdr.de/publications/Publ-38010
Publ.-Id: 38010


Froth flotation study of SEDEX and VMS Pb-Zn ores under different pulp temperature constraints

Pashkevich, D.; Duggal, A.; Pereira, L.; Waters, K. E.

Sphalerite flotation represents one of a few sulfide recovery systems that experience significant variations in seasonal performance. The correlation between temperature and plant performance is observable in several zinc mines across the world, where both too high and too low temperatures impact recovery and grade. Here, we study the rougher flotation performance of two lead-zinc ores, of distinct geological settings, under controlled temperature conditions. A central composite design of the experiment approach is used to also investigate the effect of different flotation modifiers, namely lime, copper sulfate pentahydrate, and zinc sulfate heptahydrate. Process performance is evaluated by means of flotation kinetics, bubble size distribution (top), concentrate grade, yield, and water recovery. Results indicate that temperature variations lead to changes in froth stability, where a more stable froth is observed at colder temperatures and leads to higher yield and water recovery – presumably explaining the lower concentrate grades observed industrially.

Keywords: Froth flotation; Temperature; SEDEX; VMS

  • Contribution to proceedings
    Flotation '23, 06.-09.11.2023, Cape Town, South Africa
    Proceedings of Flotation '23
  • Lecture (Conference)
    Flotation '23, 06.-09.11.2023, Cape Town, South Africa

Permalink: https://www.hzdr.de/publications/Publ-38009
Publ.-Id: 38009


An open-source laboratory assistant tailored for flotation test work

Pereira, L.; Ben Said, B.; Hassan, A.; Rau, F.; Hoang, D. H.; Rudolph, M.

The role of laboratory-scale flotation test work for improving process understanding is unquestionable. Yet, to a large extent, laboratory routines are not standardized and may lead to considerable human errors. Operators have to simultaneously perform multiple tasks, and most data generated is often not saved, or saved without a proper structure. Laboratory assistants can potentially be used to overcome these issues. Yet, most options available are either dedicated to other scientific fields or cannot be easily tailored for flotation test work. Besides, sensors compatible with these solutions are often costly. Here, we introduce an open-source laboratory assistant tailored for flotation test work, which provides not only guidance for users, but also collects and orderly saves information from a series of affordable sensors (e.g., froth camera, pH, temperature, Eh, etc.). Benefits of using the laboratory assistant are demonstrated on two case studies: a reagent- and a flotation cell hydrodynamics-specific investigation.

  • Poster
    Flotation '23, 06.-09.11.2023, Cape Town, South Africa

Permalink: https://www.hzdr.de/publications/Publ-38008
Publ.-Id: 38008


Structural transformations in few-layer MnPSe₃ stimulated by thermal annealing and electron irradiation

Storm, A.; Köster, J.; Ghorbani Asl, M.; Kretschmer, S.; Gorelik, T. E.; Krasheninnikov, A.; Kaiser, U.

Transition metal phosphorous trichalcogenides (TMPTs) are inorganic materials with exciting properties, such as inherent magnetism combined with the electronic band gap. Due to their layered structure, these materials can be exfoliated into ultra-thin sheets, which show properties different from their bulk counterparts. In this work, we present an experimental study supported by first-principles calculations focused on tuning the properties of freestanding few-layer MnPSe₃ by local structural transformations stimulated by electron beam irradiation and thermal annealing under high vacuum conditions in a transmission electron microscope (TEM). In both cases, we observe the emergence of α- or γ-MnSe crystal structures. Using different TEM methods, we systematically investigate the irradiation-induced structural modifications. The results are rationalized with the help of ab-initio calculations, which predict that the elastic knock-on threshold for removing selenium is significantly higher than that for phosphorus. Nevertheless, an increased sputtering rate of Se as compared to P was detected by complementary spectroscopic experiments in this ternary compound, which indicates that inelastic damage mechanisms and etching play the dominant role within the low-voltage region. Moreover, the locally formed MnSe phases arise after the complete degradation of the host MnPSe₃ structure. First-principles calculations predict that the electronic and magnetic properties of 2D MnSe structures depend on the crystal types, facets, that is orientation of the crystallographic planes of the parent bulk material, and crystallite thickness.

Keywords: two-dimensional materials; Transition metal phosphorous trichalcogenides; transmission electron microscope; first-principles calculations; magnetism

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  • Secondary publication expected from 18.12.2024

Permalink: https://www.hzdr.de/publications/Publ-38007
Publ.-Id: 38007


Data publication: Portable Droplet-Based Real-Time Monitoring of Pancreatic α-Amylase in Postoperative Patients

Zhao, X.; Kolbinger, F. R.; Distler, M.; Weitz, J.; Makarov, D.; Bachmann, M.; Baraban, L.

research data on amylase concentration detection (Pancreatic α-Amylase in Postoperative Patients) with millifluidic device and plate reader and their statistical analysis

Keywords: pancreatic surgery; postoperative pancreatic fistula; pancreatic α-amylase; droplet-based millifluidics; point-of-care diagnostics

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Permalink: https://www.hzdr.de/publications/Publ-38005
Publ.-Id: 38005


Where I am – Chemical microscopy of Eu(III)

Steudtner, R.; Klotzsche, M.; Vogel, M.; Stadler, J.; Drobot, B.

Linking microscopy and spectroscopy based on the correlative application of state of the art spectroscopic, microscopic and biochemical methods and equipment is inevitable in the modern time of f-element biochemistry. The aim of this work was the direct visualization and localization in combination with the chemical identification and characterization of f-elements, here Eu(III), interacting with biostructures.
Herein, we utilized chemical microscopy – a combination of light microscopy and high resolution luminescence spectroscopy [1] – in order to spatially resolve the Eu(III) species distribution in an artificial natural sample. In this proof-of-concept study, a ternary system consisting of Eu(III), calcite and the metal reducing bacterium Shewanella oneidensis MR-1 was employed to confirm the applicability of chemical microscopy for environmental samples. Subsequent luminescence spectroscopic mapping and data deconvolution by the means of non-negative iterative factor analysis (NIFA) [2] resulted in three distinct signal sets: one Raman (pure calcite) and two Eu(III) emission spectra. Luminescence species assigned to Eu(III), on the one hand, that has been complexed with biofilm extracellular DNA (magenta-colored - Figure 1) and, on the other hand, protein bonded Eu(III), depicted in green. These findings emphasize the strength of the described analytical technique and open the field for further studies applying Eu(III) as molecular probe in order to understand complex interaction pathways of lanthanides in the environment. The utilization of Eu(III) as a luminescent probe for chemical microscopy additionally revealed the microscopic distribution of the Eu(III) in roots, root cross sections and individual cells presented by several examples.

  • Poster
    11th International Conference on f-Elements, 22.-26.08.2023, Strasbourg, France

Permalink: https://www.hzdr.de/publications/Publ-38004
Publ.-Id: 38004


Radioökologische Forschung am HZDR – Spannend bis in die Haarspitzen!

Steudtner, R.; Drobot, B.; Cherkouk, A.; Sachs, S.; Raff, J.

In der Umwelt beeinflussen physikalische, chemische und biologische Prozesse das Wanderungsverhalten von langlebigen Radionukliden (RN). Ziel der Forschung der Abteilung Biogeochemie ist es, dominierende Prozesse der Wechselwirkung von Radionukliden in der Biosphäre einschließlich der Nahrungskette zu identifizieren, die Biochemie dieser Prozesse auf molekularer Ebene zu verstehen und ihre Relevanz für Radionuklidmigration und -transfer nicht nur in der Natur, sondern auch im Umfeld eines Endlagers für hochradioaktive Abfälle zuverlässiger abschätzen zu können.
Für den sensitiven Nachweis, die Identifikation des Chemismus sowie der Lokalisation von Radionukliden in verschiedenen biologischen Matrices und aquatischen Systemen nutzen wir eine Vielzahl von spektroskopischen und mikroskopischen Verfahren. Eine zentrale Rolle spielt dabei die Laser-induzierte Anregung der Lumineszenz von Actiniden und Lanthaniden, welche in Verbindung mit hochauflösender Mikroskopie die Beschreibung radioökologischer Prozesse in einer neuen Detailtiefe erlaubt. Mit dieser einzigartigen Kombination konnte zum Beispiel eine Actinid-induzierte Stressantwort bei Pflanzenzellen nachgewiesen, und die chemische Bindungsform von Uran in komplexen Umweltproben analysiert werden. Ein wichtiger Teilaspekt ist dabei außerdem die qualitative und quantitative Erfassung der chemo- und radiotoxischen Wirkung endlagerrelevanter als auch natürlich vorkommender Radionuklide (naturally occuring radioactive materials - NORM) in Organismen und ihre Zellen.
Weitere Arbeiten befassen sich aktuell mit der Fragestellung, wie sich eine Uranbelastung in der Umgebung von Goldminen auf die im Umland lebende Bevölkerung auswirkt. Dazu wird gegenwärtig in einem gemeinsamen Projekt mit dem VKTA und der Wismut GmbH der Schwermetallgehalt in Haarproben von Personen mittels massenspektrometrischer Methoden bestimmt und bewertet, die im Umland von Johannisburg und nahe des weltweit größten Goldvorkommens, der Witwatersrand-Lagerstätte, leben. Beim Abbau des begehrten Edelmetalls gelangt auch gesundheitsschädlicher, giftiger und radioaktiver Bergbauabfall als Nebenprodukt an die Oberfläche.
Die aufgeführten Beispiele belegen eindrücklich, wie wichtig es ist, das Verhalten von Radionukliden in der Umwelt zu erforschen, zu verstehen und vorhersagbar zu machen, um die Bevölkerung und Natur effektiv zu schützen.

  • Poster
    10. RCA Workshop, 12.-14.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38003
Publ.-Id: 38003


Portable Droplet-Based Real-Time Monitoring of Pancreatic α-Amylase in Postoperative Patients

Zhao, X.; Kolbinger, F. R.; Distler, M.; Weitz, J.; Makarov, D.; Bachmann, M.; Baraban, L.

Postoperative complications after pancreatic surgery are frequent and can be life-threatening. Current clinical diagnostic strategies involve time-consuming quantification of α-amylase activity in abdominal drain fluid, which is performed on the first and third postoperative day. The lack of real-time monitoring may delay adjustment of medical treatment upon complications and worsen prognosis for patients. We report a bedside portable droplet-based millifluidic device enabling real-time sensing of drain α-amylase activity for postoperative monitoring of patients undergoing pancreatic surgery. Here, a tiny amount of drain liquid of patient samples is continuously collected and co-encapsulated with a starch reagent in nanoliter-sized droplets to track the fluorescence intensity released upon reaction with α-amylase. Comparing the α-amylase levels of 32 patients, 97% of the results of the droplet-based millifluidic system matched the clinical data. Our method reduces the α-amylase assay duration to approximately three minutes with the limit of detection 7 nmol/s·L, enabling amylase activity monitoring at the bedside in clinical real-time. The presented droplet-based platform can be extended for analysis of different body fluids, diseases, and towards a broader range of biomarkers, including lipase, bilirubin, lactate, inflammation, or liquid biopsy markers, paving the way towards new standards in postoperative patient monitoring.

Keywords: pancreatic surgery; postoperative pancreatic fistula; pancreatic α-amylase; droplet-based millifluidics; point-of-care diagnostics

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Permalink: https://www.hzdr.de/publications/Publ-38002
Publ.-Id: 38002


Actinide-MOF chemistry and applications

Schmidt, M.; Lyu, K.; März, J.; Fichter, S.; Patzschke, M.; Kaden, P.

Actinide metal-organic frameworks (An-MOFs) have garnered considerable attention in recent years.1 Yet, this class of compounds remains understudied compared with their transition metal or lanthanide homologues and this, despite a wide range of interesting properties, which may be turned into promising applications, from radiation detection to tailor-made nuclear waste forms. Moreover, this novel group of metal-organic compounds allows for straightforward comparison with molecular complexes, which have been the target of fundamental studies in actinide science for some time.
We will discuss a series of isoreticular MOFs based on mononuclear An(IV) (Th, U, Np, Pu) primary building units in which each actinide is coordinated by six molecules of 9,10-anthracenedicarboxylic acid (ADC).2 This arrangement leads to an unusually large coordination number of 12 in icosahedral symmetry. Quantum chemical calculations indicate that this large coordination number is only feasible in the high-symmetry environment provided by the An-MOFs. Moreover, these MOFs not only demonstrate autoluminescence but also wide-bandgap (2.89 eV) semiconducting properties. In addition, we will present recent findings, illustrating how selective crystallization from mixed-metal solutions may present a viable pathway for the production of actinide waste forms from specialized waste streams. As an example we will present the formation of Th-MOFs containing isonicotinic acid linkers in the presence of a wide range of metals representative of fission products.3

REFERENCES
[1] K. Lv et al., Coord. Chem. Rev. 446, 214011 (2021) and references therein.
[2] K. Lv et al., J. Am. Chem. Soc. 144, 2879 (2022).
[3] K. Lv et al., ACS Mater. Lett. 5, 536 (2023).

Related publications

  • Lecture (Conference)
    Actinides, 04.-08.06.2023, Golden, CO, USA
  • Lecture (Conference)
    Journées des Actinides, 17.-21.04.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-38001
Publ.-Id: 38001


Lisbon Summer School - Mid-term check - Innovative Target Modules for FAP-Targeting UniCAR T therapy

Boutier, H.; Feldmann, A.; Rodrigues Loureiro, L. R.; Arndt, C.; Hoffmann, L.; Bachmann, M.

This presentation was given in Lisbon for the first OncoProTools Summer School.

Keywords: Summer School; OncoProTools

  • Lecture (others)
    Mid-Term Check - Lisbon - OncoProTools Summer School, 14.-15.09.2023, Lisbon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-38000
Publ.-Id: 38000


Thermoelectric Magnetohydrodynamic Control in Alloy Solidification

Kao, A.; Fan, X.; Shevchenko, N.; Tonry, C.; Soar, P.; Krastins, I.; Eckert, S.; Pericleous, K.; Lee, P. D.

Magnetic fields have been shown to have a significant effect during solidification in a wide range of conditions from the slow growth of traditional casting to the more rapid growth of Additive Manufacturing. An underlying phenomenon is Thermoelectric Magnetohydrodynamics (TEMHD), which, due to inherent thermal gradients, generate thermoelectric currents and ultimately a Lorentz force through interaction with the magnetic field. In casting this leads to inter-dendritic convective solute transport. This can be used to control freckle defect formation in the GaIn system, where the magnetic field can be used to reposition channel formation, introduce preferential growth of secondary arms, plume migration and complex grain boundary interactions. These mechanisms have been observed by X-ray synchrotron experiments and predicted by TESA (ThermoElectric Solidification Algorithm), a parallel Cellular Automata Lattice Boltzmann based numerical model.
In laser AM, melt pools are subject to large thermal gradients and consequently form relatively large thermoelectric currents. The system is highly dependent on the orientation and strength of the magnetic field with competition between Marangoni flow and TEMHD resulting in control of the depth, width and potential deflections of the melt pool. This leads to significant changes in the microstructure including modification to the melt pool boundary layer and epitaxial growth. The numerical predictions also compare favourably to X-ray synchrotron experiments.

Keywords: Magnetic fields; Alloy solidification; Additive Manufacturing; Thermoelectric Magnetohydrodynamics

  • Lecture (Conference)
    International scientific colloquium “Modelling for Materials Processing”, 18.-19.09.2023, Riga, Latvia

Permalink: https://www.hzdr.de/publications/Publ-37999
Publ.-Id: 37999


In-situ Measurements of Dendrite Tip Shape Selection in a Metallic Alloy

Neumann-Heyme, H.; Shevchenko, N.; Grenzer, J.; Eckert, K.; Beckermann, C.; Eckert, S.

The size and shape of the primary dendrite tips determine the principal length scale of the microstructure evolving during solidification of alloys. In-situ X-ray measurements of the tip shape in metals have been unsuccessful so far due to insufficient spatial resolution or high image noise. To overcome these limitations, high-resolution synchrotron radiography and advanced image processing techniques are applied to a thin sample of a solidifying Ga-35wt.%In alloy, as shown in Figure 1. Quantitative in-situ measurements are performed of the growth of dendrite tips during the fast initial transient and the subsequent steady growth period, with tip velocities ranging over almost two orders of magnitude. As shown in Figure 2, the value of the dendrite tip shape selection parameter is found to be σ^*=0.0768. According to microscopic solvability theory, this value suggests an interface energy anisotropy of ε_4=0.015 for the present Ga-In alloy. The non-axisymmetric dendrite tip shape amplitude coefficient is measured to be A_4≈0.004, which is in excellent agreement with the universal value previously established for dendrites.

Keywords: dendrite tip; In-situ Measurements; Ga - In alloys; Interface energy anisotropy

  • Invited lecture (Conferences)
    TMS 2023 Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig, 19.-23.03.2023, San Diego, California, USA

Permalink: https://www.hzdr.de/publications/Publ-37998
Publ.-Id: 37998


The impact of melt flow on solidification patterns in a ternary Ga-In-Bi alloy

Shevchenko, N.; Budenkova, O.; Chichignoud, G.; Eckert, S.

In situ X-ray observations are scarce for ternary and multi-component alloys. A Ga-In-Bi alloy is solidified in a Hele-Shaw cell under buoyancy-driven convection. A complex and strongly disoriented dendrite-type solid phase is formed that differs from a regular dendrite network. It is shown that primary arms of dendrites in a ternary system adapt their velocity to the local concentration ahead of their tips and change continuously or abruptly the growth direction. Some grains exhibit a morphology that is rather similar to the "seaweed" pattern. The appearance of seaweed grains is usually related to a solid/liquid interfacial energy. Further, we focus on the role of melt flow in transition from dendritic arrays to seaweed structures. In particular, it is shown that the splitting of a dendrite tip is preceded by the oscillation of the local intensity of the X-ray pattern which is related to the local concentration of the components.

Keywords: Ternary alloy; in situ X-ray imaging; solidification; seaweed pattern; melt convection

  • Lecture (Conference)
    TMS 2023 Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig, 19.-23.03.2023, San Diego, California, USA

Permalink: https://www.hzdr.de/publications/Publ-37997
Publ.-Id: 37997


Convolutional neural networks applied to quantify the process behaviour of complex individual particles in froth flotation

Pereira, L.; Avalos, S.; Li, T.; Ortiz, J.; Ballani, F.; Afifi, A. J. M.; Hassan, A.; Frenzel, M.; van den Boogaart, K. G.; Tolosana Delgado, R.

The field of automated mineralogy has largely contributed to our understanding of mineral processing. Lately, by evaluating the particle information collected with automated mineralogy using statistical learning methods, it became possible to quantify the process behaviour of individual particles with consideration to their size, shape, liberation, and mineral association. Yet, automated mineralogy still requires a large intervention from operators for constructing an ore-specific mineral list and performing a series of image processing tasks. Here, we propose a method to quantify the process behaviour of individual particles using convolutional neural networks on the raw data collected with automated mineralogy: backscattered electrons and characteristic X-Ray signals. The flotation of a complex copper porphyry ore is used as a case study. The accuracy of the method is compared to the current standard procedure: manually processing the automated mineralogy data followed by particle-based modelling with a logistic regression.

Keywords: raw materials; mineral processing; froth flotation; resource efficiency; convolutional neural networks

  • Contribution to proceedings
    Flotation '23, 06.-09.11.2023, Cape Town, South Africa
    Proceedings of Flotation '23
  • Lecture (Conference)
    Flotation '23, 06.-09.11.2023, Cape Town, South Africa

Permalink: https://www.hzdr.de/publications/Publ-37995
Publ.-Id: 37995


Multidimensional modelling of particle separation processes: an approach to highly increase the number of particle properties considered

Pereira, L.; Frenzel, M.; Tolosana Delgado, R.; Rudolph, M.

Two main approaches have been leading the latest contributions to the field of modelling particle separation processes: fundamental models that focus on the individual interactions taking place in a separation unit and empirical models that focus on the properties of individual particles (size, shape, and composition) and how they influence the separation process. Both these approaches have clear advantages and disadvantages. In this study we focus on the empirical approaches given their relevance to the raw materials field, where it is likely to encounter a large variation in particle properties, especially particle composition. Most importantly, the uniqueness of each particle in this field is expected to lead to a distinct process behaviour in a separation unit.
Tromp devised the partition curves, the first method to quantify particle behaviour in a separation process as a function of their properties. The latest developments in the field profited from the wealth of particle information provided by modern scanning electron microscope-based imaging techniques, which systematically quantifies, within a short time, a series of relevant particle properties – named here as particle data. These latest developments, however, require particles to be grouped into bins, and can only make use of up to ten particle properties. In this contribution, we present a strategy to fully benefit from the wealth of particle data, allowing to quantify the process behaviour of individual particles and to consider hundreds of particle properties. This strategy employs a regularized multinomial logistic regression, which is able to independently estimate the importance of different particle properties for the behaviour of a particle in a process and is sufficiently robust to deal with millions of particles. The relevance of the new strategy to the particle separation field is demonstrated here with a froth flotation experiment, where we highlight the effect of a particle size, shape, modal and surface composition to its overall behaviour in a flotation cell.

Keywords: raw materials; mineral processing; particle technology; resource efficiency

  • Lecture (Conference)
    PARTEC - International Congress on Particle Technology, 26.-28.09.2023, Nürnberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37994
Publ.-Id: 37994


All About Particles: Modelling Ore Behaviour in Mineral Processing

Pereira, L.; Schach, E.; Tolosana Delgado, R.; Frenzel, M.

Mineral processing encompasses the series of operations used to first liberate the valuable minerals in an ore by comminution, and then separate the resulting particles by means of their geometric, compositional, and physical properties. From a geometallurgical perspective, it is fundamental to understand how ore textures influence the generation of ore particles and their properties. This contribution outlines the processes used to generate and concentrate ore particles, and how these are commonly modelled. A case study illustrates the main ideas. Finally, a brief outlook on the most important research challenges remaining in this branch of geometallurgy is presented.

Keywords: raw materials; mineral processing; particle technology; resource efficiency

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Permalink: https://www.hzdr.de/publications/Publ-37993
Publ.-Id: 37993


Momentum spectrum of Schwinger pair production in four-dimensional e-dipole fields

Degli Esposti, G.; Torgrimsson, G.

We calculate the momentum spectrum of electron-positron pairs created via the Schwinger mechanism by a class of four-dimensional electromagnetic fields called e-dipole fields. To the best of our knowledge, this is the first time the momentum spectrum has been calculated for 4D, exact solutions to Maxwell’s equations. Moreover, these solutions give fields that are optimally focused, and are hence particularly relevant for future experiments. To achieve this we have developed a worldline instanton formalism where we separate the process into a formation and an acceleration region.

Permalink: https://www.hzdr.de/publications/Publ-37992
Publ.-Id: 37992


Efficient Near-Infrared Light-Emitting Diodes Based on CdHgSe Nanoplatelets

Prudnikau, A.; Roshan, H.; Paulus, F.; Martín-García, B.; Hübner, R.; Bahmani Jalali, H.; de Franco, M.; Prato, M.; Di Stasio, F.; Lesnyak, V.

Cadmium mercury selenide (CdHgSe) nanocrystals exhibit a unique combination of low-energy optical absorption and emission, which can be tuned from the visible to the infrared range through both quantum confinement and adjustment of their composition. Owing to this advantage, such nanocrystals have been studied as a promising narrow-band infrared light emitter. However, the electroluminescence of CdHgSe-based nanocrystals has remained largely unexplored, despite their potential for emitting light in the telecom wavelength range. Further benefits to their optical properties are expected from their shape control, in particular the formation of 2D nanocrystals, as well as from a proper design of their heterostructures. In this work, a colloidal synthesis of CdHgSe/ZnCdS core/shell nanoplatelets (NPLs) starting from CdSe template NPLs employing a cation exchange strategy is developed. The heterostructures synthesized exhibit photoluminescence that can be tuned from ≈1300 to 1500 nm. These near-infrared-active NPLs are employed in light-emitting diodes, demonstrating low turn-on voltage and high external quantum efficiency.

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Permalink: https://www.hzdr.de/publications/Publ-37991
Publ.-Id: 37991


Lewis Acid-Base Adducts of α-Amino Acid-Derived Silaheterocycles and N-Methylimidazole

Seidel, A.; Gericke, R.; Kutzner, B.; Wagler, J.

In chloroform solution, the reaction of bis(tert-butylamino)dimethylsilane ((tBuNH)₂SiMe₂) and an α-amino acid (α-amino isobutyric acid, H₂Aib; D-phenylglycine, H₂Phg; L-valine, H₂Val) in the presence of N-methylimidazole (NMI) gave rise to the formation of the pentacoordinate silicon complexes (Aib)SiMe₂-NMI, (Phg)SiMe₂-NMI and (Val)SiMe₂-NMI, respectively. Therein, the amino acid building block was a di-anionic bidentate chelator at the silicon atom. In solution, the complexes were involved in rapid coordination–dissociation equilibria between the pentacoordinate Si complex (e.g., (Aib)SiMe₂-NMI) and its constituents NMI and a five-membered silaheterocycle (e.g., (Aib)SiMe₂), as shown by ²⁹Si NMR spectroscopy. The energetics of the Lewis acid-base adduct formation and the competing solvation of the NMI molecule by chloroform were assessed with the aid of computational methods. In CDCl₃ solution, deuteration of the silaheterocycle NH group proceeded rapidly, with more than 50% conversion within two days. Upon cooling to -44 °C, the chloroform solvates of the adducts (Aib)SiMe₂-NMI and (Phg)SiMe₂-NMI crystallized from their parent solutions and allowed for their single-crystal X-ray diffraction analyses. In both cases, the Si atom was situated in a distorted trigonal bipyramidal coordination sphere with equatorial Si–C bonds and an equatorial Si–N bond (the one of the silaheterocycle). The axial positions were occupied by a carboxylate O atom of the silaheterocycle and the NMI ligand’s donor-N-atom.

Keywords: bidentate ligands; deuterium transfer; hypercoordination; quantum chemical calculations; silicon; X-ray diffraction

Permalink: https://www.hzdr.de/publications/Publ-37990
Publ.-Id: 37990


Effects of a horizontal magnetic field on the cross-sectional distribution of gas bubbles chain rising in a gallium alloy

Murakawa, H.; Maeda, S.; Eckert, S.

Understanding the behavior of rising bubbles in a liquid metal under the influence of a magnetic field (MF) is
crucial for optimizing continuous casting processes. The study experimentally investigated the effects of a hor-
izontal MF on the behavior of bubble chains in a gallium alloy. High-speed ultrasonic computed tomography was
used to measure the instantaneous bubble crossing positions in a cylindrical column with an inner diameter of 50
mm. With an increase in the MF strength, the oscillations of the bubbles were suppressed, resulting in the
crossing position being concentrated in a certain area of the cross-section. The fluctuations in the time intervals
of the chain bubbles decreased. These effects were more pronounced when the magnetic interaction parameter
(or Stuart number) was greater than 1. The distribution of bubbles in the direction perpendicular to the MF was
widespread slightly compared to that in the direction parallel to the MF; this was noticeable at higher flow rates.
The suppression of the wake turbulence induced by the Lorentz force was larger in the direction parallel to the
MF than that in the direction perpendicular to the MF. Our results have the potential to be used for the direct
verification of numerical models.

Keywords: liquid metal; bubbly flow; magnetic field; high-speed ultrasonic computed tomography

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  • Secondary publication expected from 31.10.2024

Permalink: https://www.hzdr.de/publications/Publ-37988
Publ.-Id: 37988


Vibrations Analysis of Bubble Evolution in Liquids of Varying Physical Properties

Rigas, K.; Willers, B.; Eckert, S.; Glaser, B.

In recent years there is an attempt to control the gas stirring intensity in metal-making ladles with the aid of vibration measurements. Understanding better the induced vibrations in two-phase flows can substantially improve the existing models for gas stirring control. In this work, highly sensitive accelerometers were used for the vibration measurements in a liquid metal alloy; Sn–40 wt pctBi alloy at 200 °C and water at 20 °C. The examination of the liquids was conducted in the ladle mockup integrated into the Liquid Metal Model for Steel Casting facility at Helmholtz-Zentrum Dresden Rossendorf. Single bubbles were generated in the respective
liquids by controlled argon injection at low flow rates in the range of 0.01 to 0.15 NL/min through a single nozzle installed at the bottom of the ladle. Obtained results demonstrate differences between the induced vibrations in the examined liquids in terms of the magnitude of the root mean square values of vibration amplitude and the shape of the resulting curves with increasing flow rate. Furthermore, continuous wavelet transform reveals variations in the duration and vibrational frequency of the evolved bubble phenomena. The findings suggest that
differences in the physical properties of the examined liquids result in variations in the vibrations induced during bubble evolution.

Keywords: steel ladle; gas stirring; bubbly flow; vibration measurements

Permalink: https://www.hzdr.de/publications/Publ-37987
Publ.-Id: 37987


New Insights in Controlling Freckle Defect Formation using Magnetic Fields

Fan, X.; Shevchenko, N.; Tonry, C.; Clark, S. J.; Atwood, R. C.; Eckert, S.; Pericleous, K.; Lee, P. D.; Kao, A.

Static magnetic fields have been shown to have a significant effect on channel formation in the GaIn freckle defect forming alloy. Inter-dendritic convective solute transport driven by the Thermoelectric Magnetoydrodynamics (TEMHD) phenomena leads to repositioning of the channel, preferential growth of secondary arms, plume migration and complex grain boundary interactions. This paper focuses on a secondary TEMHD mechanism that is generated by larger scale thermoelectric currents that circulate between the liquid and the entire mushy zone. This secondary mechanism is strongly dependent on the thermal profile and this leads to further modification of the bulk flow and ultimately plume migration. This mechanism has been observed by Xray synchrotron experiments and predicted by TESA (ThermoElectric Solidification Algorithm), a parallel Cellular Automata Lattice Boltzmann based numerical model, providing new insights into the intimate coupling between thermal solidification conditions and the effect of the magnetic field.

Keywords: Static magnetic fields; Solidification; Thermoelectric Magnetoydrodynamics; Freckle defect; Ga-In alloys

  • Lecture (Conference)
    TMS 2023 Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig, 19.-23.03.2023, San Diego, California, USA

Permalink: https://www.hzdr.de/publications/Publ-37986
Publ.-Id: 37986


Structure prediction of iron hybrides at high pressures with machine-learned interactomic potentials

Tahmasbi, H.; Ramakrishna, K.; Lokamani, M.; Cangi, A.

Understanding the composition of Earth’s core and mantle is a major challenge in geoscience and materials science. The core is primarily made of iron, but its density is known to be slightly lower than pure iron. Hydrogen contributes to this density deficit, leading to significant interest in the properties and structure of iron hydrides under high pressure.
Previous studies have shown that the dhcp phase of FeH remains stable at lower pressures (10-40 GPa) but undergoes phase transitions to hcp and fcc phases at higher pressures. This study focuses on a theoretical exploration of the potential energy surfaces (PESs) of FeH under varying pressure conditions. The objective is to demonstrate the effectiveness of automated
and systematic methods for training and validating transferable machine-learned interatomic potential (ML-IAP) using global optimization techniques. Utilizing this potential, which significantly reduces computational costs, the phase diagram of the stoichiometric Fe-H system is analyzed across a range of pressures.
To achieve this, we utilize the PyFLAME code to construct a highly transferable ML-IAP. With this accurate potential, the PESs of bulk FeH structures are systematically investigated through global sampling using the minima hopping method. This comprehensive exploration enables the prediction of stable and metastable iron hydrides from 0 to 100 GPa. Density functional theory calculations are conducted to refine the predicted structures and evaluate their dynamical stability. The findings of this study reveal a wide range of novel low-energy polymorphs of FeH at each pressure level, alongside the recovery of well-known structures in the literature.

  • Poster
    Polish-German WE-Heraeus Seminar & Max Born Symposium, 03.-06.12.2023, Goerlitz, Germany

Permalink: https://www.hzdr.de/publications/Publ-37985
Publ.-Id: 37985


Temperature-Dependent Pump-Probe Spectroscopy of the Magetic Kagome Metal Fe3Sn2

Goncalves Faria, M. V.; Wang, Q.; Lei, H. C.; Pashkin, O.; Winnerl, S.; Helm, M.; Uykur, E.

In this study, we present optical pump-probe measurements on a magnetic kagome metal, Fe3Sn2, under different temperatures down to 10 K. The obtained spectra can be fitted with a double exponential decay, indicating that the system has two distinct relaxation processes. Additionally, some unexpected and pronounced oscillations are dominating the spectra, giving evidence of a strong electron-phonon coupling in Fe3Sn2, at least in this ultra-fast regime. The frequency of this coupled phonon is determined to be around 2.5 THz. Finally, we will discuss the temperature and pump fluence dependence of the observed phonon coupling and the distinct relaxation dynamics in this material.

  • Lecture (Conference)
    Deutsche Physikalische Gesellschaft, 28.03.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37984
Publ.-Id: 37984


Manipulation of Encapsulated Plasmons in Solids for Photonic Applications

Li, R.; Pang, C.; Sun, X.; Jamshidi, K.; Zhou, S.; Chen, F.

Plasmonics offers a promising framework for next-generation photonic applications, including optical tweezers, ultrafast lasing, and quantum communication. Integrating plasmonics into photonics enables efficient interface coupling between heterogeneous systems, resulting in enhanced performance and diverse functionality. This review presents various unique encapsulation methods for developing plasmonics-embedded hybrid nanocomposite systems. Recent progress in the manipulation mechanisms of encapsulated plasmons is systematically summarized, offering an active modulation platform for optimizing optical performance. Considering the opportunities and challenges, the advancement of tunable encapsulated plasmons exhibits promising prospects, as demonstrated by a section discussing recent significant progress in photonic applications.

Keywords: Plasmonics; Nanostructures; Ion implantation; Optical tailoring; Integrated photonic application

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Permalink: https://www.hzdr.de/publications/Publ-37983
Publ.-Id: 37983


Fine-tuning of plasmonics by Au@AuY/Au core-shell nanoparticle monolayer for enhancement of third-order nonlinearity

Yong, L.; Pang, C.; Amekura, H.; Schumann, T.; Peng, L.; Zhixian, W.; Haocheng, L.; Li, R.

The manipulation of plasmonics on noble metal nanoparticles (NPs) is of great interest in developing nonlinear photonic devices, such as all-optical switches and frequency combs. An Au@AuY-core/Au-shell nanoparticle (Au@AuY/Au NP) monolayer is proposed for the fine-tuning of plasmonics and enhanced third-order nonlinearity. Based on the different thermodynamic mechanisms of Au and Y ions, the compact Au@AuY/Au core–shell architectures are designed and surface-modified in fused silica (SiO2) with enhanced free electron density, mobility, and quantum size effect. The flexible modulation of plasmonics is realized, resulting in significant absorption enhancement (165% for interband absorption and 38% for free electron absorption, respectively) and fine-tuning of the localized surface plasma resonance (LSPR) band. In addition, the physical mechanism is investigated by density functional theory (DFT) and Mie theory, which reveals a transition from size-independence to size-dependence of LSPR owing to the synergistic effect of multiple physical factors such as free electron density and mobility. With the above advantages, the third-order nonlinearity is enhanced by 4.4 times compared with traditional Au NPs. It indicates the significant potential of Au@AuY/Au core–shell NP monolayer in the performance improvement of nonlinear photonic devices.

Keywords: Plasmonics; Core-shell alloy nanostructure; Localized surface plasmon resonance; Third-order nonlinearity; Sequential ion implantation

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Permalink: https://www.hzdr.de/publications/Publ-37980
Publ.-Id: 37980


Coacervation-induced hydrodynamic instabilities in radial displacements

Stergiou, Y.; Perrakis, A.; Keshavarzi, B.; Eckert, K.; Schwarzenberger, K.

We investigated a miscible displacement of a less viscous liquid by a more viscous shear-thinning liquid in a Hele-Shaw cell. Due to a coacervation interaction between both liquids, a hydrodynamic instability appears in the form of inward viscous fingering. The liquids consisted of a solution of the anionic biopolymer xanthan gum, as the injection liquid, which displaced a cationic C14T AB aqueous solution. In the contact zone between the two solutions, the oppositely charged species form polymer-surfactant complexes due to electrostatic interactions. These complexes are insoluble in water and separate from the aqueous solution in the form of a gel-like growing membrane. During the continuing radial displacement, a large variety of patterns can emerge which is attributed to the rheological properties of the system involving viscosity gradients, the non-Newtonian nature of the displacing solution and the complex rheology of the coacervate phase. Variation of the flow rate and gap width of the Hele-Shaw cell revealed distinct instability regimes and allowed to identify main contributing mechanisms. These insights open the door for further investigation of fluid mechanics (i.e. Saffman-Taylor instability), pattern formation and self-organization problems in multiphase systems of complex rheology and its applications in engineering and technology.

  • Lecture (Conference)
    Dynamics Days Europe 2023, 06.09.2023, Napoli, Italia

Permalink: https://www.hzdr.de/publications/Publ-37979
Publ.-Id: 37979


Data publication: Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic Vortices

Iurchuk, V.; Sorokin, S.; Faßbender, J.; Lindner, J.; Kakay, A.

The archive contains the experimental (MR and EDFMR) and simulated (mumax3) data related to the publication "Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic Vortices" (Physical Review Applied 20(2023), 024080).

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Permalink: https://www.hzdr.de/publications/Publ-37978
Publ.-Id: 37978


Software: removal of bremsstrahlung background from SAXS signals with deep neural networks

Starke, S.; Smid, M.

Software for training and inference of neural network models to remove bremsstrahlung background from SAXS imaging data obtained at the European XFEL laboratory.

We thank Peter Steinbach for providing the codebase for the equivariant UNet, which we integrated into our repository.

Keywords: SAXS; XFEL; equivariant neural networks; noise removal

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Permalink: https://www.hzdr.de/publications/Publ-37977
Publ.-Id: 37977


Near-infrared photodetectors based on single germanium nanowires

Echresh, A.; Shaikh, M. S.; Helm, M.; Erbe, A.; Berencen, Y.; Rebohle, L.; Georgiev, Y.

Germanium (Ge) is a promising candidate for designing near-infrared photodetectors because of its bandgap (0.66 eV), which induces a large absorption coefficient at near-infrared wavelengths. Also, Ge has excellent compatibility of parallel processing with silicon technology [1,2]. Photodetectors based on Ge material have been fabricated with different structures such as metal-semiconductor-metal (MSM) and p−n junctions. On the other hand, the observation of high responsivity in semiconductor nanowires with a high surface-to-volume ratio has attracted growing interest in using nanowires in photodetectors. So far, significant efforts have been made to fabricate single nanowire-based photodetectors with different materials such as Si, Ge, and GaN to achieve miniaturized devices with high responsivity and short response time [3-5]. Hence, Ge nanowires are an excellent candidate to fabricate single nanowire-based near-infrared photodetectors.

In this work, we report on the fabrication and characterization of an axial p−n junction along Ge nanowires. First, through a resist mask created by electron beam lithography (EBL), the top Ge layers of germanium-on-insulator (GeOI) substrates were locally doped with phosphorus ions using ion beam implantation followed by rear-side flash lamp annealing. Then, the single Ge nanowire-based photodetectors containing an axial p−n junction were fabricated using EBL and inductively coupled plasma reactive ion etching. The fabricated single Ge nanowire devices demonstrate the rectifying current−voltage characteristic of a p−n diode in dark conditions. Moreover, the photoresponse of the axial p−n junction-based photodetectors was investigated under light illumination with three different wavelengths: 637 nm, 785 nm, and 1550 nm. The measurements indicated that the fabricated photodetectors can be operated at zero bias and room temperature under ambient conditions. A high responsivity of 3.7×102 AW-1 and a detectivity of 1.9×1013 cmHz1/2W-1 were observed at zero bias under illumination of a 785 nm laser diode. The responsivity of the single Ge NW photodetectors was increased by applying a reverse bias of 1V.

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  • Lecture (Conference)
    Micro and Nano Engineering (MNE) conference, 25.-28.09.2023, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-37976
Publ.-Id: 37976


Piezostrain as a Local Handle to Control Gyrotropic Dynamics of Magnetic Vortices

Iurchuk, V.; Sorokin, S.; Lindner, J.; Faßbender, J.; Kakay, A.

We present a study of the piezostrain-tunable gyrotropic dynamics in Co40Fe40B20 vortex microstructures fabricated on a 0.7Pb[Mg1/3Nb2/3]O3-0.3PbTiO3 single-crystal substrate. Using field-modulated-spin-rectification measurements, we demonstrate large frequency tunability (up to 45%) in individual microdisks accessed locally with low surface voltages, and magnetoresistive readout. With increased voltage applied to the substrate, we observe a gradual decrease of the vortex-core gyrotropic frequency associated with the contribution of the strain-induced magnetoelastic energy. The frequency tunability strongly depends on the disk size, with increased frequency downshift for disks with larger diameter. Micromagnetic simulations suggest that the observed size effects originate from the joint action of the strain-induced magnetoelastic and demagnetizing energies in large magnetic disks. These results enable a selective energy-efficient tuning of the vortex gyrotropic frequency in individual vortex-based oscillators with all-electrical operation.

Keywords: Magnetic vortices; Magnetoelastic effect; Magnetoresistance; Spin dynamics

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Permalink: https://www.hzdr.de/publications/Publ-37975
Publ.-Id: 37975


Probing shock dynamics inside micro-wire targets after high-intensity laser irradiation using small angle x-ray scattering of a free-electron laser

Kluge, T.; Bussmann, M.; Galtier, E.; Glenzer, S.; Grenzer, J.; Gutt, C.; Hartley, N. J.; Huang, L.; Laso García, A.; Ja Lee, H.; McBride, E. E.; Metzkes-Ng, J.; Nakatsutsumi, M.; Nam, I.; Pelka, A.; Prencipe, I.; Randolph, L.; Rehwald, M.; Rödel, C.; Rödel, M.; Toncian, T.; Yang, L.; Zeil, K.; Schramm, U.; Cowan, T.

In this paper, we present an experiment that explores the plasma dynamics of a 7 μm diameter carbon wire after being irradiated with a near-relativistic-intensity short pulse laser. Using an x-ray free electron laser pulse to measure the small angle x-ray scattering signal, we observe that the scattering surface is bent and prone to instability over tens of picoseconds. The dynamics of this process are consistent with the presence of a sharp, propagating shock front inside the wire, moving at a speed close to the hole boring velocity or that expected from a thermal shock at a few tens of Mbar.

Keywords: plasma; SAXS; XFEL; laser; proton acceleration

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Permalink: https://www.hzdr.de/publications/Publ-37974
Publ.-Id: 37974


QED.jl - A Strong-field particle physics ecosystem

Hernandez Acosta, U.

We present a novel approach for an event generator inherently using exact QED descriptions to predict the results of high-energy electron-photon scattering experiments that can be performed at modern X-ray laser facilities.
With the advent of advanced laser systems producing high-frequency x-ray beams, e.g. the EuropeanXFEL as a prominent example, a regime of laser-plasma interaction is reached, where all-optical methods are increasingly questionable (see Fig. 1). Instead, the interaction of hot electrons and the X-ray laser pulse must be modeled with a QED-driven approach. Future experiments taking place at HED-HIBEF, LCLS, and other facilities targeting this regime, will encounter processes in x-ray scattering from (laser-driven) relativistic electrons, where the effects of the energy spectrum of the laser field as well as multi-photon interactions can not be neglected anymore.
In contrast to the application window of existing QED-PIC codes, our event generator makes use of the fact that the classical nonlinearity parameter barely approaches unity in high-frequency regimes. Therefore, based on a momentum-space Furry-picture formulation of strong-field QED, this allows taking the finite bandwidth of the x-ray laser into account in the description of the QED-like multi-photon interaction.

Keywords: Strong-field QED; Monte-Carlo Event-Generation; Julia programming language

  • Open Access Logo Lecture (Conference)
    JuliaHEP 2023 Workshop, 06.-09.11.2023, Erlangen, Germany

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Permalink: https://www.hzdr.de/publications/Publ-37973
Publ.-Id: 37973


Molecular imaging of bacterial outer membrane vesicles based on bacterial surface display

Szöllősi, D.; Hajdrik, P.; Tordai, H.; Horváth, I.; Veres, D. S.; Gillich, B.; Das Shailaja, K.; Smeller, L.; Bergmann, R.; Bachmann, M.; Mihály, J.; Gaál, A.; Jezsó, B.; Barátki, B.; Kövesdi, D.; Bősze, S.; Szabó, I.; Felföldi, T.; Oszwald, E.; Padmanabhan, P.; Zoltán Gulyás, B.; Hamdani, N.; Máthé, D.; Varga, Z.; Szigeti, K.

The important roles of bacterial outer membrane vesicles (OMVs) in various diseases and their emergence as a promising platform for vaccine development and targeted drug delivery necessitates the development of imaging techniques suitable for quantifying their biodistribution with high precision. To address this requirement, we aimed to develop an OMV specific radiolabeling technique for positron emission tomography (PET). A novel bacterial strain (E. coli BL21(DE3) ΔnlpI, ΔlpxM) was created for efficient OMV production, and OMVs were characterized using various methods. SpyCatcher was anchored to the OMV outer membrane using autotransporter-based surface display systems. Synthetic SpyTag-NODAGA conjugates were tested for OMV surface binding and 64Cu labeling efficiency. The final labeling protocol shows a radiochemical purity of 100% with a ~ 29% radiolabeling efficiency and excellent serum stability. The in vivo biodistribution of OMVs labeled with 64Cu was determined in mice using PET/MRI imaging which revealed that the biodistribution of radiolabeled OMVs in mice is characteristic of previously reported data with the highest organ uptakes corresponding to the liver and spleen 3, 6, and 12 h following intravenous administration. This novel method can serve as a basis for a general OMV radiolabeling scheme and could be used in vaccine- and drug-carrier development based on bioengineered OMVs.

Permalink: https://www.hzdr.de/publications/Publ-37972
Publ.-Id: 37972


AND-Targeting of EpCAM+ and CEA+ colorectal cells using the modular Dual-RevCAR platform

González Soto, K. E.; Rodrigues Loureiro, L. R.; Abken, H.; Momburg, F.; Bachmann, M.; Feldmann, A.

Genetically engineered T cells expressing chimeric antigen receptors (CARs) have shown promising results particularly when targeting tumor associated antigens (TAAs) related to hematological malignancies. However, TAAs are usually expressed to some extend also on healthy tissues leading to on-target/off-tumor effects. To overcome this important safety issue along with improving targeting specificity and efficient killing of tumor escape variants, we adapted our Reverse CAR (RevCAR) system to follow an AND-gate Boolean logic. For that, Dual-RevCAR T cells were designed and armed with (I) a signaling (SIG) RevCAR, that includes the intracellular domain (ICD) of CD3 zeta; and (II) a costimulatory (COS) RevCAR, which contains a domain derived from CD28. Because the extracellular domains of both RevCARs are derived from the La/SS-B nuclear protein, Dual-RevCAR T cells will remain inactive until they encounter matching target modules (RevTMs). The bispecific antibody (bsAb)-like structure of the RevTMs allows their binding to RevCAR molecules and to specific antigens. However, only the simultaneous binding of RevTMs to SIG and COS RevCARs will promote the full activation of the Dual-RevCAR T cells. The epithelial cell adhesion molecule (EpCAM) and the carcinoembryonic antigen (CEA) have become appealing markers due to their overexpression in various solid tumor entities such as colorectal cancer, therefore representing promising target antigens for cancer immunotherapies following such a Dual Targeting CAR approach.

Having this in mind, the aim of this work was to assess the potential therapeutic application of the Dual-RevCAR system to target EpCAM and CEA following an AND-gating approach.

  • Poster
    TUMOR IMMUNOLOGY MEETS ONCOLOGY (TIMO) XVII 2023, 20.-22.04.2023, Halle, Germany

Permalink: https://www.hzdr.de/publications/Publ-37971
Publ.-Id: 37971


Pulsed Electromagnetic Field Effects on Dendritic Solidification in a Thin Cell

Shevchenko, N.; Bai, Q.; Kao, A.; Eckert, S.

This study aims to investigate how pulsed electromagnetic fields (PEMF) can affect grain refinement and microstructure during the solidification of a model Ga-In alloy. The magnetic system used generates field intensities of 8 - 11 mT and frequencies in the domain between 10 and 300 Hz, a duty cycle of 50%. We record the dendritic structures at the end of solidification experiments after switching OFF the electromagnetic field via X-ray radiographic imaging. Preliminary lab-scale results show that the solidification under frequencies above 100 Hz leads to dendrite fragmentation and solute redistribution in the mushy zone. No evidence of a CET is observed despite numerous fragmentation events. The fragments that detached from the dendritic network were unable to grow as equiaxed dendrites in the liquid as they became trapped within the dendritic network.

Keywords: Solidification; X-ray radiography; Dendrite fragmentation; Ga - In alloys; Pulsed electromagnetic fields

  • Lecture (Conference)
    International scientific colloquium “Modelling for Materials Processing”, 18.-19.09.2023, Riga, Latvia
  • Contribution to proceedings
    International Scientific Colloquium "Modelling for Materials Processing", 18.-19.09.2023, Riga, Latvia
    Proceedings of the IX International Scientific Colloquium "Modelling for Materials Processing", 70-75

Permalink: https://www.hzdr.de/publications/Publ-37970
Publ.-Id: 37970


Visualisation of flow effects in liquid and solidified metals

Shevchenko, N.; Lappan, T.; Eckert, S.

X-ray radiographic imaging is an efficient tool for investigating flow phenomena and solidification processes in optically opaque metallic alloys. This contribution is an overview of the latest advances in in-situ radiographic experiments made by the authors, as well as recent applications, including magnetohydrodynamic systems. We investigated a range of phenomena, such as bubble flow in liquid metal under an applied magnetic field, collective bubble dynamics, particle flow in liquid metal channels, and mesoscale solidification of alloys. Radiography measurements in liquid/solidified metal experiments are inevitably performed under adverse conditions of low signal-to-noise ratio, low image contrast, scattering, etc. To extract meaningful information from experimental data we combine both well-known methodology of data processing and our original codes. Examples of image analysis and results of in-situ experiments performed with low melting point alloys are presented and discussed in this contribution. A focus of these experiments is exploring scaled-down representative systems of industrial processes in metallic alloys.

Keywords: X-ray radiographic imaging; flow phenomena; solidification; Ga-In alloys

  • Lecture (Conference)
    Helmholtz Imaging Conference 2023, 14.-16.06.2023, Hamburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-37969
Publ.-Id: 37969


Understanding electronic correlations in warm dense quantum plasmas

Dornheim, T.

Warm dense matter (WDM)—an extreme state that is characterized by extreme densities and temperatures—
has emerged as one of the most active frontiers in plasma physics and material science. In nature,
WDM occurs in astrophysical objects such as giant planet interiors and brown dwarfs. In addition,
WDM is highly important for cutting-edge technological applications such as inertial confinement
fusion and the discovery of novel materials. In the laboratory, WDM is studied experimentally in
large facilities around the globe, and new techniques have facilitated unprecedented insights. Yet,
the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical
modeling, which is a notoriously difficult task [1].

In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo
(PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get new
insights into the behavior of WDM. Moreover, I will show how switching to the imaginary- time
representation allows us to significantly improve the interpretation of X-ray Thomson scattering
(XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will present a model-
free temperature diagnostic [4] based on the well-known principle of detailed balance, but available
for all wave numbers, and a new idea to directly extract the electron—electron static structure factor
from an XRTS measurement [5]. As an outlook, I will show how new PIMC capabilities will allow
to give us novel insights into electronic correlations in warm dense quantum plasmas, leading to
unprecedented agreement between experiments [6] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] S. Glenzer and R. Redmer, Reviews of Modern Physics 81, 1625 (2009)
[4] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[5] T. Dornheim et al., arXiv:2305.15305 (submitted)
[6] T. Döppner et al., Nature 618, 270-275 (2023)

  • Invited lecture (Conferences)
    Polish-German WE-Heraeus Seminar & Max Born Symposium, 04.-06.12.2023, Görlitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37967
Publ.-Id: 37967


Molybdenum Chloride Nanostructures with Giant Lattice Distortions Intercalated into Bilayer Graphene

Liu, Q.; Lin, Y.-C.; Kretschmer, S.; Ghorbani Asl, M.; Solís-Fernández, P.; Siao, M.-D.; Chiu, P.-W.; Ago, H.; Krasheninnikov, A.; Suenaga, K.

The nanospace of the van der Waals (vdW) gap between structural units of two-dimensional (2D) materials serves as a platform for growing unusual 2D systems through
intercalation and studying their properties. Various kinds ofmetal chlorides have previously been intercalated for tuning the properties of host layered materials, but the atomic structure of
the intercalants remains still unidentified. In this study, we investigate the atomic structural transformation of molybdenum(V) chloride (MoCl 5 ) after intercalation into
bilayer graphene (BLG). Using scanning transmission electron microscopy, we found that the intercalated material represents MoCl 3 networks, MoCl 2 chains, and Mo 5 Cl 10 rings. Giant lattice distortions and frequent structural transitions occur in the 2D MoCl x that have never been observed in metal chloride systems. The trend of symmetric to nonsymmetric structural
transformations can cause additional charge transfer from BLG to the intercalated MoCl x , as suggested by our density functional theory calculations. Our study deepens the understanding of the behavior of matter in the confined space of the vdW gap in BLG and provides hints at a more efficient tuning of material properties by intercalation for potential applications,
including transparent conductive films, optoelectronics, and energy storage.

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  • Secondary publication expected from 26.11.2024

Permalink: https://www.hzdr.de/publications/Publ-37966
Publ.-Id: 37966


The role of multiplicative noise in critical dynamics

de Oliveira Silvano, N.; Barci, D. G.

We study the role of multiplicative stochastic processes in the description of the dynamics of an order parameter near a critical point. We study equilibrium as well as out-of-equilibrium properties. By means of a functional formalism, we build the Dynamical Renormalization Group equations for a real scalar order parameter with symmetry, driven by a class of multiplicative stochastic processes with the same symmetry. We compute the flux diagram using a controlled -expansion, up to order. We find that, for dimensions the additive dynamic fixed point is unstable. The flux runs to a multiplicative fixed point driven by a diffusion function, where s the order parameter and is the fixed point value of the multiplicative noise coupling constant. We show that, even though the position of the fixed point depends on the stochastic prescription, the critical exponents do not. Therefore, different dynamics driven by different stochastic prescriptions (such as Itô, Stratonovich, anti-Itô and so on) are in the same universality class.

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Permalink: https://www.hzdr.de/publications/Publ-37965
Publ.-Id: 37965


Flexible, printable and eco-sustainable magnetoelectronics

Makarov, D.

Composites consisting of magnetic fillers in polymers and elastomers enable new application scenarios in soft robotics [1,2] and reconfigurable actuation [3]. Furthermore, they gave birth to the novel technology of solution processable magnetic field sensors. We demonstrate that printed magnetoelectronics can be stretchable, skin-conformal, capable of detection of low magnetic fields and withstand extreme mechanical deformations [4,5]. We feature the potential of our skin-conformal sensors in augmented reality settings for remote and touchless control of virtual objects, scrolling electronic documents and zooming maps. We put forth technology to realise magnetic field sensors, which can be printed and self-heal upon mechanical damage [6]. This opens exciting perspectives for magnetoelectronics in smart wearables, interactive printed electronics. Moreover, this research motivates further explorations towards the realization of eco-sustainable magnetoelectronics. For the latter, we will discuss biocompatible and biodegradable magneto sensitive devices, which can help to minimise electronic waste and bring magnetoelectronics to new application fields in medical implants and health monitoring.

[1] Y. Liu et al., Responsive magnetic nanocomposites for intelligent shape-morphing microrobots. ACS Nano 17, 8899 (2023).
[2] M. Richter et al., Locally addressable energy efficient actuation of magnetic soft actuator array systems. Advanced Science 2302077 (2023).
[3] M. Ha et al., Reconfigurable magnetic origami actuators with on-board sensing for guided assembly. Advanced Materials 33, 2008751 (2021).
[4] M. Ha et al., Printable and stretchable giant magnetoresistive sensors for highly compliant and skin-conformal electronics. Advanced Materials 33, 2005521 (2021).
[5] E. S. Oliveros Mata et al., Dispenser printed bismuth-based magnetic field sensors with non-saturating large magnetoresistance for touchless interactive surfaces. Adv. Mater. Technol. 7, 2200227 (2022).
[6] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: flexible magnetic field sensors; shapeable magnetoelectronics; printed magnetoelectronics; soft magnetic composites; Stimuli-responsive materials

Related publications

  • Invited lecture (Conferences)
    The 34th GCCCD Annual Conference “Chemistry and Chemical Engineering, Sensing the World”, 02.-03.12.2023, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-37964
Publ.-Id: 37964


Electron holographic mapping of structural reconstruction at mono- and bilayer steps of h-BN

Subakti, S.; Daqiqshirazi, M.; Wolf, D.; Linck, M.; Kern, F. L.; Jain, M.; Kretschmer, S.; Krasheninnikov, A.; Brumme, T.; Lubk, A.

Here, by making use of medium and high resolution autocorrected off-axis electron holography, we directly probe the electrostatic potential as well as in-plane structural reconstruction at edges and steps in multilayer hexagonal boron nitride. In combination with ab initio calculations, the data allows revealing the formation of folded zigzag edges at steps comprising two monolayers and their absence at monolayer steps.

Permalink: https://www.hzdr.de/publications/Publ-37962
Publ.-Id: 37962


Measurement and Simulation of Ultra-Low-Energy Ion–Solid Interaction Dynamics

Titze, M.; Poplawsky, J. D.; Kretschmer, S.; Krasheninnikov, A.; Doyle, B. L.; Bielejec, E. S.; Hobler, G.; Belianinov, A.

Ion implantation is a key capability for the semiconductor industry. As devices shrink, novel materials enter the manufacturing line, and quantum technologies transition to being more mainstream. Traditional implantation methods fall short in terms of energy, ion species, and positional precision. Here, we demonstrate 1 keV focused ion beam Au implantation into Si and validate the results via atom probe tomography. We show the Au implant depth at 1 keV is 0.8 nm and that identical results for low-energy ion implants can be achieved by either lowering the column voltage or decelerating ions using bias while maintaining a sub-micron beam focus. We compare
our experimental results to static calculations using SRIM and dynamic calculations using binary collision approximation codes TRIDYN and IMSIL. A large discrepancy between the static and dynamic simulation is found, which is due to lattice enrichment with high-stopping-power Au and surface sputtering. Additionally, we demonstrate how model details are particularly important to the simulation of these low-energy heavy-ion implantations. Finally, we discuss how our results pave a way towards much lower implantation energies while maintaining high spatial resolution.

Keywords: focused ion beam; ion implantation; ultra-low energy

Permalink: https://www.hzdr.de/publications/Publ-37961
Publ.-Id: 37961


Learning from nature: recovery of rare earth elements by the extremophilic bacterium Methylacidiphilum fumariolicum

Singer, H.; Steudtner, R.; Sottorff, I.; Drobot, B.; Pol, A.; Op Den Camp, H. J. M.; Daumann, L. J.

We present the extremophilic bacterium Methylacidiphilum fumariolicum SolV as a platform for the recovery of rare earth elements (REE). Strain SolV is able to selectively extract the light REE from artificial industrial waste sources, natural REE-containing and postmining waters. Upscaling, different media composition and accumulation over several cycles were successfully implemented, underlining the potential for bio-recovery of REE.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37960
Publ.-Id: 37960


58 DERA Rohstoffinformationen Abschlussbericht Dialogplattform Recyclingrohstoffe

Raatz, S.; Deutsche Rohstoffagentur; Deutsche Akademie der Technikwissenschaften; (Editors)

Der Industriestandort Deutschland ist auf eine sichere und nachhaltige Versorgung mit mineralischen Rohstoffen angewiesen. Hierbei wird das Recycling von Rohstoffen als weiteres Standbein der Versorgung neben der heimischen Rohstoffgewinnung und dem Import von Rohstoffen künftig eine immer wichtigere Rolle spielen. In diesem Zusammenhang veröffentlichte das Bundesministerium für Wirtschaft und Klimaschutz (BMWK) im Januar 2023 das Eckpunktepapier „Wege zu einer nachhaltigen und resilienten Rohstoffversorgung“ und unterstrich darin die strategische Bedeutung einer engen Verzahnung von Kreislaufwirtschafts- und Rohstoffstrategie.
Die Dialogplattform Recyclingrohstoffe wurde im Rahmen der Deutschen Rohstoffstrategie 2020 mit dem Ziel beauftragt, Maßnahmen zu erarbeiten, die den Beitrag von Recyclingrohstoffen (Sekundärrohstoffen) für die Versorgungssicherheit von Metallen und Industriemineralen stärken.
Hierzu wurden in einem Dialogprozess mit über 380 Vertreterinnen und Vertretern aus Wirtschaft, Wissenschaft und Verwaltung sowie Zivilgesellschaft über einen Zeitraum von zwei Jahren in zwei Arbeitskreisen (Metalle und Industrieminerale) mit insgesamt acht Unterarbeitskreisen konkrete Handlungsoptionen entwickelt. Der inhaltliche Zuschnitt der Unterarbeitskreise orientierte sich an spezifischen Stoffströmen, die zum Beispiel aufgrund ihrer Mengenrelevanz, Kritikalität oder ihres Beitrags zu Treibhausgasemissionen von besonderer Relevanz sind und stoffstromspezifische Anforderungen an das Recycling stellen. Darüber hinaus spielte die in den Unterarbeitskreisen vorhandene Expertise der Teilnehmenden eine Rolle beim finalen Zuschnitt der Themen.
Die Ergebnisse aus den Unterarbeitskreisen bilden den inhaltlichen Kern des vollzogenen Dialogprozesses und werden in Steckbriefen beschrieben. So liegen für den Arbeitskreis Metalle detaillierte Steckbriefe für die Stoffströme Aluminium, Eisen und Stahl, Kupfer sowie Technologiemetalle vor.
Der Arbeitskreis Industrieminerale umfasst detaillierte Steckbriefe für die Stoffströme Baurohstoffe, Gips, Keramische Rohstoffe (Feuerfestkeramik) sowie Industrielle Reststoffe und Nebenprodukte.
Insgesamt wurden über die gesamte Projektlaufzeit 94 stoffstromspezifische Handlungsoptionen in den verschiedenen Unterarbeitskreisen erarbeitet, die auf einer systematischen Analyse bestehender Barrieren basieren. Alle Handlungsoptionen für die spezifischen Stoffströme finden sich im jeweiligen Steckbrief. Auf Ebene der beiden Arbeitskreise Metalle und Industrieminerale wurden zudem neun stoffstromübergreifende Handlungsfelder aggregiert, zu denen unter den Teilnehmenden Einigkeit erzielt werden konnte. Weitere Themenbereiche, die einem verbesserten Recycling potenziell zuträglich sind, zu denen jedoch kontroverse Diskussionen unter den Teilnehmenden stattfanden, werden in diesem Bericht transparent dargelegt. Ferner ist zu beachten, dass alle übergreifenden Handlungsfelder einen direkten Recyclingbezug aufweisen. Weiter gefasste wirtschaftspolitische Instrumente, zum Beispiel aus dem Bereich der Klimapolitik, die ebenfalls einen förderlichen Effekt auf ein verstärktes Recycling haben können, wie eine CO2-Bepreisung oder ein Emissionshandel, sind daher nicht vertiefend in der Dialogarbeit aufgegriffen worden. Nachfolgend sind die übergreifenden Handlungsfelder der beiden Arbeitskreise kurz zusammengefasst, wobei die Relevanz der genannten Themen zwischen den Unterarbeitskreisen zum Teil erheblich variiert.
Die ausführlichen Steckbriefe der acht stoffstromspezifischen Unterarbeitskreise, die in dieser Kurzfassung nur umrissen werden, umfassen weitere Handlungsoptionen und betten diese jeweils in die Ausgangslage des Status quo und die daraus resultierenden Barrieren für das Recycling ein. Des Weiteren umfassen die separat zur Verfügung gestellten Steckbriefe eine differenzierte Beurteilung der „Machbarkeit“ sowie möglicher Zielkonflikte in der Umsetzung der jeweiligen Handlungsoptionen. Gerade diese einbettende Betrachtung der vorgeschlagenen Handlungsoptionen stellt einen zentralen Mehrwert der Dialogarbeit dar, da den Lesenden hierdurch ein umfassenderes Verständnis der Vor- und gegebenenfalls auch Nachteile ermöglicht werden soll.

Keywords: Rohstoffe; Recylcing; Versorgungssicherheit; Industrie; Arbeitskreis Metalle; Metalle

Permalink: https://www.hzdr.de/publications/Publ-37959
Publ.-Id: 37959


Terahertz Néel spin-orbit torques drive nonlinear magnon dynamics in antiferromagnetic Mn2Au

Behovits, Y.; Chekhov, A. L.; Bodnar, S. Y.; Gueckstock, O.; Reimers, S.; Lytvynenko, Y.; Skourski, Y.; Wolf, M.; Seifert, T. S.; Gomonay, O.; Kläui, M.; Jourdan, M.; Kampfrath, T.

Antiferromagnets have large potential for ultrafast coherent switching of magnetic order with minimum heat dissipation. In materials such as Mn2Au and CuMnAs, electric rather than magnetic fields may control antiferromagnetic order by Néel spin-orbit torques (NSOTs). However, these torques have not yet been observed on ultrafast time scales. Here, we excite Mn2Au thin films with phase-locked single-cycle terahertz electromagnetic pulses and monitor the spin response with femtosecond magneto-optic probes.We observe signals whose symmetry, dynamics, terahertz-field scaling and dependence on sample structure are fully consistent with a uniform inplane antiferromagnetic magnon driven by field-like terahertz NSOTs with a torkance of (150 ± 50) cm2 A−1 s−1. At incident terahertz electric fields above 500 kV cm−1, we find pronounced nonlinear dynamics with massive Néelvector deflections by asmuch as 30°. Our data are in excellent agreement with a micromagnetic model. It indicates that fully coherent Néel-vector switching by 90° within 1 ps is within close reach.

Permalink: https://www.hzdr.de/publications/Publ-37957
Publ.-Id: 37957


Data publication: Minor Actinides Can Replace Essential Lanthanides in Bacterial Life

Singer, H.; Steudtner, R.; Klein, A. S.; Rulofs, C.; Zeymer, C.; Drobot, B.; Pol, A.; Martinez-Gomez, C.; Daumann, L. J.

Rohdaten aus denen Ergebnisse und Grafiken erstellt wurden um die benötigten Erkenntnisse für diese Publikation zu generieren

Keywords: Actinides; Lanthanides; Lanthanide-dependent bacteria; Methanol dehydrogenases; Lanthanide-binding proteins; Methane

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Permalink: https://www.hzdr.de/publications/Publ-37956
Publ.-Id: 37956


Physics-enhanced neural networks for equation-of-state calculations

Callow, T. J.; Nikl, J.; Kraisler, E.; Cangi, A.

Fast and accurate equation-of-state (EOS) data is of critical importance in the warm dense matter (WDM) regime, for example as input to hydrodynamic codes used in inertial confinement fusion modelling. Since EOS data must be generated on-the-fly for many applications, a tabular approach based on interpolation of known data points is generally used. Alternatively, average-atom models are (in some cases) fast enough to generate on-the-fly EOS data in an ab initio way, i.e. without empirical inputs. In this presentation, we present a newly-developed method which can be considered a hybrid of these two approaches. In our method, we use data generated by average-atom models as input features to a neural network model [1], which is trained on the first principles EOS dataset of Militzer and co-workers [2]. This approach has several advantages relative to using an unmodified average-atom model, and relative to standard interpolation techniques.

[1] Callow, T. J., Kraisler, E., & Cangi, A. (2023). Physics-enhanced neural networks for equation-of-state calculations. arXiv preprint arXiv:2305.06856.
[2] Militzer, B., González-Cataldo, F., Zhang, S., Driver, K. P., & Soubiran, F. (2021). First-principles equation of state database for warm dense matter computation. Phys. Rev. E, 103(1), 013203

Keywords: Warm-dense matter; Average-atom models

  • Open Access Logo Lecture (Conference)
    Polish-German WE-Heraeus Seminar & Max Born Symposium, 04.-06.12.2023, Görlitz, Deutschland
  • Open Access Logo Machine Learning: Science and Technology 4(2023), 045055
    DOI: 10.1088/2632-2153/ad13b9

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Permalink: https://www.hzdr.de/publications/Publ-37955
Publ.-Id: 37955


Wire-mesh sensor data for vertical upward gas-liquid flow

Kipping, R.; Schleicher, E.

This data set contains the processed data of the wire-mesh sensor, obtained in a flow loop with inner diameter of 50 mm with a vertical section of 3 m length. The dimension of the sensor is 16x16 wires and a lateral wire distance of 3.125 mm. Each file contains data of 60 s measurement time with 10 kHz samling frequency.

The set up was operated with pressurized air and deionized water. The experimental matrix contains meausrements at different superficial velocities of the gas and the liquid. Thus different flow pattern are observed. For injection of the gas two different types have been used. In the first set of experiments (files 1- 61, *injection1*) the gas was injected with a small tube with inner diameter of 9 mm. In the second set of experiments (files 101 - 151, *injection2*) the gas was injected with a small pipe of 25 mm inner diameter.

An overview of the experimental conditions for the two sets of experiments are summarized in the excel file. The corresponding *.zip files contain the processed data. These are void files, which contain the gas holdup in each crossing point and for all time steps of the measurement stack. Additionally the time averaged cross sectional gas holdup distribution (*.epsxy), the time averaged radial gas holdup (*.epsrad_20) and the cross sectional average gas holdup at each time step (*.epst) is provided,

Keywords: two-phase flow; wire-mesh sensor

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Permalink: https://www.hzdr.de/publications/Publ-37954
Publ.-Id: 37954


Introducing Relative Encounter Rates: a scale-invariant home range measure of animal interaction

Saraiva De Menezes, J. F.; Fleming, C. H.; Martinez Garcia, R.; Belant, J. L.; Medici, E. P.; Morato, R. G.; Calabrese, J.

Animal encounters are key components of population dynamics, community dynamics, and
evolutionary processes. Consequently, measuring encounter rates (i.e. encounters per time) can be
insightful. Encounter rates can be measured from animal tracking data, using metrics that can be split
into two groups. The first group consists of trajectory-based metrics, i.e. measures based on serial
records of animal locations. This first group includes PROX, the number of observed per number of
samples. The second group, in contrast, consists of metrics based on home range overlap, including
the Bhattacharyya coefficient (BC). In this study, we argue both types of metrics are limited.
Trajectory-based metrics are direct measures of encounter rates but have statistical estimation
issues due to their dependency on the frequency of location sampling. Meanwhile, home-rangebased metrics are statistically sound but are not proportional to encounter rates. To overcome both
challenges, we proposed a new metric, Relative Encounter Rate (RER). RER increases linearly with the
number of encounters and does not depend on the frequency of sampling (i.e. it is scale-invariant). In
an individual-based simulation, we measured how RER, BC, and PROX relative error under different
sample sizes and sampling frequencies. Further, we compared these metrics in three empirical case
studies. We tested Jaguars for polygyny, deforestation effects on tapir connectivity, and an extension
of the dearest enemy hypothesis with brown bears. We also compared partner hierarchy according
to BC and RER in Jaguar mating clusters. In the simulation study, we found PROX overestimates the
encounter rate when data has a low sampling frequency. The simulation also indicates BC
overestimated encounters. Furthermore, PROX led to false positives in the Tapir and Bear case
studies. In addition, PROX was incapable of detecting many individual relationships in the jaguar
polygyny study. RER does not depend on sampling frequency (contrary to PROX) or sample size
(contrary to BC). We discuss further hypotheses to test with RER and argue RER can enable ecologists
to analyze encounters with a level of detail adequate to their importance, leading to a better
understanding of how individual behaviors influence population and community dynamics.

  • Open Access Logo Poster
    GRC Movement Ecology Conference, 28.05.-02.06.2023, Renaissance Tuscany Il Ciocco, Italy

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Permalink: https://www.hzdr.de/publications/Publ-37953
Publ.-Id: 37953


Knowledge and technology transfer in and beyond mineral exploration

Kesselring, M.; Kirsch, M.; Wagner, F.; Gloaguen, R.

In natural sciences, mineral exploration has a high network centrality. For industries with high technological- and knowledge proximity, transfer effects are an important function for innovation. Despite the high level of proximity between mineral exploration and other natural sciences, scholars hardly examine transfers from and to mineral exploration. This paper analyzes obstacles and mechanisms of transfer effects in and from mineral exploration and finds answers on how to institutionalize knowledge and technology transfer (KTT). The study employs a qualitative research design. The underlying database consists of 16 expert interviews, from the fields of natural science. The results show that KTT between areas as diverse as mineral exploration, healthcare, and arts are possible. A lack of interdisciplinary exchange and rigid scientific structures is the main inhibitor of KTT. Before this study, evidence for KTT from and to smaller industries is mostly anecdotal. The study is among the few, which investigates KTT concerning functional transfer opportunities.

Keywords: Knowledge transfer; Technology transfer; Mineral exploration; Natural sciences

Permalink: https://www.hzdr.de/publications/Publ-37952
Publ.-Id: 37952


Effect of carbon content on electronic structure of uranium carbides

Butorin, S. M.; Bauters, S.; Amidani, L.; Beck, A.; Rossberg, A.; Weiss, S.; Vitova, T.; Kvashnina, K.; Tougait, O.

The electronic structure of UC (x = 0.9, 1.0, 1.1, 2.0) was studied by means of x-ray absorption spectroscopy (XAS) at the C K edge and measurements in the high energy resolution fluorescence detection (HERFD) mode at the U and edges. The full-relativistic density functional theory calculations taking into account the Coulomb interaction U and spin-orbit coupling (DFT+U+SOC) were also performed for UC and UC. While the U HERFD-XAS spectra of the studied samples reveal little difference, the U HERFD-XAS spectra show certain sensitivity to the varying carbon content in uranium carbides. The observed gradual changes in the U HERFD spectra suggest an increase in the C 2p-U 5f charge transfer, which is supported by the orbital population analysis in the DFT+U+SOC calculations, indicating an increase in the U 5f occupancy in UC as compared to that in UC. On the other hand, the density of states at the Fermi level were found to be significantly lower in UC, thus affecting the thermodynamic properties. Both the x-ray spectroscopic data (in particular, the C K XAS measurements) and results of the DFT+U+SOC calculations indicate the importance of taking into account U and SOC for the description of the electronic structure of actinide carbides.

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Permalink: https://www.hzdr.de/publications/Publ-37950
Publ.-Id: 37950


Influence of the cement additive PBTC on aquatic uranium(VI) speciation and retention on cementitious material

Wollenberg, A.; Acker, M.; Kretzschmar, J.; Schmeide, K.; Tsushima, S.; Chiorescu, I.; Krüger, S.

The ingress of water into an underground nuclear repository, described as a worst-case scenario, can lead to the degradation of cement-based engineered barriers and thus to the release of organic cement additives that can affect radionuclide immobilisation. The additive 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) is one of the most commonly used long-term retarders in cement, and also used as a corrosion inhibitor in reinforced concrete and steel. PBTC
is an organophosphonate ligand with one phosphonate and three carboxyl groups [1]. These functional groups make PBTC an effective dispersant and strong complexing agent for various metal ions (e.g. Ca2+, Al3+, Fe3+). However, neither the complexation of radionuclides by PBTC nor the influence of PBTC on radionuclide retention in cement phases has been investigated.
Therefore, both the complexation of U(VI) with PBTC in solution (binary system) and the influence of PBTC on the U(VI) retention by cementitious materials (ternary system) were investigated for the first time. The U(VI) complexation studies were performed by different series varying the pH from 2 to 11 and/or the U(VI) to PBTC ratio. The structure-sensitive methods NMR, IR and Raman spectroscopy were used to characterize the complex structure. Complementary DFT calculations were carried out. The U(VI) speciation in presence of PBTC was determined by UV-Vis and TRLFS spectroscopy. In the case of PBTC excess, soluble complex species are formed up to pH >10, which is relevant for cementitious systems due to degradation processes. For the U(VI) retention studies both calcium (aluminate) silicate hydrate (C-(A-)S-H) phases of different compositions, representing different cement degradation stages, as well as hardened cement paste were applied. TRLFS was applied to characterize the U(VI) binding. The PBTC retention was quantified by 1H and 31P solution NMR.

Keywords: uranium; 2-phosphonobutane-1,2,4-tricarboxylic acid; complexation; stability constants; cement; retention; spectroscopy

  • Lecture (Conference)
    Joint 6th International Workshop on Mechanisms and Modelling of Waste / Cement Interactions, 20.-22.11.2023, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-37949
Publ.-Id: 37949


Structural identification of aquatic U(VI)-PBTC complexes by spectroscopic investigations

Wollenberg, A.; Kretzschmar, J.; Tsushima, S.; Krüger, S.; Acker, M.; Taut, S.; Stumpf, T.

In a nuclear waste repository, cement-based materials are to be used for waste conditioning and as an engineered barrier. The ingress of water into the nuclear waste repository, described as a worst-case scenario, leads to increased aging and degradation of the concrete. These processes are associated with a leaching of diverse organic substances usually added to the cement to realize the desired physicochemical and mechanical properties of the cement-based materials. The impact of the additives is based on their excellent ability to complex metal ions. Consequently, the complexation behavior of such additives towards radionuclides (RN) and thus their impact on RN mobilization and migration into the environment is essential for a comprehensive risk assessment. One of the additives commonly used for long-term retardation of cement hardening is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).
PBTC is a polyfunctional ligand possessing three carboxyl groups and one phosphonate group, which have been shown to make PBTC a strong complexing agent for various metal ions (e.g. Ca2+, Zn2+, Al3+, Fe3+) [1,2]. However, to date, there are no studies on PBTC interaction with radionuclides. Therefore,
the complexation of PBTC with U(VI) was investigated for the first time, using different spectroscopic methods over a wide pH range (2 through 11) to identify and characterize possible complex species.
U(VI)-PBTC species with solubility as high as 100 mM were observed throughout the entire pH range studied, especially when PBTC is in excess. This allowed the convenient application of structuresensitive methods such as NMR, IR, and Raman spectroscopies. Furthermore, time-resolved laserinduced
fluorescence spectroscopy (TRLFS) and UV-Vis titration studies provided insight into U(VI)–PBTC system’s speciation.

Keywords: uranium(VI); 2-phosphonobutane-1,2,4-tricarboxylic acid; complexation; stability constants; spectroscopy

  • Lecture (Conference)
    18th International Conference on the Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere - Migration 2023, 24.-29.09.2023, Nantes, France

Permalink: https://www.hzdr.de/publications/Publ-37948
Publ.-Id: 37948


Characterisation of highly soluble U(VI)-PBTC complexes

Wollenberg, A.; Kretzschmar, J.; Schmeide, K.; Acker, M.; Taut, S.; Stumpf, T.

Organophosphonates are used multipurpose in the chemical industry. One of the most commonly used organophosphonates is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).[1] The functional groups of PBTC consist of one phosphonate and three carboxylate groups, which make PBTC not only an effective dispersant, but also a very good complexing agent for various metal ions (e.g. Ca2+, Al3+, Fe3+).[2,3] Due to these properties, PBTC is used, for example, as an efficient long-term retarder in cement, as a corrosion inhibitor in reinforced concrete and steel, or as a scale inhibitor in water treatment plants or cooling water circulation systems.[4,5] However, this ubiquitous use can also lead to anthropogenic discharge into the environment, where PBTC can complex heavy metals or even radionuclides. Complexation can increase the solubility of metal ions and thus their bioavailability. As a result, there is an increased risk of toxic metal ions being distributed in the environment and thus also being absorbed into the human food chain.
However, to date there have been no studies on the complexation of PBTC with radionuclides. For this reason, the complexation of PBTC with U(VI) in the pH range from 1 to 11 was investigated for the first time using various spectroscopic methods. The studies were performed by different series varying the pH or the U(VI) to PBTC ratio. For the methods used, U(VI) concentrations in the mM range were employed, which was possible due to the very good water solubility of the U(VI)-PBTC complexes. The structure-sensitive methods NMR, IR and Raman spectroscopy were used to characterise the complex structure. Supporting DFT calculations were carried out. The stability constants of the complex species were determined by UV-Vis spectroscopy. By applying the different spectroscopic methods, it was possible to determine chelation of U(VI) by the phosphonate group and one of the carboxyl groups. Furthermore, by means of factor analysis, the distribution of complex species as well as the complexation constants could be determined for the first time. Therefore, the results of this study make it possible to evaluate the risk of PBTC entering the environment in relation to the radionuclide uranium.

Keywords: uranium(VI); 2-phosphonobutane-1,2,4-tricarboxylic acid; complexation; stability constants; spectroscopy

  • Lecture (Conference)
    5th International Caparica Conference on Pollutant Toxic Ions and Molecules (PTIM) 2023, 06.-09.11.2023, Caparica, Portugal

Permalink: https://www.hzdr.de/publications/Publ-37947
Publ.-Id: 37947


Magnetic structure and phase diagram of the Heisenberg-Ising spin chain antiferromagnetic PbCo2V2O8

Puzniak, K.; Aguilar-Maldonado, C.; Feyerherm, R.; Prokes, K.; Islam, A. T. M. N.; Skourski, Y.; Keller, L.; Lake, B.

The effective spin-1/2 antiferromagnetic Heisenberg-Ising chain materials, ACo2V2O8, A = Sr, Ba, are a rich source of exotic fundamental phenomena and have been investigated for their model magnetic properties both in zero and nonzero magnetic fields. Here we investigate a new member of the family, namely, PbCo2V2O8. We synthesize powder and single-crystal samples of PbCo2V2O8 and determine its magnetic structure using neutron diffraction. Furthermore, the magnetic field/temperature phase diagrams for a magnetic field applied along the c, a, and [110] crystallographic directions in the tetragonal unit cell are determined via magnetization and heat capacity measurements. A complex series of phases and quantum phase transitions are discovered that strongly depend on both the magnitude and direction of the field. Our results show that PbCo2V2O is an effective spin-1/2 antiferromagnetic Heisenberg-Ising chain with properties that are, in general, comparable to those of SrCo2V2O8 and BaCo2V2O8. One interesting departure from the results of these related compounds is, however, the discovery of a new field-induced phase for the field direction H ӏӏ [110].

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Permalink: https://www.hzdr.de/publications/Publ-37943
Publ.-Id: 37943


300 mm CMOS-compatible superconducting HfN and ZrN thin films for quantum applications

Potjan, R.; Wislicenus, M.; Ostien, O.; Hoffmann, R.; Lederer, M.; Reck, A.; Emara, J.; Roy, L.; Lilienthal-Uhlig, B.; Wosnitza, J.

The rising interest in increased manufacturing maturity of quantum processing units is pushing the development of alternative superconducting materials for semiconductor fab process technology. However, these are often facing CMOS process incompatibility. In contrast to common CMOS materials, such as Al, TiN, and TaN, reports on the superconductivity of other suitable transition-metal nitrides are scarce, despite potential superiority. Here, we demonstrate fully CMOS-compatible fabrication of HfN and ZrN thin films on state-of-the-art 300mm semiconductor process equipment, utilizing reactive DC magnetron sputtering on silicon wafers. Measurement of mechanical stress and surface roughness of the thin films demonstrates process compatibility. We investigated the materials phase and stoichiometry by structural analysis. The HfN and ZrN samples exhibit superconducting phase transitions with critical temperatures up to 5.84 and 7.32 K, critical fields of 1.73 and 6.40 T, and coherence lengths of 14 and 7 nm, respectively. A decrease in the critical temperature with decreasing film thickness indicates mesoscopic behavior due to geometric and grain-size limitations. The results promise a scalable application of HfN and ZrN in quantum computing and related fields.

  • Open Access Logo Applied Physics Letters 123(2023), 172602
    Online First (2023) DOI: 10.1063/5.0176060

Permalink: https://www.hzdr.de/publications/Publ-37942
Publ.-Id: 37942


Local-symmetry-sensitive elastic softening in the Kramers doublet system Y1−xNdxCo2Zn20

Ishii, I.; Umeno, T.; Yamamoto, R.; Onimaru, T.; Suzuki, T.; Araki, K.; Miyata, A.; Zherlitsyn, S.; Wosnitza, J.

We investigated the elastic properties of Y1−xNdxCo2Zn20 with localized Nd f electrons and ground-state Kramers doublet. All longitudinal and transverse moduli of NdCo2Zn20 (x = 1) show an elastic softening below 50 K accompanied by a minimum around 2.5 K. The softening, which is robust to magnetic fields up to 8 T, is not observed for samples with Nd concentrations of x = 0.19, 0.05, and 0. In localized f electron systems, elastic softening from high temperatures is often understood by crystal electric field effects; however, this cannot explain the behavior in NdCo2Zn20. Our experimental and calculated results reveal that the softening neither is caused by a phonon contribution, a Nd3+ single-site effect, nor a magnetic interaction. We conclude that the softening is due to a local-symmetry-sensitive electronic state in NdCo2Zn20.

Permalink: https://www.hzdr.de/publications/Publ-37941
Publ.-Id: 37941


Giant irreversibility of the inverse magnetocaloric effect in the Ni47Mn40Sn12.5Cu0.5 Heusler alloy

Kamantsev, A. P.; Koshkidko, Y. S.; Bykov, E.; Gottschall, T.; Gamzatov, A. G.; Aliev, A. M.; Varzaneh, A. G.; Kameli, P.

Direct studies of the adiabatic temperature change (ΔTad) in the Ni47Mn40Sn12.5Cu0.5 Heusler alloy in steady magnetic fields up to 8 T by the extraction method and in pulsed magnetic fields up to 50 T were carried out in this paper. The alloy Ni47Mn40Sn12.5Cu0.5 demonstrates a magnetostructural phase transition (MSPT) of the first order in the 254–283 K temperature range as well as a second order phase transition near the Curie temperature TC = 313 K. An inverse magnetocaloric effect (MCE) was found in the region of the MSPT, and it reaches the maximum value ΔTad = -12 K in 20 T at the initial temperature T0 = 275 K. The irreversible part of the MCE reached ΔTir = -10 K when the field is completely removed. We consider the dynamics of the MCE in the vicinity of the MSPT and discuss the mechanisms that cause the giant irreversibility of the MCE as well as the possibilities of its application in hybrid cooling systems.

Permalink: https://www.hzdr.de/publications/Publ-37940
Publ.-Id: 37940


Characterization of domain wall patterns in granular antiferromagnetic Cr2O3 films

Pylypovskyi, O.; Hedrich, N.; Tomilo, A.; Kosub, T.; Wagner, K.; Hübner, R.; Shields, B.; Sheka, D.; Faßbender, J.; Maletinsky, P.; Makarov, D.

Cr2O3 is an exceptional antiferromagnet with an easy axis of anisotropy that exhibits a magnetoelectric effect at room temperature [1]. Although there are technological challenges to use it for applications because of the relatively low bulk Neel temperature of TN = 308 K, there are demonstrations that TN can be substantially enhanced by strain in thin films. The morphology and growth procedure of such samples allow the appearance of flexomagnetic effects and pinning of domain walls at grain boundaries [2,3].

Here, we propose a material model of granular antiferromagnetic films and apply it to maze-like domain patterns in thin Cr2O3 samples [4]. The domain pattern is obtained by means of the nitrogen vacancy magnetometry and compared with spin-lattice simulations. We analyze the statistics of the size and self-similarity of the domain wall patterns to correlate the experimental measurements with the parameters of the theoretical model and compare the domain wall patterns with predictions made by a machine learning approach. The estimated inter-grain coupling is characterized by a substantial reduction of the effective exchange coupling to about 10% of the bulk value, with a wide standard deviation. Based on the material model, we provide design rules for the granular AFM recording media.

Keywords: Cr2O3; granular antiferromagnet

  • Lecture (others)
    WEH Seminar, 02.-05.01.2024, Bad Honnef, Germany

Permalink: https://www.hzdr.de/publications/Publ-37939
Publ.-Id: 37939


Foundational Competencies and Responsibilities of a Research Software Engineer

Goth, F.; Alves, R.; Braun, M.; Jael Castro, L.; Chourdakis, G.; Christ, S.; Cohen, J.; Erxleben, F.; Grad, J.-N.; Hagdorn, M.; Hodges, T.; Juckeland, G.; Kempf, D.; Lamprecht, A.-L.; Linxweiler, J.; Schwarzmeier, M.; Seibold, H.; Philipp Thiele, J.; von Waldow, H.; Wittke, S.

The term Research Software Engineer, or RSE, emerged a little over 10 years ago as a way to represent
individuals working in the research community but focusing on software development. The term has been widely
adopted and there are a number of high-level definitions of what an RSE is. However, the roles of RSEs vary
depending on the institutional context they work in. At one end of the spectrum, RSE roles may look similar to
a traditional research role. At the other extreme, they resemble that of a software engineer in industry. Most
RSE roles inhabit the space between these two extremes. Therefore, providing a straightforward, comprehensive
definition of what an RSE does and what experience, skills and competencies are required to become one is
challenging. In this community paper we define the broad notion of what an RSE is, explore the different types
of work they undertake, and define a list of fundamental competencies as well as values that define the general
profile of an RSE. On this basis, we elaborate on the progression of these skills along different dimensions, looking
at specific types of RSE roles, proposing recommendations for organisations, and giving examples of future
specialisations. An appendix details how existing curricula fit into this framework.

Keywords: research software engineering; curriculum design; training; learning; competencies; certification

Permalink: https://www.hzdr.de/publications/Publ-37938
Publ.-Id: 37938


Helmholtz Metadata Collaboration - Facilitating FAIR metadata in Helmholtz

Schaller, T.; Günter, G.; Kubin, M.; Özkan, Ö.; Rau, F.; Steinmeier, L.

Data are an essential part of every scientific endeavour. An efficient and future oriented research data management is therefore essential in order to ensure long-term availability of the generated data. This in turn ensures the reproducibility of scientific results. In order to facilitate FAIR data management within the Helmholtz community the incubator platform “Helmholtz Metadata Collaboration (HMC)” was established.

HMC develops and provides services, tools and trainings to support and improve FAIR (meta)data management in the Helmholtz Association and aligns these approaches with national and international approaches and initiatives (e.g. RDA, EOSC, NFDI) to ensure compatibility with international research communities.

To achieve this goal, HMC builds its work along three strategic areas: (1) Assessing and monitoring the state of FAIR data across Helmholtz, (2) Facilitating the connectivity of Helmholtz research data, and (3) Transforming (meta)data recommendations into implementations. At the centres, HMC supports research communities and data professionals with six research-field specific hubs: At HZDR HMC is represented locally by a unit dedicated to research field Energy and remotely by a unit for research field Matter. In our poster we will illustrate how research and data professional communities at HZDR can benefit from HMC's services, tools and trainings.

Keywords: Helmholtz-Zentrum Dresden-Rossendorf; HZDR data management day; metadata management; Helmholtz Metadata Collaboration

  • Poster
    HZDR Data Management Day, 21.11.2023, Dresden, Dresden

Permalink: https://www.hzdr.de/publications/Publ-37937
Publ.-Id: 37937


Influence of selected organics on the retention of uranium(VI) by calcium-(aluminate-)silicate-hydrate phases

Schmeide, K.; Kretzschmar, J.; Huittinen, N. M.

Most underground nuclear waste disposal concepts envisage the extensive use of cementitious materials in the geo-engineered barrier as a buffer and borehole sealing material and to ensure the mechanical stability of disposal systems. In order to assess the radionuclide (RN) retention potential of these barrier materials, it is necessary to study the impact of various repository relevant conditions that will evolve over time, such as changed pH values, increased ionic strength, elevated temperatures, or the release of organic components. The U(VI) retention by calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, forming owing to Al-rich additives in cement formulations, was studied for samples with C/S molar ratios of 0.8, 1.2, and 1.6, representing different alteration stages of concrete, and with increasing A/S molar ratios of 0, 0.06, and 0.18 in each series, with special focus on the presence of organics. The latter thereby comprise gluconate (GLU), 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC), and a mixture of cellulose degradation products (CDP) obtained from dry radiolysis (dose rate 0.6 kGy/h, absorbed dose ~ 1.37 MGy) followed by hydrolysis in artificial cement water (pH > 13, anoxic conditions) provided by project partners within the CORI framework. Complementary analytical techniques were applied to address the different specific aspects of the cement / organics / RN ternary systems. 27Al and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (XRD) were applied to determine the bulk structure and composition of the synthesized C-(A-)S-H phases. 13C-, and in case of PBTC also 31P-, MAS NMR measurements aimed at localization and speciation of the organic components involved [1]. 1H and 31P solution NMR of the aqueous phase allowed for quantification of the organics’ fraction removed from solution and hence associated with the solid phase. Retained U(VI) species were identified by time-resolved laser-induced luminescence spectroscopy (TRLFS). Zeta-potential measurements were conducted to study the organics’ influence on the surface charge and, upon changing the order of mixing the individual components of the ternary systems (e.g., C-(A-)S-H phases synthesized in absence or presence of U(VI) and/or organics), along with results from spectroscopies, to derive mechanistic understanding of retention processes as well as surface complex models.

Keywords: uranium; C-S-H; C-A-S-H; hydrothermal synthesis; luminescence; spectroscopy

  • Lecture (Conference)
    Joint 6th International Workshop on Mechanisms and Modelling of Waste / Cement Interactions, 20.-22.11.2023, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-37936
Publ.-Id: 37936


Von Hochleistungslasern und Plasmen zum kompakten Protonen-Beschleuniger für radiobiologische Studien

Metzkes-Ng, J.

Die Methode zur Verstärkung sogenannter gechirpter Laserpulse wurde im Jahr 2018 mit dem Physik-Nobelpreis ausgezeichnet. Basierend auf dieser Methode lassen sich nun Laseranlagen mit Leistungen im Bereich von mehreren Petawatt realisieren. Werden die ultrakurzen Laserpulse eines solchen Hochleistungslasers auf dünne Metall- oder Plastikfolien fokussiert, können auf einer Strecke von wenigen Mikrometern intensive Ionenpulse beschleunigt werden. Bei der Wechselwirkung von Laserpuls und Folie entsteht dabei ein Plasma, in dem die Laserenergie zuerst auf schnelle Elektronen übertragen wird. Deren kollektive Felder bewirken dann die Beschleunigung von Ionen – das Prinzip eines Laser-Plasma-Beschleunigers. Besonders effektiv ist dieser Prozess für Protonen, die sich aktuell auf Energien jenseits der 100 MeV beschleunigen lassen.
Neben der Möglichkeit, kompakte Beschleuniger bauen zu können, punkten Laser-Plasma-Beschleuniger durch eine weitere besondere Eigenschaft: ihre Strahlen sind sehr intensiv und in Pikosekundenlänge gepulst, sodass ultrahohe Dosisleistungen erreicht werden. Davon kann die translationalen Krebsforschung profitieren – also jenes Forschungsgebiet, in dem Resultate der Grundlagenforschung auf neue Ansätze zur Prävention, Diagnostik und Behandlung von Krebserkrankungen übertragen werden. Die radiobiologische Wirkung stark gepulster Strahlung stellt hier nämlich eine aktuell intensiv diskutierte Fragestellung dar.
An der Realisierung einer Plattform für Radiobiologie mit ultrahohen Dosisraten basieren auf einem Laser-Plasma-Beschleuniger wird am Helmholtz-Zentrum Dresden—Rossendorf seit mehr als 15 Jahren gearbeitet. 2020 ist es hier nun erstmals gelungen, Tumoren in einem Kleintiermodell kontrolliert mit laserbeschleunigten Protonen zu bestrahlen. Bisherige Untersuchungen beschränkten sich auf Zellkulturen. Über viele Jahre wurden dazu der Laser, der Beschleunigungsmechanismus und das radiobiologische Modell studiert und optimiert, um bisherige Limitierungen bezüglich Protonenenergie und Beschleunigerstabilität zu überwinden und schließlich den Schritt von der Petrischale hin zum lebenden Modell wagen zu können. Die Ergebnisse markieren einen Meilenstein für die Entwicklung zuverlässiger Laser-Plasma-Beschleuniger und ermöglichen neuartige radiobiologische Studien.

Keywords: Laser-Protonenbeschleunigung

  • Invited lecture (Conferences)
    Festkolloquium 25 Jahre Medizinische Physik an der Martin-Luther-Universität Halle-Wittenberg, 23.11.2023, Halle (Saale), Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37935
Publ.-Id: 37935


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