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41396 Publications

Phase evolution of Te-hyperdoped Si upon furnace annealing

Shaikh, M. S.; Wang, M.; Hübner, R.; Liedke, M. O.; Butterling, M.; Solonenko, D.; Madeira, T. I.; Li, Z.; Xie, Y.; Hirschmann, E.; Wagner, A.; Zahn, D. R. T.; Helm, M.; Zhou, S.

Si hyperdoped with chalcogens via ion implantation and pulsed laser melting is known to exhibit strong room-temperature sub-bandgap photoresponse. As a thermodynamically metastable system, an impairment of the optoelectronic properties in hyperdoped Si materials occurs upon subsequent high-temperature thermal treatment (>500 °C). The substitutional Te atoms that cause the sub-bandgap absorption are removed from the Si matrix to form Te-related complexes, which are electrically and optically inactive. In this work, we explore the formation of defects in Te-hyperdoped Si layers which leads to the electrical deactivation upon furnace annealing through the analysis of optical and microstructural properties as well as positron annihilation lifetime spectroscopy. Particularly, Te-rich clusters are observed in samples thermally annealed at temperatures reaching 950 °C and above. Combined with polarized Raman analysis and transmission electron microscopy, the observed crystalline clusters are suggested to be Si2Te3.

Keywords: Defect analysis; Furnace annealing; Ion-implantation; Positron annihilation spectroscopy; Raman spectroscopy; Silicon telluride; Te-hyperdoped Si; Transmission electron microscopy

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Permalink: https://www.hzdr.de/publications/Publ-33082
Publ.-Id: 33082


Strain-induced switching between noncollinear and collinear spin configuration in magnetic Mn5Ge3 films

Xie, Y.; Yuan, Y.; Birowska, M.; Zhang, C.; Cao, L.; Wang, M.; Grenzer, J.; Kriegner, D.; Doležal, P.; Zeng, Y.-J.; Zhang, X.; Helm, M.; Zhou, S.; Prucnal, S.

We report the temperature-dependent magnetic and structural properties of epitaxial Mn5Ge3 thin films grown
on Ge substrates. Utilizing density-functional theory (DFT) calculations and various experimental methods, we
reveal mechanisms governing the switching between collinear and noncollinear spin configuration in Mn5Ge3.
The Mn atoms in Mn5Ge3 occupy two distinct Wyckoff positions with fourfold (Mn1) and sixfold (Mn2)
multiplicity. The DFT calculations reveal that below a critical distance of approximately 3.002 Å the coupling
between Mn2 atoms is antiferromagnetic (AFM) while ferromagnetic (FM) above that critical distance. The FM
coupling between Mn1 atoms is weakly affected by the strain. The observed noncollinear spin configuration is
due to the coexistence of AFM and FM coupling at low temperatures. The findings give insight in developing
strain-controlled spintronic devices.

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Permalink: https://www.hzdr.de/publications/Publ-33081
Publ.-Id: 33081


Interfacial Synthesis of Layer-Oriented 2D Conjugated Metal-Organic Framework Films toward Directional Charge Transport

Wang, Z.; Walter, L. S.; Wang, M.; Petkov, P. S.; Liang, B.; Qi, H.; Ngan Nguyen, N.; Hambsch, M.; Zhong, H.; Wang, M.; Park, S.; Renn, L.; Watanabe, K.; Taniguchi, T.; Mannsfeld, S. C. B.; Heine, T.; Kaiser, U.; Zhou, S.; Weitz, T. R.; Feng, X.; Dong, R.

The development of layer-oriented two-dimensional conjugated metal-organic frameworks (2D c-MOFs) enables access to direct charge transport, dial-in lateral/vertical electronic devices, and the unveiling of transport mechanisms but remains a significant synthetic challenge. Here we report the novel synthesis of metal-phthalocyanine-based p-type semiconducting 2D c-MOF films (Cu2[PcM-O8], M = Cu or Fe) with an unprecedented edge-on layer orientation at the air/water interface. The edge-on structure formation is guided by the preorganization of metal-phthalocyanine ligands, whose basal plane is perpendicular to the water surface due to their π-πinteraction and hydrophobicity. Benefiting from the unique layer orientation, we are able to investigate the lateral and vertical conductivities by DC methods and thus demonstrate an anisotropic charge transport in the resulting Cu2[PcCu-O8] film. The directional conductivity studies combined with theoretical calculation identify that the intrinsic conductivity is dominated by charge transfer along the interlayer pathway. Moreover, a macroscopic (cm2 size) Hall-effect measurement reveals a Hall mobility of ∼4.4 cm2 V-1 s-1 for the obtained Cu2[PcCu-O8] film. The orientation control in semiconducting 2D c-MOFs will enable the development of various optoelectronic applications and the exploration of unique transport properties.

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Permalink: https://www.hzdr.de/publications/Publ-33080
Publ.-Id: 33080


Physicochemical constraints on indium-, tin-, germanium-, gallium-, gold-, and tellurium-bearing mineralizations in the Pefka and St Philippos polymetallic vein- and breccia-type deposits, Greece

Voudouris, P.; Repstock, A.; Spry, P. G.; Frenzel, M.; Mavrogonatos, C.; Keith, M.; Tarantola, A.; Melfos, V.; Tombros, S.; Zhai, D.; Cook, N. J.; Ciobanu, C. L.; Schaarschmidt, A.; Rieck, B.; Kolitsch, U.; Falkenberg, J. J.

The Pefka Cu-Au-Te-In-Se and nearby St Philippos Pb-Zn-Bi-Sn-Ge-Ga-In vein- and breccia-type deposits in western Thrace, Greece, display strong similarities, but also differences in terms of mineralization style, ore mineralogy, and chemistry, and host rock compositions. The Pefka mineralization consists of two crosscutting vein systems with high sulfidation (HS)- and intermediate-sulfidation (IS) assemblages hosted by andesitic lavas and is unusually enriched in In (up to 700 ppm), Te (>1000 ppm), Se (>100 ppm), and Cu (>1 wt%). The main In-carriers are roquesite (CuInS2) and In-bearing “tennantite-(Cu)” and Cu-rich “tennantite-(In)” which contains up to 6.5 wt% In, substituting into the C site. Roquesite is associated with enargite and arsenosulvanite/colusite, as part of the HS assemblage at Pefka. Selenium-bearing galena and a large suite of tellurides including calaverite, sylvanite, petzite, hessite, kostovite, empressite, tellurantimony, and coloradoite, in addition to native tellurium, account for the marked tellurium and selenium enrichment in the ores from Pefka. Tellurides and native gold at Pefka accompany the precipitation of Te-bearing minerals of the tetrahedrite group, such as “stibiogoldfieldite” and “arsenogoldfieldite”, and Cu-excess varieties of tetrahedrite and tennantite. However, the bulk of telluride deposition is associated with normal, fully substituted tetrahedrite-tennantite varieties.

The St Philippos deposit is associated with a brecciated fault zone hosted by Eocene sandstones and Oligocene quartz-feldspar porphyry dikes. It is enriched in a large suite of incompatible elements, including Bi (>2000 ppm), Sn (>100 ppm), U (up to 200 ppm), Pb (>1 wt%), Zn (>1 wt%), Mo (up to 62 ppm), Ge (>100 ppm), Ga (up to 466 ppm) and In (up to 222 ppm), contrasting with the element suite defining the nearby Pefka deposit. The main carrier of In, Ga, and Ge is sphalerite (and wurtzite) with In-rich zones in sphalerite containing up to 6.1. wt% In. Germanium and Ga in sphalerite reach concentrations of up to 0.27 and 0.32 wt%, respectively. Sphalerite from the St Philippos deposit is extremely Fe-poor (<0.04 wt%), and is associated with an unusual suite of Sn-bearing sulfosalts (kësterite-stannite, Mn-bearing kësterite, unnamed Cu2MnSnS4), and enargite, marking an early HS event. Kësterite also hosts indium (up to 0.6 wt% In). Mn-bearing varieties of tennantite host inclusions of minor tellurides (e.g., hessite, altaite, and tsumoite) and formed later in the paragenetic sequence under transitional HS-IS and IS conditions.

Both deposits are characterized by early high-temperature (>300 °C) and HS fluid conditions, followed by IS assemblages as temperatures waned. Rhyolitic oxidized magmas are considered to be the sources of metals in the St Philippos deposit; however, their anomalous W, Sn, U, and Bi contents suggest a contamination by crustal rocks. The Cu-Au-Te signature of the Pefka deposit is compatible with a genetic relationship to less fractionated andesitic magmas, although a possible contribution of In from rhyolitic magmas could explain the high In contents of the ore. However, other factors, as for example different metal-deposition mechanisms resulting in metal zonation around causative porphyry centers at depth, may also account for the observed metal endowment in these two deposits. The Sn-Te-In-(Ge-Ga) element association at Pefka and St Philippos is unusual in that it has been previously reported from only a few other places in the world (e.g., Capillitas deposit, Argentina, and the Kawazu deposit, Japan). We conclude based on this exotic mineralization-style that the northeastern part of Greece represents an area of great potential for the exploitation of critical metals and metalloids.

Keywords: Critical metals; Greece; High-intermediate sulfidation; Magmatic-hydrothermal

Permalink: https://www.hzdr.de/publications/Publ-33079
Publ.-Id: 33079


Charge distribution in U1-xCexO2+y nanoparticles

Prieur, D.; Vigier, J.-F.; Popa, K.; Walter, O.; Dieste, O.; Varga, Z.; Beck, A.; Vitova, T.; Scheinost, A.; Martin, P.

In view of a safe management of the nuclear wastes, a sound knowledge of the atomic-scale properties of U1-xMxO2+y nanoparticles is essential. In particular, their cation valences and oxygen stoichiometries are of great interest as these properties drive their diffusion and migration behaviour into the environment. Here, we present an in-depth study of U1-xCexO2+y, over the full compositional domain, by combining XRD and HERFD-XANES. We show on one hand the co-existence of UIV, UV and UVI and on the other hand that the fluorite structure is maintained despite this charge distribution.

Keywords: Uranium; UO2; CeO2; HERD-XANES

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Permalink: https://www.hzdr.de/publications/Publ-33078
Publ.-Id: 33078


Probing charged lepton flavor violation with the Mu2e experiment

Müller, S.; Ferrari, A.; Knodel, O.; Rachamin, R.

Presentation a 2021 DPG meeting (section "Matter & Cosmos"), September1, 2021

Keywords: MU2E; Charged Lepton Flavor Violation; DPG

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  • Lecture (Conference) (Online presentation)
    DPG Meeting SMUK, 30.08.-03.09.2021, virtuell, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-33077
Publ.-Id: 33077


Checkliste zur Unterstützung der Helmholtz-Zentren bei der Implementierung von Richtlinien für nachhaltige Forschungssoftware

Messerschmidt, R.; Pampel, H.; Bach, F.; Zu Castell, W.; Denker, M.; Finke, A.; Fritzsch, B.; Hammitzsch, M.; Konrad, U.; Leifels, J.; Möhl, C.; Nolden, M.; Scheinert, M.; Schlauch, T.; Schnicke, T.; Steglich, D.

Mit der voranschreitenden Digitalisierung von Forschung und Lehre steigt die Zahl an Software-Lösungen, die an wissenschaftlichen Einrichtungen entstehen und zur Erkenntnisgewinnung genutzt werden. Die – unter dem Stichwort Open Science geforderte – Zugänglichkeit und Nachnutzung von wissenschaftlichen Ergebnissen kann in vielen Fachgebieten nur sichergestellt werden, wenn neben Forschungsdaten auch Programmcode offen zugänglich gemacht wird. Die vorliegende Handreichung richtet sich an Entscheider*innen in den Helmholtz-Zentren, die sich mit der Implementierung von Richtlinien für nachhaltige Forschungssoftware befassen. Sie ergänzt eine Muster-Richtlinie, die den Zentren bereits eine richtungsweisende und nachnutzbare Vorlage zur Erstellung von Regelungen für einen nachhaltigen Umgang mit Forschungssoftware gibt.

Keywords: Research Software; Open Access; Checkliste; Regelung; Software Policy

Permalink: https://www.hzdr.de/publications/Publ-33076
Publ.-Id: 33076


Models for translational proton radiobiology-from bench to bedside and back

Suckert, T.; Nexhipi, S.; Dietrich, A.; Koch, R.; Kunz-Schughart, L. A.; Bahn, E.; Beyreuther, E.

The number of proton therapy centers worldwide are increasing steadily, with more than two million cancer patients treated so far. Despite this development, pending questions on proton radiobiology still call for basic and translational preclinical research. Open issues are the on-going discussion on an energy-dependent varying proton RBE (relative biological effectiveness), a better characterization of normal tissue side effects and combination treatments with drugs originally de- veloped for photon therapy. At the same time, novel possibilities arise, such as radioimmunotherapy, and new proton therapy schemata, such as FLASH irradiation and proton mini-beams. The study of those aspects demands for radiobiological models at different stages along the translational chain, allowing the investigation of mechanisms from the molecular level to whole organisms. Focusing on the challenges and specifics of proton research, this review summarizes the different available models, ranging from in vitro systems to animal studies of increasing complexity as well as complementing in silico approaches.

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Permalink: https://www.hzdr.de/publications/Publ-33075
Publ.-Id: 33075


Not just a background: pH buffers do interact with lanthanide ions – a Europium(III) case study

Mandal, P.; Kretzschmar, J.; Drobot, B.

The interaction between Eu(III) ion and different pH buffers, popular in biology and biochemistry viz. HEPES, PIPES, MES, MOPS, and TRIS have been studied by solution nuclear magnetic resonance spectroscopy (NMR) and time-resolved laser-induced fluorescence spectroscopy (TRLFS) techniques. The Good’s buffers reveal non-negligible interaction with Eu(III) as determined from their complex stability constants, where the sites of interaction are the morpholine and piperazine nitrogen atoms, respectively. In contrast, TRIS buffer shows practically no affinity towards Eu(III). Therefore, when investigating lanthanides, TRIS buffer should be preferred over Good’s buffers.

Keywords: Europium; Buffer; TRLFS; NMR; Stability Constant

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Permalink: https://www.hzdr.de/publications/Publ-33074
Publ.-Id: 33074


ARIEL - Accelerator and Research reactor Infrastructures for Education and Learning

Beyer, R.; Junghans, A.

Status and news from ARIEL

Keywords: ARIEL; nELBE

Related publications

  • Invited lecture (Conferences) (Online presentation)
    ENEN Special Event 2021 - Outlook of nuclear ETKM activities, 03.03.2021, Brussels, Belgium

Permalink: https://www.hzdr.de/publications/Publ-33073
Publ.-Id: 33073


The nELBE neutron time-of-flight facility

Beyer, R.; Junghans, A.; Kögler, T.; Schwengner, R.; Urlaß, S.; Wagner, A.

The neutron time-of-flight facility nELBE at Helmholtz-Zentrum Dresden-Rossendorf features the first photo-neutron source at a superconducting electron accelerator. The electrons are focused onto a liquid lead target to produce bremsstrahlung which in turn produces neutrons via photo-nuclear reactions. The emitted neutron spectrum ranges from about 10 keV up to 15 MeV with a source strength of above 10¹¹ neutrons per second. The very precise time structure of the accelerator with a bunch width of a few ps enables time-of-flight measurements at very short flight path and experiments to investigate the time response of novel detector concepts.
The high repetition rate of 100 to 400 kHz in combination with the low instantaneous flux and the absence of any moderating materials provide favorable background conditions.
The very flexible beam properties at nELBE enable a broad range of nuclear physics experiments. Examples for the versatility of nELBE will be presented: From transmission measurements and inelastic neutron scattering and fission experiments to determine nuclear reaction cross sections with relevance for fundamental nuclear physics, reactor safety calculations, nuclear transmutation or particle therapy to experiments to investigate the response of novel particle detectors e.g. for dark matter search experiments, nuclear instrumentation or the range verification in cancer treatment.

Related publications

  • Poster (Online presentation)
    The 7th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications ANIMMA 2021, 21.-25.06.2021, Prague, Czech Republic
  • Lecture (Conference) (Online presentation)
    The 7th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications ANIMMA 2021, 21.-25.06.2021, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-33072
Publ.-Id: 33072


Total neutron cross section for ¹⁸¹Ta

Matic, A.; Beyer, R.; Birgersson, E.; Ferrari, A.; Grosse, E.; Junghans, A.; Schilling, K.-D.; Schwengner, R.; Wagner, A.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Mosconi, M.; Nolte, R.

The neutron time of flight facility nELBE, produces fast neutrons in the energy range from 0.1 MeV to 10 MeV by impinging a pulsed relativistic electron beam on a liquid lead circuit. The short beam pulses (∼10 ps) and a small radiator volume give an energy resolution better than 1% at 1 MeV using a short flight path of about 6 m, for neutron TOF measurements. The present neutron source provides 2 ⋅ 10⁴  n/cm²s at the target position using an electron charge of 77 pC and 100 kHz pulse repetition rate. This neutron intensity enables to measure neutron total cross section with a 2%–5% statistical uncertainty within a few days. In February 2008, neutron radiator, plastic detector and data acquisition system were tested by measurements of the neutron total cross section for ¹⁸¹Ta and ²⁷Al. Measurement of ¹⁸¹Ta was chosen because lack of high quality data in an energy region below 700 keV. The total neutron cross – section for ²⁷Al was measured as a control target, since there exists data for ²⁷Al with high resolution and low statistical error.

Keywords: nELBE; neutron transmission

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Permalink: https://www.hzdr.de/publications/Publ-33071
Publ.-Id: 33071


Single Particle Detection System for Strong-Field QED Experiments

Salgado, F. C.; Cavanagh, N.; Tamburini, M.; Storey, D. W.; Beyer, R.; Bucksbaum, P. H.; Chen, Z.; Piazza, A. D.; Gerstmayr, E.; Harsh; Junghans, A.; Keitel, C. H.; Kuschel, S.; Nielsen, C. F.; Reis, D. A.; Roedel, C.; Sarri, G.; Seidel, A.; Schneider, C.; Uggerhøj, U. I.; Wulff, J.; Yakimenko, V.; Zepter, C.; Meuren, S.; Zepf, M.; Isele, E.

Measuring signatures of strong-field quantum electrodynamics (SF-QED) processes in an intense laser field is an experimental challenge: it requires detectors to be highly sensitive to single electrons and positrons in the presence of the typically very strong x-ray and γ-photon background levels. In this paper, we describe a particle detector capable of diagnosing single leptons from SF-QED interactions and discuss the background level simulations for the upcoming Experiment-320 at FACET-II (SLAC National Accelerator Laboratory). The single particle detection system described here combines pixelated scintillation LYSO screens and a Cherenkov calorimeter. We detail the performance of the system using simulations and a calibration of the Cherenkov
detector at the ELBE accelerator. Single 3 GeV leptons are expected to produce approximately 537 detectable photons in a single calorimeter channel. This signal is compared to Monte-Carlo simulations of the experiment. A signal-to-noise ratio of 15 in a single Cherenkov calorimeter detector is expected and a spectral resolution of 2 % is achieved using the pixelated LYSO screens.

Keywords: strong-field QED; pair-creation; single-particle detection; Cherenkov calorimeter; Breit-Wheeler process; ELBE

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Permalink: https://www.hzdr.de/publications/Publ-33070
Publ.-Id: 33070


Synthesis, characterisation, and crystal structure of a novel U(V) brannerite UTi1.23Al0.77O6 and the UTi2-xAlxO6 system

Dixon Wilkins, M. C.; Mottram, L. M.; Maddrell, E. R.; Stennett, M. C.; Corkhill, C. L.; Kvashnina, K. O.; Hyatt, N. C.

The synthesis, characterisation and crystal structure of a novel U5+ (dominant) brannerite of composition U1.09(6)Ti1.29(3)Al0.71(3)O6 is reported, as determined from Rietveld analysis of high resolution powder neutron diffraction data. Examination of the UTi2-xAlxO6 system demonstrated the formation of brannerite structured compounds with varying Al3+ and U5+ content, from U0.93(6)Ti1.64(3)Al0.36(3)O6 to U0.89(6)Ti1.00(3)Al1.00(3)O6. Substitution of Al3+for Ti4+, with U5+ charge compensation, resulted in near-linear changes in the b and c unit cell parameters and the overall unit cell volume, as expected from ionic radii considerations. The presence of U5+ as the dominant oxidation state in near single phase brannerite compositions was evidenced by complementary laboratory U L3 edge and high energy resolution fluorescence detected (HERFD) U M4 edge X-ray Absorption Near Edge Spectroscopy. No brannerite phase was found for compositions with Al3+ / Ti4+ > 1, which would require U6+ contribution for charge compensation. These data expand the crystal chemistry of uranium brannerites to the stabilisation of dominant U5+ brannerites by substitution of trivalent cations, such as Al3+, on the Ti4+ site

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Permalink: https://www.hzdr.de/publications/Publ-33069
Publ.-Id: 33069


High energy resolution X-ray spectroscopy at actinide M4,5 and ligand K edges: what we know, what we want to know, what we can know

Kvashnina, K. O.; Butorin, S. M.

In recent years, scientists have progressively recognized the role of electronic structure in the characterization of chemical properties for actinide containing materials. High energy resolution X-ray spectroscopy at the actinide M4,5 edges emerged as a promising direction because this method can probe actinide properties at the atomic level through the possibility of reducing the experimental spectral width below the natural core-hole life time broadening. Parallel to the technical developments of the X-ray method and experimental discoveries, theoretical models, describing the observed electronic structure phenomena, have also advanced. In this feature article, we describe the latest progress in the field of high energy resolution X-ray spectroscopy at the actinide M4,5 and ligand K edges and we show that the methods are able to a) provide fingerprint information on the actinide oxidation state and ground state character b) probe 5f occupancy, non-stoichiometry, defects, ligand/metal ratio c) investigate the local symmetry and effects of the crystal field. We discuss the chemical aspects of the electronic structure in terms familiar to chemists and materials scientists and conclude with a brief description of new opportunities and approaches to improve the experimental methodology and theoretical analysis for the f-electron systems

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Permalink: https://www.hzdr.de/publications/Publ-33068
Publ.-Id: 33068


The Contribution of Manure Utilisation in Biogas Plants in Terms of Climate Change

Eggemann, L.; Rau, F.; Stolten, D.

The main source of global CO2 is heat and electricity production, which requires an increase in renewables that cover fluctuating sources. Biogas plants are one possibility, which are already commonly used in the European energy system. This study focuses on the utilisation of raw manure to reduce direct emissions of methane within an advanced and expensive, and a simplified and less expensive plant. Therefore, the environmental impact in terms of CO2 eq emissions of a biogas plant with either subsequent combustion in an internal combustion engine or the direct use of the biogas in a simplified burner are investigated. The analysis shows that the more advanced system yields 493 t CO2 eq, while the simplified one causes 42 t CO2 eq per year. Nevertheless, increasing average annual temperatures generate higher manure credits and thus reduce emissions of both plant options to 726 and -178 t CO2 eq per year, respectively, making the direct biogas usage become more interesting. Thus, both systems hold the potential for savings in terms of improved manure management against the background of climate change.

Keywords: renewable/green energy resources; advanced energy technologies; energy conservation in buildings; energy systems for power generation; environment and climate change

  • Lecture (Conference) (Online presentation)
    International Conference on Applied Energy 2021, 29.11.-02.12.2021, online, online

Permalink: https://www.hzdr.de/publications/Publ-33067
Publ.-Id: 33067


18F-Fluorodeoxyglucose Positron Emission Tomography of Head and Neck Cancer: Location and HPV Specific Parameters for Potential Treatment Individualization

Zschaeck, S.; Weingärtner, J.; Lombardo, E.; Marschner, S.; Hajiyianni, M.; Beck, M.; Zips, D.; Li, Y.; Lin, Q.; Amthauer, H.; Troost, E. G. C.; van den Hoff, J.; Budach, V.; Kotzerke, J.; Ferentinos, K.; Karagiannis, E.; Kaul, D.; Gregoire, V.; Holzgreve, A.; Albert, N. L.; Nikulin, P.; Bachmann, M.; Kopka, K.; Krause, M.; Baumann, M.; Kazmierska, J.; Cegla, P.; Cholewinski, W.; Strouthos, I.; Zöphel, K.; Majchrzak, E.; Landry, G.; Belka, C.; Stromberger, C.; Hofheinz, F.

Purpose
18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is utilized for staging and treatment planning of head and neck squamous cell carcinomas (HNSCC). Some older publications on the prognostic relevance showed inconclusive results, most probably due to small study sizes. This study evaluates the prognostic and potentially predictive value of FDG-PET in a large multi-center analysis.
Methods
Original analysis of individual FDG-PET and patient data from 16 international centers (8 institutional datasets, 8 public repositories) with 1104 patients. All patients received curative intent radiotherapy/chemoradiation (CRT) and pre-treatment FDG-PET imaging. Primary tumors were semi-automatically delineated for calculation of SUVmax, SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Cox regression analyses were performed for event-free survival (EFS), overall survival (OS), loco-regional control (LRC) and freedom from distant metastases (FFDM).
Results
FDG-PET parameters were associated with patient outcome in the whole cohort regarding clinical endpoints (EFS, OS, LRC, FFDM), in uni- and multivariate Cox regression analyses. Several previously published cut-off values were successfully validated. Subgroup analyses identified tumor- and human papillomavirus (HPV) specific parameters. In HPV positive oropharynx cancer (OPC) SUVmax was well suited to identify patients with excellent LRC for organ preservation. Patients with SUVmax of 14 or less were unlikely to develop loco-regional recurrence after definitive CRT. In contrast FDG PET parameters deliver only limited prognostic information in laryngeal cancer.
Conclusion
FDG-PET parameters bear considerable prognostic value in HNSCC and potential predictive value in subgroups of patients, especially regarding treatment de-intensification and organ-preservation. The potential predictive value needs further validation in appropriate control groups. Further research on advanced imaging approaches including radiomics or artificial intelligence methods should implement the identified cut-off values as benchmark routine imaging parameters.

Keywords: head and neck squamous cell carcinoma (HNSCC); fluorodeoxyglucose positron emission tomography (FDG PET); radiotherapy; metabolic tumor volume (MTV); standardized uptake value (SUV)

Permalink: https://www.hzdr.de/publications/Publ-33065
Publ.-Id: 33065


Timing of native metal-arsenide (Ag-Bi-Co-Ni-As±U) veins in continental rift zones – In situ U-Pb geochronology of carbonates from the Erzgebirge/Krušné Hory province

Guilcher, M.; Albert, R.; Gerdes, A.; Gutzmer, J.; Burisch, M.

Hydrothermal native metal-arsenide (five-element or Ag-Bi-Co-Ni-As±U) veins are a globally occurring mineralization style, which is particularly prevalent across Central Europe. Due to the limited amount of geochronological data available, the timing and the detailed geodynamic setting in which this mineralization style formed remains insufficiently understood. To fill this gap in knowledge, we applied innovative LA-ICP-MS U-Pb geochronology on carbonates from six districts in the Erzgebirge/Krušné Hory province of Germany and Czech Republic in order to constrain the timing of ore formation in the context of the geodynamic framework of Central Europe. In situ U-Pb ages of twelve samples, including dolomite-ankerite, calcite, and siderite coeval with Ni-Co-Fe-arsenides, range from ~129 to ~86 Ma. The ages of native metal-arsenide and fluorite-barite-Pb-Zn veins from the same occurrence (Annaberg-Buchholz district) are found to be consistent with each other, providing new and direct geochronological evidence that these two styles of mineralization are genetically related and may form coevally within one hydrothermal system. Complemented with available geochronological data from other occurrences, the formation of native metal-arsenide assemblage in Central Europe can be related to continental rifting affiliated with the Mesozoic opening of the Atlantic and Alpine Tethys Oceans (~200–100 Ma). The youngest age of ~86 Ma coincide with basin inversion associated with the onset of Alpine compressional tectonics, which most likely terminates the conditions favorable for the formation of native metal-arsenide mineralization in Europe. The onset of native metal-arsenide formation in proximal positions to the main rift axis starts at ~230–200 Ma (Penninic Alps, Anti-Atlas). In contrast, it occurs systematically later with increasing distance to the rift axis – namely at ~200–130 Ma in intermediate (Schwarzwald, Odenwald, Spessart) and ~140–86 Ma in distal (Erzgebirge, Harz) positions to the main rift axis.

Keywords: Arsenide; Carbonate geochronology; Cobalt; Erzgebirge; Five-element mineralization; U-Pb LA-ICP

Permalink: https://www.hzdr.de/publications/Publ-33064
Publ.-Id: 33064


DFT Surrogate modeling with the Materials Learning Algorithms (MALA) – Theoretical Background

Fiedler, L.

MALA (Materials Learning Algorithms) is a data-driven framework to generate surrogate models of density functional theory calculations based on machine learning. Its purpose is to enable multiscale modeling by bypassing computationally expensive steps in state-of-the-art density functional simulations. In this talk, an overview over the theoretical background that enables estimation of physical quantities based on the local density of states (LDOS) is given.

Keywords: Density Functional Theory; Machine Learning

  • Open Access Logo Lecture (Conference) (Online presentation)
    (TD)DFT Student Seminar Series (#5), 03.08.2021, Newark, USA

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Permalink: https://www.hzdr.de/publications/Publ-33063
Publ.-Id: 33063


A spectroscopic hike in the U-O phase diagram

Prieur, D.; Desagulier, M.-M.; Neuville, D.; Guéneau, C.; Epifano, E.; Dardenne, K.; Rothe, J.; Martin, P.

The U-O phase diagram is of paramount interest for nuclear related applications and has therefore been extensively studied. Experimental data have been gathered to feed the thermodynamic calculations and achieve an optimization of the U-O system modelling. Although considered as well established, a critical assessment of this large body of experimental data is necessary, especially in light of the recent development of new techniques applicable to actinide materials. Here we show how in situ XANES is suitable and relevant for phase diagram determination. New experimental data points have been collected using this method and discussed in regard to the available data. Comparing our experimental data with thermodynamic calculations, we observe that the current version of the U-O phase diagram misses some experimental data in specific domains. This lack of experimental data generates inaccuracy in the model, which can be overcome using in situ XANES. Indeed, as shown in the paper, this method is suitable to collect experimental data in non-ambient conditions and for multiphasic system.

Keywords: UO2; in situ XANES; Thermodynamics; CALPHAD method

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Permalink: https://www.hzdr.de/publications/Publ-33062
Publ.-Id: 33062


Data publication: Efficient laser-driven proton and Bremsstrahlung generation from cluster-assembled foam targets

Prencipe, I.; Metzkes-Ng, J.; Pazzaglia, A.; Bernert, C.; Dellasega, D.; Fedeli, L.; Formenti, A.; Garten, M.; Kluge, T.; Kraft, S.; Laso García, A.; Maffini, A.; Obst-Hübl, L.; Rehwald, M.; Sobiella, M.; Zeil, K.; Schramm, U.; Cowan, T.; Passoni, M.

Archiving of raw and results data and scripts as describef in the associated paper

Keywords: laser-driven ion acceleration; laser-driven Bremsstrahlung generation; TNSA; near-critical density plasma; nanostructured targets; foam targets

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Permalink: https://www.hzdr.de/publications/Publ-33061
Publ.-Id: 33061


Cell voltage model for Li-Bi liquid metal batteries

Weber, N.; Duczek, C.; Horstmann, G. M.; Landgraf, S.; Nimtz, M.; Personnettaz, P.; Weier, T.; Sadoway, D. R.

Lithium-bismuth bimetallic cells are amongst the best explored liquid metal batteries. A simple and fast one-dimensional cell voltage model for such devices is presented. The equilibrium cell potential is obtained from a complex two-dimensional fit of data drawn from multiple studies of equilibrium cell potential and rendered congruent with the phase diagram. Likewise, several analytical and fit functions for the ohmic potential drop across the electrolyte are provided for different battery geometries. Mass transport overpotentials originating from the alloying of Li into Bi are modelled by solving a diffusion equation, either analytically or numerically, and accounting for the volume change of the positive electrode. The applicability and limitations of the model are finally illustrated in three distinct experimental settings.

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Permalink: https://www.hzdr.de/publications/Publ-33058
Publ.-Id: 33058


Scale-dependent anisotropy, energy transfer and intermittency in bubble-laden turbulent flows

Ma, T.; Ott, B.; Fröhlich, J.; Bragg, A.

Data from Direct Numerical Simulations of disperse bubbly flows in a vertical channel are used
to study the effect of the bubbles on the carrier-phase turbulence. We developed a new method,
based on an extension of the barycentric map approach, that allows to quantify and visualize the
anisotropy and componentiality of the flow at any scale. Using this we found that the bubbles
significantly enhance anisotropy in the flow at all scales compared with the unladen case, and
that for some bubble cases, very strong anisotropy persists down to the smallest scales of the
flow. The strongest anisotropy observed was for the cases involving small bubbles. Concerning
the energy transfer among the scales of the flow, our results indicate that for the bubble-laden
cases, the energy transfer is from large to small scales, just as for the unladen case. However,
there is evidence of an upscale transfer when considering the transfer of energy associated with
particular components of the velocity field. Although the direction of the energy transfer is the
same with and without the bubbles, the behaviour of the energy transfer is significantly modified
by the bubbles, suggesting that the bubbles play a strong role in altering the activity of the
nonlinear term in the flow. The skewness of the velocity increments also reveal a strong effect of
the bubbles on the flow, changing both its sign and magnitude compared with the single-phase
case. We also consider the normalized forms of the fourth-order structure functions, and the
results reveal that the introduction of bubbles into the flow strongly enhances intermittency in the
dissipation range, but suppresses it at larger scales. This strong enhancement of the dissipation
scale intermittency has significant implications for understanding how the bubbles might modify
the mixing properties of turbulent flows.

Keywords: turbulence; bubbly flows

Permalink: https://www.hzdr.de/publications/Publ-33057
Publ.-Id: 33057


CFD Study on the Physical Behavior of Flue Dust within an Industrial-Scale Copper Waste Heat Boiler

Schmidt, A.; Montenegro, V.; Reuter, M.; Charitos, A.; Stelter, M.; Richter, A.

The Flash Smelting Furnace (FSF) is one of the most common aggregates for primary smelting of copper concentrates. Its smooth operation depends on the availability and performance of the downstream Waste Heat Boiler (WHB). The WHB is especially sensitive to problems with its flue dust handling, such as formation of accretions, which can lead to downtime and equipment failures. Due to the limited accessibility and the harsh conditions of the WHB, experimental studies are challenging. Therefore, CFD simulations can be a promising option to increase the knowledge and evaluate several options. The present study investigates the physical behavior of flue dust within an industrial-scale WHB via a three-dimensional CFD model. Size-dependent particle sedimentation and the risk areas for flue dust accretions are predicted, finding good agreement with industrial experience and literature data. For making the evaluation of accretion risk zones possible, a new sticking function for flue dust is developed. The results are validated against dust samples. Finally, operational recommendations for minimizing flue dust accretions are derived.

Keywords: Flash Smelting Furnace; Waste Heat Boiler; Flue Dust; Dust Accretions; CFD

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Publ.-Id: 33056


Development of a three-dimensional CFD Model for the Estimation of Accretion Formation in an Industrial-Scale Copper Waste Heat Boiler

Schmidt, A.; Montenegro, V.; Reuter, M.; Stelter, M.; Richter, A.

While striving for a circular economy of metals, the Flash Smelting Furnace (FSF) is the most common and “green” aggregate for primary smelting of copper concentrates, because of already today low CO2-emissions compared to other smelting technologies. High dust carry-over often leads to problems with flue dust accretions in its subsequent cooling aggregate, the Waste Heat Boiler (WHB). Removing these accretions causes mechanical stress for the boiler tubes and can lead to extended downtime and maintenance. The WHB has a limited accessibility towards experimental studies because of its harsh process conditions. Hence, Computational Fluid Dynamics (CFD) models appear as convenient option for WHB studies and design, but are not used for the evaluation of flue dust accretions yet. For the inclusion of this feature into a three-dimensional CFD model of the entire WHB, a new sticking function is developed. It is based on the industrial experience that flue dust is only sticky above a certain softening temperature. Since the WHB has a varying dust input due to the flexible operation of the FSF, a parameter study is conducted for standard flue dust, pure copper oxide dust and pure iron oxide dust, finding minor sensitivity towards the flue dust density and no sensitivity towards the dust heat capacity. From these findings, recommendations for the minimization of flue dust accretion formation in the WHB are derived.

Keywords: Copper Production; Flash Smelting Furnace; Waste Heat Boiler; Flue Dust; Accretion Formation; 3D CFD

  • World of Metallurgy - Erzmetall 74(2021)5, 270-276

Permalink: https://www.hzdr.de/publications/Publ-33055
Publ.-Id: 33055


²⁶Al and ¹⁰Be in urban and Antarctic micrometeorites

Feige, J.; Airo, A.; Berger, D.; Brückner, D.; Genge, M.; Laya, I.; Habibi Marekani, F.; Klingner, N.; Lachner, J.; Nissen, J.; Patzer, A. B. C.; Schley, N.; Schropp, A.; Peterson, S.; Sager, C.; Suttle, M.; Trappitsch, R.; Weinhold, J.

Roughly 100 tons of extraterrestrial material released from asteroid collision events or cometary sublimation enter the Earth’s atmosphere each day. Some of this material reaches the surface as micrometeorites (MMs) – mostly submillimetre spherical melting droplets. For more than a century MMs were collected only in remote environments such as deep-sea sediments or Antarctic firn and ice. However, since 2017 significant numbers of MMs were found in urban areas, particularly on rooftops of buildings. In contrast to MMs originating from slow-accumulating environments that can have been deposited millions of years ago, the particles from the rooftops are not older than the buildings and currently are the youngest extraterrestrial particles ever collected.
The study of the irradiation histories of MMs provides an important step towards identifying the nature and origin of their parent bodies. During their million-year long journey on spiral trajectories to Earth, these small interplanetary particles are exposed to cosmic radiation producing long-lived radionuclides such as 26Al and 10Be.
Since the number of cosmogenic nuclides increases with the time the MMs travel through space it is possible to estimate from how far out in the Solar System they originated from. However, the very small amounts of a few million atoms of the radionuclides within a MM decrease after deposition on Earth, i.e., with increasing terrestrial age. Hence, urban MMs, with insignificant terrestrial ages, provide for the first time the opportunity to measure the highest possible concentrations of long-lived radionuclides within MMs.
We analyzed six urban MMs and, for comparison with MMs that have terrestrial ages up to 780 kyr, six MMs collected from Antarctic Moraine sediments for their 26Al and 10Be content. The MMs with sizes of 90-500 µm were dissolved and, after stable carrier addition, 10Be an 26Al were chemically extracted and measured with AMS at the Vienna Environmental Research Accelerator (VERA), Vienna, Austria. These experimental data were compared to results from numerical simulations yielding 26Al and 10Be concentrations in micrometeoroids having various orbital parameters, compositions, and irradiation profiles.
The 26Al/27Al and 10Be/9Be measurement results were significantly above the chemistry blank values, except for the smallest (90 µm) Antarctic MM. Conversion to 26Al and 10Be concentration yields values between 104 and 107 atoms per sample. Comparison with the theoretical data generally favours carbonaceous chondrite objects as the parent bodies of the MMs orbiting with several eccentricities within our Solar System.
Our results are influenced by the following assumptions: no pre-irradiation within the parent body, no mass loss during atmospheric entry, average carbonaceous or ordinary chondrite composition, no significant terrestrial ages, and the theoretical production rates for 26Al and 10Be are correct. Besides the use of additional methods such as mineralogical and isotope geochemical analysis better statistics of long-lived radionuclides within MMs may help to constrain some of these assumptions.

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  • Lecture (Conference) (Online presentation)
    The 15th International Conference on Accelerator Mass Spectrometry (AMS-15), 15.-19.11.2021, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-33054
Publ.-Id: 33054


Implementing Heterogeneous Crystal Surface Reactivity in Reactive Transport Simulations: The Example of Calcite Dissolution

Karimzadeh, L.; Fischer, C.

Both surface reactivity and fluid dynamics control the dissolution kinetics of crystalline material. In this study, we performed a 3D reactive transport simulation to investigate the impact of surface topography heterogeneity superimposed to fluid transport heterogeneity on the dissolution rate of calcite. The
model simulates the chemical reaction of calcite dissolution, solute transport, and crystal surface geometry evolution. Importantly, we introduce heterogeneous surface reactivity into the reactive transport simulation. We test the surface slope factor as a proxy value for the intrinsic surface reactivity of dissolving crystal surface nanotopographies. Experimental data sets collected using vertical scanning interferometry validate this approach. The novel parametrization allows for the simulation of surface-controlled heterogeneous reactivity in reactive transport simulations of mineral surface dissolution.

Keywords: reactive transport modeling; crystal surface reactivity; rate map; dissolution rate variability; calcite dissolution

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Permalink: https://www.hzdr.de/publications/Publ-33053
Publ.-Id: 33053


Multiscale modelling for fusion and fission materials: the M4F project

Malerba, L.; Caturla, M. J.; Gaganidze, E.; Kaden, C.; Konstantinović, M. J.; Olsson, P.; Robertson, C.; Rodney, D.; Ruiz-Moreno, A. M.; Serrano, M.; Aktaa, J.; Anento, N.; Austin, S.; Bakaev, A.; Balbuena, J. P.; Bergner, F.; Boioli, F.; Boleininger, M.; Bonny, G.; Castin, N.; Chapman, J. B. J.; Chekhonin, P.; Clozel, M.; Devincre, B.; Dupuy, L.; Diego, G.; Dudarev, S. L.; Fu, C. C.; Gatti, R.; Gélébart, L.; Gómez-Ferrer, B.; Gonçalves, D.; Guerrero, C.; Gueye, P. M.; Hähner, P.; Hannula, S. P.; Hayat, Q.; Hernández-Mayoral, M.; Jagielski, J.; Jennett, N.; Jiménez, F.; Kapoor, G.; Kraych, A.; Khvan, T.; Kurpaska, L.; Kuronen, A.; Kvashin, N.; Libera, O.; Ma, P. W.; Manninen, T.; Marinica, M. C.; Merino, S.; Meslin, E.; Mompiou, F.; Mota, F.; Namburi, H.; Ortiz, C. J.; Pareige, C.; Prester, M.; Rajakrishnan, R. R.; Sauzay, M.; Serra, A.; Simonovski, I.; Soisson, F.; Spätig, P.; Tanguy, D.; Terentyev, D.; Trebala, M.; Trochet, M.; Ulbricht, A.; Vallet, M.; Vogel, K.; Yalcinkaya, T.; Zhao, J.

The M4F project brings together the fusion and fission materials communities working on the prediction of radiation damage production and evolution and its effects on the mechanical behaviour of irradiated ferritic/martensitic (F/M) steels. It is a multidisciplinary project in which several different experimental and computational materials science tools are integrated to understand and model the complex phenomena associated with the formation and evolution of irradiation induced defects and their effects on the macroscopic behaviour of the target materials. In particular the project focuses on two specific aspects: (1) To develop physical understanding and predictive models of the origin and consequences of localised deformation under irradiation in F/M steels; (2) To develop good practices and possibly advance towards the definition of protocols for the use of ion irradiation as a tool to evaluate radiation effects on materials. Nineteen modelling codes across different scales are being used and developed and an experimental validation programme based on the examination of materials irradiated with neutrons and ions is being carried out. The project enters now its 4th year and is close to delivering high-quality results. This paper overviews the work performed so far within the project, highlighting its impact for fission and fusion materials science.

Permalink: https://www.hzdr.de/publications/Publ-33052
Publ.-Id: 33052


Pump-induced terahertz anisotropy in bilayer graphene

Seidl, A.; Anvari, R.; Dignam, M. M.; Richter, P.; Seyller, T.; Schneider, H.; Helm, M.; Winnerl, S.

We investigate the intraband nonlinear dynamics in doped bilayer graphene in the
presence of strong, linearly-polarized, in-plane terahertz fields. We perform degenerate
pump-probe experiments with 3.4 THz fields on doped bilayer graphene at low temper-
ature (12 K) and find that when the pump is co-polarized with the probe beam, the
differential pump-probe signal is almost double that found in the cross-polarized case.
We show that the origin of this pump-induced anisotropy is the difference in the aver-
age electron effective mass in the probe direction when carriers are displaced in k-space
by the pump either parallel or perpendicular to the direction of the probe polarization.
We model the system using both a simple semiclassical model and a Boltzmann equa-
tion simulation of the electron dynamics with phenomenological scattering and find
good qualitative agreement with experimental results.

Keywords: bilayer graphene; nonlinear; terahertz; anisotropy

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Publ.-Id: 33051


Metal–Insulator Transition via Ion Irradiation in Epitaxial La0.7Sr0.3MnO3-δ Thin Films

Cao, L.; Herklotz, A.; Rata, D.; Yin, C.; Petracic, O.; Kentsch, U.; Helm, M.; Zhou, S.

Complex oxides provide rich physics related to ionic defects. For the proper tuning of functionalities in oxide heterostructures, it is highly desired to develop fast, effective and low temperature routes for the dynamic modification of defect concentration and distribution. In this work, we report on the use of helium-implantation to efficiently control the vacancy profiles in epitaxial La0.7Sr0.3MnO3-δ thin films. The viability of this approach is supported by lattice expansion in the out-of-plane lattice direction and dramatic change in physical properties, i.e., a transition from ferromagnetic metallic to antiferromagnetic insulating. In particular, a significant increase of resistivity up to four orders of magnitude is evidenced at room temperature, upon implantation of highly energetic He-ions. Our result offers an attractive means for tuning the emergent physical properties of oxide thin films, via strong coupling between strain, defects and valence.

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Permalink: https://www.hzdr.de/publications/Publ-33050
Publ.-Id: 33050


APR files

Nour, A.

APR  files for 4 different functions

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Permalink: https://www.hzdr.de/publications/Publ-33049
Publ.-Id: 33049


Internal Access: Full source data of publication: "Tumor irradiation in mice with a laser-accelerated proton beam"

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

All source data and scripts for publication: "Tumor irradiation in mice with a laser-accelerated proton beam"

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

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Permalink: https://www.hzdr.de/publications/Publ-33048
Publ.-Id: 33048


Source Data: Tumour irradiation in mice with a laser-accelerated proton beam (Open Access)

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

Source data for all figures of publication: "Tumor irradiation in mice with a laser-accelerated proton beam". The folder structure is adapted to match the figures in the publication.

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

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Publ.-Id: 33047


Layer-Dependent Band Gaps of Platinum-Dichalcogenides

Li, J.; Kolekar, S.; Ghorbani Asl, M.; Lehnert, T.; Biskupek, J.; Kaiser, U.; Krasheninnikov, A.; Batzill, M.

Owing to the relatively strong inter-layer interaction, the platinum-dichalcogenides exhibit tunability of their electronic properties by controlling the number of layers. Both PtSe2 and PtTe2 display a semi-metal to semi-conductor transition as they are reduced to bi- or single-layer. The value of the fundamental band gap, however, has been inferred only from density functional theory (DFT) calculations, which are notoriously challenging, as different methods give different results, and currently there is no experimental data. Here we determine the band gap as a function of the number of layers by local scanning tunneling spectroscopy on MBE-grown PtSe2 and PtTe2 islands. We find band gaps of 1.8 eV and 0.6 eV for mono- and bi-layer PtSe2, respectively, and 0.5 eV for monolayer PtTe2. Tri-layer PtSe2 and bilayer PtTe2 are semi-metallic. The experimental data are compared to DFT calculations carried out at different levels of theory. The calculated band gaps may differ significantly from the experimental values, emphasizing the importance of the experimental work. We further show that the variations in the calculated fundamental band gap in bilayer PtSe2 are related to the computed separation of the layers, which depends on the choice of the van der Waals functional. This sensitivity of the band gap to inter-layer separation also suggests that the gap can be tuned by uniaxial stress and our simulations indicate that only modest pressures are required for a significant reduction of the gap, making Pt-dichalcogenides suitable materials for pressure-sensing.

Keywords: 2D materials; layer dependence; PtSe2; PtTe2; scanning tunneling spectroscopy; van der Waals materials; transition metal dichalcogenides

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Publ.-Id: 33046


Efficient laser-driven proton and Bremsstrahlung generation from cluster-assembled foam targets

Prencipe, I.; Metzkes-Ng, J.; Pazzaglia, A.; Bernert, C.; Dellasega, D.; Fedeli, L.; Formenti, A.; Garten, M.; Kluge, T.; Kraft, S.; Laso García, A.; Maffini, A.; Obst-Hübl, L.; Rehwald, M.; Sobiella, M.; Zeil, K.; Schramm, U.; Cowan, T.; Passoni, M.

The interaction between intense 30 fs laser pulses and foam-coated 1.5 μm-thick Al foils in the relativistic regime (up to
5x10²⁰ W/cm2) is studied to optimize the laser energy conversion into laser-accelerated protons. A significant enhancement is
observed for foam targets in terms of proton cut-off energy (18.5 MeV) and number of protons above 4.7 MeV (4x10⁹
protons/shot) with respect to uncoated foils (9.5 MeV, 1x10⁹ protons/shot), together with a sixfold increase in the
Bremsstrahlung yield. This enhancement is attributed to increased laser absorption and electron generation in the foam meso-
and nanostructure.

Keywords: laser-driven ion acceleration; laser-driven Bremsstrahlung generation; TNSA; near-critical density plasma; nanostructured targets; foam targets

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Permalink: https://www.hzdr.de/publications/Publ-33045
Publ.-Id: 33045


Tumor irradiation in mice with a laser-accelerated proton beam

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

Recent oncological studies identified beneficial properties of radiation applied at ultra-high dose rates several orders of magnitude higher than the clinical standard of the order of Gy/min. Sources capable of providing these ultra-high dose rates are under investigation. Here, we show that a stable, compact laser-driven proton source with energies greater than 60 MeV enables radiobiological in vivo studies. We performed a pilot irradiation study on human tumors in a mouse model, showing the concerted preparation of mice and laser accelerator, the dose-controlled, tumor-conform irradiation using a laser-driven as well as a clinical reference proton source, and the radiobiological evaluation of irradiated and unirradiated mice for radiation-induced tumor growth delay. The prescribed homogeneous dose of 4 Gy was precisely delivered at the laser-driven source. The results demonstrate a complete laser-driven proton research platform for diverse user-specific small animal models, able to deliver tunable single-shot doses up to around 20 Gy to millimeter-scale volumes on nanosecond time scales, equivalent to around 1E9 Gy/s, spatially homogenized and tailored to the sample. The platform provides a unique infrastructure for translational research with protons at ultra-high dose rate.

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

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Permalink: https://www.hzdr.de/publications/Publ-33044
Publ.-Id: 33044


Elektrische Energiespeicherung mit Flüssigmetallen und Salzschmelzen

Weier, T.; Horstmann, G. M.; Landgraf, S.; Personnettaz, P.; Stefani, F.; Weber, N.

Stationäre Elektroenergiespeicher können helfen, momentane Differenzen von Elektrizitätsangebot und -nachfrage zu balancieren. Mit zunehmender Nutzung volatiler Stromquellen wird diese Aufgabe wichtiger. Dabei stehen verschiedene Speichertechnologien untereinander,
aber auch mit Alternativen im Wettbewerb.
Flüssigmetallbatterien sind Hochtemperaturspeicher. Sie basieren
auf der stabilen Dichteschichtung eines Alkalimetalls, einer Salzschmelze und eines Schwermetalls. Vermittelt durch die hohe Betriebstemperatur, die über den Schmelztemperaturen der einzelnen Phasen liegen
muss, verlaufen Grenzflächenreaktionen und Transportvorgänge sehr
rasch, was in hohen Strom- und Leistungsdichten resultiert. Der vollständig flüssige Zellinhalt ermöglicht einerseits eine konzeptionell einfache Skalierbarkeit auf Zellebene, die sehr günstige energiebezogene
Investitionskosten verspricht. Andererseits gewinnen durch den flüssige Aggregatzustand strömungsmechanische Vorgänge, die eng an den
Ladungstransport und -übergang gekoppelt sind, stark an Bedeutung.
Der Vortrag wird sowohl ausgewählte physikalische Phänomene in
Flüssigmetallbatterien vorstellen, als auch ihre mögliche Rolle in einem
zukünftigen Energiesystem diskutieren.

Keywords: liquid metal batteries; energy storage

  • Invited lecture (Conferences) (Online presentation)
    84. Jahrestagung der DPG und DPG-Tagung der Sektion Kondensierte Materie, 27.09.-01.10.2021, virtuell, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-33043
Publ.-Id: 33043


Compositional convection in liquid metal electrodes

Personnettaz, P.; Klopper, T. S.; Benard, S.; Kubeil, C.; Landgraf, S.; Weber, N.; Weier, T.

Liquid metal electrodes are a crucial element of innovative electrochemical cells such as
liquid metal batteries (LMBs) and solutal - alkali metal thermal electric converters (S-AMTECs).
The liquid phase is a key to guarantee scalability, extended life time and high cyclability; at the same
time fluid mechanics plays a pivotal role in terms of cell capacity and efficiency. The geometry
of these electrodes is simple: a liquid metal alloy is confined by an electrochemically active interface
and inert walls. The active interface can be fluid (molten salt electrolyte) or solid (fast ionic
conductor). During operation of the cell a mass flux is established across the interface. The liquid
metal alloy experiences an enrichment or depletion of the electroactive species. This changes the
local density distribution and either induces or suppresses convective flows. Here, we focus
on the positive electrode of a liquid metal battery during the charging step. The electroactive species
(e.g. Li) is extracted from the alloy (e.g. Li(in Bi)), and the heavy alloy generated at the top interface
sinks down leading to strong compositional convection. The evolution of the concentration and
velocity fields are studied with numerical methods; the results of a finite volume code (OpenFOAM)
are compared with the ones of a spectral element code (SEMTEX). The effects of Schmidt number,
current density magnitude and distribution and electrode geometry are investigated. Furthermore,
the impact of a non-uniform temperature distribution and the mechanical coupling with a molten
salt layer are discussed.

Keywords: LMB; S-AMTEC; mass transport; solutal convection

  • Lecture (Conference) (Online presentation)
    IV Russian Conference on Magnetohydrodynamics, 20.-22.09.2021, Perm, Russia

Permalink: https://www.hzdr.de/publications/Publ-33042
Publ.-Id: 33042


Deposition of silicon oxide films on silicon using HelixJet – an atmospheric-pressure plasma jet process below 100 °C

Rebohle, L.; Quade, A.; Schumann, T.; Blaschke, D.; Hübner, R.; Heller, R.; Foest, R.; Schäfer, J.; Skorupa, W.

Silicon oxide films are widely applied for their superior dielectric, chemical and mechanic properties as well as for their resistance against reactive chemicals. Simultaneously, there is an increasing number of applications which demand a low deposition temperature. In this work, we compare the material properties of SiOx layers deposited at ca. 70°C by atmospheric-pressure plasma jet deposition (PA) with those of SiO2 layers thermally grown or deposited by plasma-enhanced chemical vapour deposition. The films were deposited on silicon wafers and analysed using different analysis techniques. According to cross-sectional transmission electron microscopy and high-frequency capacitance-voltage measurements, the interface between the PA oxide and the Si substrate is smooth with no apparent defects and displays an electrically active interface defect density between 3.5-8.0×1012 cm-2 directly after deposition and below 2.0×1012 cm-2 after furnace annealing. Right after deposition, the PA oxide contains carbon and hydrogen in a concentration of several at%, and the SiO2 plasma polymer network comprises several active centres (residual charge, free radicals, non-saturated bonds). The most abundant configuration is the Si(-O)4 tetrahedron, followed by Si(-O)3 with similar intensity. This indicates that there are still dangling Si bonds or bonds terminated by hydroxyl or methyl groups. After furnace annealing, the formation of the SiO2 network is completed and the optical and electrical properties of the PA oxide converge to that of thermal oxide.

Keywords: dielectric coating; insulation; corrosion protection; silicon oxide; atmospheric plasma source; thin films

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Permalink: https://www.hzdr.de/publications/Publ-33040
Publ.-Id: 33040


Data publication: Radiation damage evolution in pure W and W-Cr-Hf alloy caused by 5MeV Au ions in a broad range of dpa

Mackova, A.; Havranek, V.; Fernandes, S.; Matejicek, J.; Vilemova, M.; Holy, V.; Liedke, M. O.; Martan, J.; Vronka, M.; Potocek, M.; Babor, P.; Butterling, M.; Elsherif, A. G. A.; Hirschmann, E.; Wagner, A.

Positron annihilation lifetime spectroscopy data taking for ELBE proposal POS19101496 by Sandrina Fernandes, Rez, CZ. Role of open volume defects in irradiated structural materials for fusion applications. Measurements performed 16.3.2019 at the MePS facility.

Keywords: positron annihilation lifetime spectroscopy; SIMS; alloys; W Tungsten

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Permalink: https://www.hzdr.de/publications/Publ-33039
Publ.-Id: 33039


Rapid synthesis of gold-palladium core-shell aerogels for selective and robust electrochemical CO2 reduction

Du, R.; Jin, W.; Wu, H.; Hübner, R.; Zhou, L.; Xue, G.; Hu, Y.; Eychmüller, A.

Noble metal aerogels (NMAs), one class of the youngest members in the aerogel family, have drawn increasing attention in the last decade. Featuring the high catalytic activity of noble metals and a 3D self-supported porous network of the aerogels, they have displayed profound potential for electrocatalysis. However, considerable challenges reside in the rapid fabrication of NMAs with a well-tailored architecture, constraining the manipulation of their electrochemical properties for optimized performance. Here, a disturbance-assisted dynamic shelling strategy is developed, generating self-supported Au–Pd core–shell gels within 10 min. Based on suitable activation and desorption energies of the involved species as suggested by theoretical calculations, the Au–Pd core–shell aerogel manifests outstanding CO selectivity and stability at low overpotential (faradaic efficiency > 98% at -0.5 V vs. RHE over 12 hours) for the electrochemical CO2 reduction reaction (CO2RR). The present strategy offers a new perspective to facilely design architecture-specified high-performance electrocatalysts for the CO2RR.

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Permalink: https://www.hzdr.de/publications/Publ-33038
Publ.-Id: 33038


Integrated complementary inverters and ring oscillators based on vertical-channel dual-base organic thin-film transistors

Guo, E.; Xing, S.; Dollinger, F.; Hübner, R.; Wang, S.-J.; Wu, Z.; Leo, K.; Kleemann, H.

Lateral-channel dual-gate organic thin-film transistors have been used in pseudo complementary metal-oxide-semiconductor (CMOS) inverters to control switching voltage. However, their relatively long channel lengths, combined with the low charge carrier mobility of organic semiconductors, typically leads to slow inverter operation. Vertical-channel dual-gate organic thin-film transistors are a promising alternative because of their short channel lengths, but the lack of appropriate p- and n-type devices has limited the development of complementary inverter circuits. Here, we show that organic vertical n-channel permeable single- and dual-base transistors, and vertical p-channel permeable base transistors can be used to create integrated complementary inverters and ring oscillators. The vertical dual-base transistors enable switching voltage shift and gain enhancement. The inverters exhibit small switching time constants at 10 MHz, and the seven-stage complementary ring oscillators exhibit short signal propagation delays of 11 ns per stage at a supply voltage of 4 V.

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Permalink: https://www.hzdr.de/publications/Publ-33037
Publ.-Id: 33037


Data for: On Inter-bubble Distances and Bubble Clustering in Bubbly Flows: An Experimental Study

Kipping, R.; Hampel, U.

This data set contains the processed data from ultrafast X-ray tomography measurements in a bubble column. Measurements were performed in a bubble column with 100 mm inner diameter and with deionized water and nitrogen as liquid and gas phase, respectively. This data set contains the measurement from the measurement height located 0.7m above the gas sparger. 

Hydrodynamic data, such as bubble size distribution and gas holdup distribution are provided. Furthermore, inter-bubble distances of gas bubbles (distance of the nearest neighbours) are given.

Further detailes on the experiments and the processed data is provided in the corresponding journal paper.

Keywords: bubbly flows; clustering; UFXCT

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Permalink: https://www.hzdr.de/publications/Publ-33036
Publ.-Id: 33036


Data publication: FPGA-based Real-Time Data Acquisition for Ultrafast X-Ray Computed Tomography

Windisch, D.; Knodel, O.; Juckeland, G.; Hampel, U.; Bieberle, A.

This data contains the firmwares used for all descirbed tests in the paper.

Keywords: Computed tomography; Data acquisition; Field programmable gate arrays

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Permalink: https://www.hzdr.de/publications/Publ-33035
Publ.-Id: 33035


Evidence of collision-induced resuspension of microscopic particles from a monolayer deposit

Banari, A.; Henry, C.; Fank Eidt, R. H.; Pierre, L.; Klaus, Z.; Hampel, U.; Lecrivain, G.

The present Letter addresses the resuspension of microscopic glass particles from a monolayer bed into a turbulent gas flow. With an intermediate surface coverage, here set to about 10% of the field of view, we report two distinct detachment mechanisms. At relatively low flow velocities, few loosely adhering particles move on the wall to eventually collide with neighboring particles resulting in a clustered resuspension. At higher fluid velocities, mostly individual particles resuspend due to their interaction with the turbulent flow. The resuspension curve, showing the remaining particle fraction as a function of the flow velocity, exhibits a strong bimodal character.

Keywords: paticle resuspension; Inter-particle collisions; experimental test

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Permalink: https://www.hzdr.de/publications/Publ-33034
Publ.-Id: 33034


Fabrication and nanophotonic waveguide integration of silicon carbide colour centres with preserved spin-optical coherence

Babin, C.; Stöhr, R.; Morioka, N.; Linkewitz, T.; Steidl, T.; Wörnle, R.; Liu, D.; Hesselmeier, E.; Vorobyov, V.; Denisenko, A.; Hentschel, M.; Gobert, C.; Berwian, P.; Astakhov, G.; Knolle, W.; Majety, S.; Saha, P.; Radulaski, M.; Tien Son, N.; Ul-Hassan, J.; Kaiser, F.; Wrachtrup, J.

Optically addressable spin defects in silicon carbide (SiC) are an emerging platform for quantum information processing. Lending themselves to modern semiconductor nanofabrication, they promise scalable high-efficiency spin-photon interfaces. We demonstrate here nanoscale fabrication of silicon vacancy centres (VSi) in 4H-SiC without deterioration of their intrinsic spin-optical properties. In particular, we show nearly transform limited photon emission and record spin coherence times for single defects generated via ion implantation and in triangular cross section waveguides. For the latter, we show further controlled operations on nearby nuclear spin qubits, which is crucial for fault-tolerant quantum information distribution based on cavity quantum electrodynamics.

Keywords: Qubits; Silicon carbide; Quantum spintronics; Quantum photonics; Point defects

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Permalink: https://www.hzdr.de/publications/Publ-33033
Publ.-Id: 33033


Data and code for: A stable home: Autocorrelated Kernel Density Estimated home ranges of the critically endangered Elongated Tortoise

Montano, Y.; Michael Marshall, B.; Ward, M.; Simoes Silva, I. M.; Artchawakom, T.; Waengsothorn, S.; Strine, C. T.

Supplemental materials for A stable home: Autocorrelated Kernel Density Estimated home ranges of the critically endangered Elongated Tortoise on OSF Preprints, including data, code, figures and tables.

Keywords: ecology; testudine; autocorrelated kernel density estimator; spatial ecology; space use; Thailand; Indotestudo elongata

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  • Reseach data in external data repository
    Publication year 2021
    License: Creative Commons Attribution 4.0 International
    Hosted on OSF: Link to location

Permalink: https://www.hzdr.de/publications/Publ-33032
Publ.-Id: 33032


A stable home: Autocorrelated Kernel Density Estimated home ranges of the critically endangered Elongated Tortoise

Montano, Y.; Michael Marshall, B.; Ward, M.; Simoes Silva, I. M.; Artchawakom, T.; Waengsothorn, S.; Strine, C. T.

Home range is a fundamental concept in ecology used to describe animal space use over their lifetimes. Numerous studies use a variety of metrics to quantify home range; however, most of these treat spatial data inappropriately. Here we re-analyse a publicly available data-set, collected by the authors of this study, using a relatively novel and appropriate home range metric Autocorrelated Kernel Density Estimators (AKDE). Our data includes the movements of 17 Elongated Tortoises (Indotestudo elongata; 12 females, 5 males) located on average once every three days for an average duration of 353.76 ±33.10 days. We found 14 of 17 individuals appear to be occupying a stable home range (using variograms to determine range residency). We made use of AKDEs bias-mitigating measures to counteract the low effective sample sizes stemming from low temporal resolution radio-tracking data. The average AKDE home range for all 14 individuals with range residency was 44.81 ±10.44 ha. Bayesian Regression Models suggest considerable overlap between male and female home range estimates despite males being physically larger than females in both mass and carapace length. These home range estimates have the added utility of being comparable with other studies, less susceptible to errors from a suboptimal tracking regime, and are optimised with code and data for inclusion in future meta-analyses.

Keywords: ecology; testudine; autocorrelated kernel density estimator; spatial ecology; space use; Thailand; Indotestudo elongata

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Publ.-Id: 33031


Data and code for: Lots of movement, little progress: A review of reptile home range literature

Crane​, M.; Simoes Silva, I. M.; Marshall, B. M.; Strine​, C. T.

Datasets, R code and figures pertaining to the manuscript: Crane, M., Silva, I., Marshall, B. M., & Strine, C. T. (2021). Lots of movement, little progress: A review of reptile home range literature. PeerJ, 9, e11742. DOI: 10.7717/peerj.11742

Keywords: ecology; reptiles; home range; open science; reproducibility; biotelemetry; space use; spatial ecology

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Permalink: https://www.hzdr.de/publications/Publ-33030
Publ.-Id: 33030


Lots of movement, little progress: A review of reptile home range literature

Crane​, M.; Simoes Silva, I. M.; Marshall, B. M.; Strine​, C. T.

Reptiles are the most species-rich terrestrial vertebrate group with a broad diversity of life history traits. Biotelemetry is an essential methodology for studying reptiles as it compensates for several limitations when studying their natural history. We evaluated trends in terrestrial reptile spatial ecology studies focusing upon quantifying home ranges for the past twenty years. We assessed 290 English-language reptile home range studies published from 2000–2019 via a structured literature review investigating publications’ study location, taxonomic group, methodology, reporting, and analytical techniques. Substantial biases remain in both location and taxonomic groups in the literature, with nearly half of all studies (45%) originating from the USA. Snakes were most often studied, and crocodiles were least often studied, while testudines tended to have the greatest within study sample sizes. More than half of all studies lacked critical methodological details, limiting the number of studies for inclusion in future meta-analyses (55% of studies lacked information on individual tracking durations, and 51% lacked sufficient information on the number of times researchers recorded positions). Studies continue to rely on outdated methods to quantify space-use (including Minimum Convex Polygons and Kernel Density Estimators), often failing to report subtleties regarding decisions that have substantial impact on home range area estimates. Moving forward researchers can select a suite of appropriate analytical techniques tailored to their research question (dynamic Brownian Bridge Movement Models for within sample interpolation, and autocorrelated Kernel Density Estimators for beyond sample extrapolation). Only 1.4% of all evaluated studies linked to available and usable telemetry data, further hindering scientific consensus. We ultimately implore herpetologists to adopt transparent reporting practices and make liberal use of open data platforms to maximize progress in the field of reptile spatial ecology.

Keywords: ecology; reptiles; home range; open science; reproducibility; biotelemetry; space use; spatial ecology

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Permalink: https://www.hzdr.de/publications/Publ-33029
Publ.-Id: 33029


Indirect bandgap, optoelectronic properties, and photoelectrochemical characteristics of high-purity Ta₃N₅ photoelectrodes

Eichhorn, J.; Lechner, S. P.; Jiang, C.-M.; Folchi, G.; Munnik, F.; Sharp, I. D.

The (opto)electronic properties of Ta3N5 photoelectrodes are often dominated by defects, such as oxygen impurities, nitrogen vacancies, and reduced tantalum centers, impeding fundamental studies of its electronic structure, chemical stability, and photocarrier transport. Here, we synthesize high quality Ta3N5 thin films by reactive magnetron sputtering and subsequent NH3 annealing at varying temperatures. The resulting films are characterized by nearly-ideal N/Ta stoichiometry, low O content, and small Urbach energies. Both the crystallinity and material quality improve with increasing annealing temperatures up to 940 °C, while higher annealing temperatures introduce additional disorder within the Ta3N5 lattice, leading to reduced photoelectrochemical performance. These changes are also reflected in the surface and bulk composition, showing the elimination of oxygen impurities at moderate annealing temperatures and the loss of nitrogen at high annealing temperatures. As a consequence, defect-related sub-gap optical absorption initially decreases due to reduced oxygen impurity concentration, and subsequently increases due to increased formation of nitrogen vacancies. The high material quality enables us to unambiguously identify the nature of the Ta3N5 band gap as indirect, thereby resolving a long-standing controversy regarding the most fundamental characteristic of this material as a semiconductor. The assignment of Ta3N5 as indirect semiconductor is further supported by the suppression of disorder-induced band-edge photoluminescence with improved structural order within the Ta3N5 films.

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Permalink: https://www.hzdr.de/publications/Publ-33028
Publ.-Id: 33028


Simulating Multi Layer Targets for Grazing Incidence Small Angle X-ray Scattering

Paschke-Brühl, F.-L.

This bachelor thesis studies the feasibility of grazing-incidence small-angle x-ray scattering
(GISAXS) in the UHI laser-target interaction via computational simulations with SMILEI. In
this work we briefly analyze the front and back of the target. We find predominantly that the
compression of the target becomes apparent in the GISAXS pattern, while we can not observe
ablation. We will mainly focus on the density oscillation, a dynamic that has not been mentio-
ned in literature yet. The density oscillation dynamics depend on a simple pressure gradient
in between the layers. We observe the multi layers inversely oscillating in density and a global
density alteration moving through the target. The density alteration allows to recognize the
dynamic in a GISAXS pattern. We learn, that GISAXS is feasible in the high intensity regime,
but not for the same dynamics as in the lower intensity regime.

Keywords: GISAXS; SAXS; grazing-incidence small-angle x-ray scattering; SMILEI; Simulation; Density Oscialltion

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Permalink: https://www.hzdr.de/publications/Publ-33027
Publ.-Id: 33027


Simulating Multi Layer Targets for Grazing Incidence Small Angle X-ray Scattering

Paschke-Brühl, Franziska-Luise

This bachelor thesis studies the feasibility of grazing-incidence small-angle x-ray scattering
(GISAXS) in the UHI laser-target interaction via computational simulations with SMILEI. In
this work we briefly analyze the front and back of the target. We find predominantly that the
compression of the target becomes apparent in the GISAXS pattern, while we can not observe
ablation. We will mainly focus on the density oscillation, a dynamic that has not been mentio-
ned in literature yet. The density oscillation dynamics depend on a simple pressure gradient
in between the layers. We observe the multi layers inversely oscillating in density and a global
density alteration moving through the target. The density alteration allows to recognize the
dynamic in a GISAXS pattern. We learn, that GISAXS is feasible in the high intensity regime,
but not for the same dynamics as in the lower intensity regime.

Keywords: GISAXS; SAXS; grazing incidence small angle x-ray scattering; SMILEI; Simulation; Density Oscillation

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Permalink: https://www.hzdr.de/publications/Publ-33026
Publ.-Id: 33026


Radiation damage evolution in pure W and W-Cr-Hf alloy caused by 5MeV Au ions in a broad range of dpa

Mackova, A.; Havranek, V.; Fernandes, S.; Matejicek, J.; Vilemova, M.; Holy, V.; Liedke, M. O.; Martan, J.; Vronka, M.; Potocek, M.; Babor, P.; Butterling, M.; Elsherif, A. G. A.; Hirschmann, E.; Wagner, A.

Pure W and W-Cr-Hf alloy which are prospective materials for nuclear fusion reactors, such as DEMO,
were irradiated at room temperature with 5 MeV Au2+ ions with fluences between 4 × 1014 and 1.3
× 1016 ions.cm-2 to generate various levels of lattice damage from about units up to tens of dpa. The distinct
character of radiation damage accumulation, microstructure and defect nature have been observed in
both pure W and W-Cr-Hf alloys, the latter exhibited interesting ability of damage reorganisation and
defect size decrease at the higher ion fluences as determined by positron annihilation spectroscopy (PAS),
X-ray diffraction analysis (XRD) identified vertical grain size modification as a function of the Au-ion
fluence. Originally more strained subsurface layer influenced by polishing procedure exhibited the defect
and strain release with the increased Au-ion irradiation fluence in both materials. Radiation damage
saturation has been observed in the deep buried layer at the lower Au-ion fluences in the W-samples
compared to W-Cr-Hf samples; contrary for the higher Au-ion fluence a slight damage decrease was
evidenced in W-Cr-Hf alloys. The distinct defect accumulation was accompanied with the different Au-ion, implanted distribution in the irradiated layer determined by Secondary Ion Mass Spectrometry (SIMS) as
well as the thermal properties have shown the consequent worsening in the depth in good agreement
with the Au-depth concentration profiles. TEM corroborated above mentioned findings, where the subsurface
layer exhibited defect release after the irradiation, the maximum of dislocation loop density has
been identified in the depth according the predicted dpa (displacement particles per atom) maximum for
the lower Au-ion fluences. Moreover, TEM shows the dislocation density band structure appeared in WCr-
Hf samples exhibiting the high density defect band according the projected range of the Au-ions
simultaneously with the additional layer with larger isolated dislocations pronounced in the higher depth
as a growing function of Au-ion ion fluence. Such phenomenon was not observed in W samples.

Keywords: positron annihilation lifetime spectroscopy; SIMS; alloys; W Tungsten

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Permalink: https://www.hzdr.de/publications/Publ-33025
Publ.-Id: 33025


On Inter-bubble Distances and Bubble Clustering in Bubbly Flows: An Experimental Study

Kipping, R.; Wagner, M.; Hampel, U.

Swarm effects in bubble columns result from the interaction of the bubbles at higher gas holdup. The flow around individual bubbles in a swarm influences the movement of the following bubbles and this has a feedback on the flow regime on a larger scale. That is, hydrodynamics that can no longer be described with models for single rising bubbles. The experimental investigation of the multiscale hydrodynamics in three-dimensional bubble columns was so far limited by the available measurement techniques. In this study, ultrafast X-ray tomography (UFXCT) was applied on bubbly flows in a lab scale bubble column to determine inter-bubble distances and clustering characteristics for different gas holdups and bubble diameters. Applying the pair correlation function reveals a pronounced vertical clustering for large bubbles with Eo ≥ 3.82, whereas no clustering has been observed for bubbles of lower Eo. It was found that clustering orientation mainly depends on deformability of the bubbles but not on gas holdup.

Keywords: bubbly flows; ultrafast X-ray tomography; inter-bubble distances; pair correlation function; bubble clustering

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Permalink: https://www.hzdr.de/publications/Publ-33024
Publ.-Id: 33024


NeuLAND: The High-Resolution Neutron Time-of-Flight Spectrometer for R³B at FAIR

Boretzky, K.; Gašparic, I.; Heil, M.; Mayer, J.; Heinz, A.; Caesar, C.; Kresan, D.; Simon, H.; Törnqvist, H. T.; Körper, D.; Alkhazov, G.; Atar, L.; Aumann, T.; Bemmerer, D.; Bondarev, S. V.; Bott, L. T.; Chakraborty, S.; Cherciu, M. I.; Chulkov, L. V.; Ciobanu, M.; Datta, U.; de Filippo, E.; Douma, C. A.; Dreyer, J.; Elekes, Z.; Enders, J.; Galaviz, D.; Geraci, E.; Gnoffo, B.; Göbel, K.; Golovtsov, V. L.; Gonzalez Diaz, D.; Gruzinsky, N.; Haiduc, M.; Heftrich, T.; Heggen, H.; Hehner, J.; Hensel, T.; Hoemann, E.; Holl, M.; Horvat, A.; Horváth, Á.; Ickert, G.; Ignatov, A.; Jelavi Malencia, D.; Johansson, H. T.; Jonson, B.; Kahlbow, J.; Kalantar-Nayestanaki, N.; Kelic-Heil, A.; Kempe, M.; Koch, K.; Kozlenko, N. G.; Krivshich, A. G.; Kurz, N.; Kuznetsov, V.; Langer, C.; Leifels, Y.; Lihtar, I.; Löher, B.; Machado, J.; Martorana, N. S.; Miki, K.; Nilsson, T.; Nyman, G. H.; Orischin, E. M.; Pagano, E. V.; Pirrone, S.; Politi, G.; Potlog, P.-M.; Rahaman, A.; Reifarth, R.; Rigollet, C.; Röder, M.; Rossi, D. M.; Russotto, P.; Savran, D.; Scheit, H.; Schindler, F.; Stach, D.; Stan, E.; Stomvall Gill, J.; Teubig, P.; Trimarchi, M.; Uvarov, L.; Volknandt, M.; Wagner, A.; Wagner, V.; Wranne, S.; Yakorev, D.; Zanetti, L.; Zilges, A.; Zuber, K.

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5x5x250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250x250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.

Keywords: high-energy neutron detection; reactions with relativistic radioactive beams; plastic scintillator scintillator array; multi-neutron detection

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Permalink: https://www.hzdr.de/publications/Publ-33023
Publ.-Id: 33023


Strategic Evaluation of the Traceless Staudinger Ligation for Radiolabeling with the Tricarbonyl Core

Mamat, C.; Jentschel, C.; Köckerling, M.; Steinbach, J.

The traceless Staudinger Ligation with its two variants is a powerful biorthogonal conjugation method not only for the connection of biomolecules, but also for the introduction of fluores-cence or radiolabels under mild reaction conditions. Herein, the strategic evaluation of the traceless Staudinger Ligation for Radiolabeling 99mTc using the [Tc(CO)3] core was presented. A convenient and high-yielding three-step synthesis procedure of dipicolylamine-based phos-phanols as ligands for the mild radiolabeling was developed. The labeling was accomplished using a tricarbonyl kit and 99mTc-pertechnetate generator eluate showing 87% radiochemical conversion. The respective rhenium-based, non-radioactive reference compounds were synthe-sized using (Et4N)2[Re(CO)3Br3] as precursor. All products were analyzed by NMR, MS and ele-mental analysis. Additional XRD analyses were performed.

Permalink: https://www.hzdr.de/publications/Publ-33021
Publ.-Id: 33021


Stability analysis of discrete population balance model for bubble growth and shrinkage

Li, J.; Liao, Y.; Lucas, D.; Zhou, P.

The stability condition for solving the population balance equation (PBE) involving bubble growth and shrinkage within the Eulerian framework is proposed. The particle flux weighted average Courant number, CCFL, which reflects the propagation of particle state of the entire size classes on internal coordinates is first derived. Stability conditions of internal convection for PISO and PIMPLE algorithms are obtained by evaluating a series of tests concerning the constant bubble growth. The proposed stability conditions are then applied to simulate two kinds of laboratory experiments, i.e. the bubble growth in stagnant liquid and condensing steam-water pipe flows. The results show that the stable PBE solutions hold for the cases using either PISO or PIMPLE algorithms combined with the corresponding stability condition. Meanwhile, the conservation of the zeroth and first moments of the number density function can be guaranteed when the stability condition is satisfied. In addition, the effect of heat transfer coefficient correlations is also discussed.

Keywords: Stability analysis; Internal CFL condition; Discretization; Population balance equation; Class method; Phase change

Permalink: https://www.hzdr.de/publications/Publ-33020
Publ.-Id: 33020


Acoustically induced coherent spin trapping

Hernandez-Minguez, A.; Poshakinskiy, A. V.; Hollenbach, M.; Santos, P. V.; Astakhov, G.

Hybrid spin-optomechanical quantum systems offer high flexibility, integrability and applicability for quantum science and technology. Particularly, on-chip surface acoustic waves (SAWs) can efficiently drive spin transitions in the ground states (GSs) of atomic-scale, color centre qubits, which are forbidden in case of the more frequently used electromagnetic fields. Here, we demonstrate that strain-induced spin interactions within their optically excited state (ES) can exceed by two orders of magnitude the ones within the GS. This gives rise to novel physical phenomena, such as the acoustically induced coherent spin trapping (CST) unvealed here. The CST manifests itself as the spin preservation along one particular direction under the coherent drive of the GS and ES by the same acoustic field. Our findings provide new opportunities for the coherent control of spin qubits with dynamically generated strain fields that can lead towards the realization of future spin-acoustic quantum devices.

Keywords: Spin qubits; surface acoustic waves; quantum technology; SiC

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Permalink: https://www.hzdr.de/publications/Publ-33018
Publ.-Id: 33018


Laser-induced ionization of ions from liquid alloy ion sources of high brightness

Machalett, F.; Ying, B.; Wustelt, P.; Huth, V.; Kübel, M.; Bischoff, L.; Klingner, N.; Pilz, W.; Stöhlker, T.; Paulus, G. G.

In this work, we have generated ion beam targets of metal and metalloid ions using a high-brightness liquid metal ion source (LMIS) originally applied in focused ion beam systems. Using an eutectic Au-Si alloy as a low melting point source feed material, ions of different ion species were detected: Si^{2+}, Si^+, Au^{2+}, Au^+, Au^{2+}, Au^{3+} and Au^{32+}. The source current between emitter needle and extractor electrode is in the range of 10 - 60 μA and can be adjusted up to about 150 μA. The ion source is characterized by high ion current stability and a suitable emission lifetime of several days, which is limited by the amount of material and can be further increased.
To study the strong-field laser ionization, we used a E x B filter and selected Si^{2+} and Au+ ions as ionic targets, because of their high beam intensity. We investigated ultrafast laser-induced ionization, which leads to higher charge states after multiple ionization of both ion species. Laser intensities of up to 10^{16} W/cm^2 allow observation of up to 10-fold ionization of Au^+ ions and 3-fold ionization of Si^{2+} ions.
The aim of further work is to extend the available ion beam targets to other elements of the periodic table to study ultrafast laser-induced fragmentation and ionization dynamics of atoms and molecules in strong laser fields. Another goal is the further increase of the density of ion laser targets for more reliable statistics and shorter measurement times. Further steps are technical improvements of ion source and ion optics as well as the investigation of heavy metal dimers such as Au^{2+}.

Keywords: liquid metal ion source; laser intensity; ultrafast laser-induced fragmentation; ionization dynamics

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  • Lecture (Conference) (Online presentation)
    18th SPARC Topical Workshop, 06.-09.09.2021, Darmstadt, Germany

Permalink: https://www.hzdr.de/publications/Publ-33017
Publ.-Id: 33017


Laser-induced ionization of ions from high brightness ion sources

Machalett, F.; Ying, B.; Wustelt, P.; Huth, V.; Kübel, M.; Bischoff, L.; Klingner, N.; Pilz, W.; Stöhlker, T.; Paulus, G. G.

Au and Si ions from high brightness liquid metal ion sources (LMIS) are used as ionic targets for strong-field laser interaction with femtosecond laser beam. Field ionization processes in the field emission source at electrostatic fields of some 10 V/nm allow the generation of various metallic and metalloid ion beams with charge states such as Au^{2+} and Si^{2+}. Studying the ionization in strong femtosecond laser fields with intensities of up to 1E16 W/cm^2, we observed for these elements charge states up to Au^{11+} and Si^{4+}.

Keywords: liquid metal ion sources; femtosecond laser beam; charge states

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  • Lecture (Conference) (Online presentation)
    32nd International Conference on Photonic, Electronic and Atomic Collisions, ViCPEAC2021, 20.-23.07.2021, European XFEL, Germany

Permalink: https://www.hzdr.de/publications/Publ-33016
Publ.-Id: 33016


Experimental and numerical investigations of Ni–Co–SiO2 alloy films deposited by magnetic-field-assisted jet plating

Jiang, W.; Huang, M.; Lao, Y.; Yang, X.; Wang, C.; Tian, Z.; Zhou, S.; Mutschke, G.; Eckert, K.

A new method of magnetic-field-assisted jet plating is presented to manufacture Ni-Co-SiO2 alloy films. The influence of different concentrations of Co2+ ions of the electrolyte is investigated with and without magnetic field to study the resulting properties of the deposits. The texture orientation, surface morphology, magnetic properties and corrosion resistance of the alloy films were characterized. The results show that with increasing Co2+ concentration in conventional jet-plating, the surface morphology changes from a granular crystal structure to a needle-like structure at 30 g/L caused by the hexagonal close-packed (HCP) structure of a large Co content. Differently, the assistance of the magnetic field leads to lower Co content in the films, even at a high Co2+ concentration of 30 g/L. The deposit layer remains in the face-centered cubic (FCC) structure and shows a granular morphology. The magnetic field in general leads to grain refinement and inhibits the abnormal Ni–Co co-deposition. The Ni–Co–SiO2 alloy films obtained by magnetic-field-assisted jet plating have a smooth and dense surface. The best soft magnetic properties and corrosion resistance are obtained at a Co2+ concentration of 20 g/L. The coercivity is as low as 7.5 Oe, and the corrosion current density is as low as 1.12 μA·cm-2 in 3.5 wt% NaCl solution without agitation and at room temperature, clearly showing the advantages of the method for preparing superior soft magnetic materials. In addition, a physical model of magnetic-field-assisted jet plating is established. The magnetic forces and the resulting electrolyte flow are analyzed with the help of numerical simulations, and the influence of the magnetic field on the deposition process is discussed from the perspective of magnetohydrodynamics.

Keywords: Ni–Co–SiO2 alloy film; Magnetic-field-assisted jet plating; Magnetic properties; Numerical simulation

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Permalink: https://www.hzdr.de/publications/Publ-33014
Publ.-Id: 33014


Increased dephasing length in heavily doped GaAs

Duan, J.; Wang, C.; Vines, L.; Rebohle, L.; Helm, M.; Zeng, Y.-J.; Zhou, S.; Prucnal, S.

Ion implantation of S and Te followed by sub-second flash lamp annealing with peak temperature about 1100 oC is employed to obtain metallic n++-GaAs layers. The electron concentration in annealed GaAs is as high as 5×1019 cm-3, which is several times higher than the doping level achievable by alternative methods. We found that heavily doped n++-GaAs exhibits positive magnetoconductance in the temperature range of 3-80 K, which is attributed to the magnetic field suppressed weak localization. By fitting the magnetoconductance results with Hikami-Larkin-Nagaoka model, it is found that the phase coherence length increases with increasing carrier concentration at low temperature and is as large as 540 nm at 3 K. The temperature dependence of the phase coherence length follows〖 l〗_∅∝T^η (η~0.3), indicating defect-related scattering as the dominant dephasing mechanism. In addition, the high doping level in n-type GaAs provides the possibility to use GaAs as a plasmonic material for chemical sensors operating in the infrared range.

Keywords: ion implantation; heavily doped GaAs; phase coherence length; sub-second annealing; plasmonic

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Permalink: https://www.hzdr.de/publications/Publ-33012
Publ.-Id: 33012


Software publication: Automated coordination corrected enthalpies with AFLOW-CCE

Friedrich, R.; Esters, M.; Oses, C.; Ki, S.; Brenner, M. J.; Hicks, D.; Mehl, M. J.; Toher, C.; Curtarolo, S.

The implementation of the coordination corrected enthalpies (CCE) method is available via the AFLOW software for materials discovery as the AFLOW-CCE module.

Keywords: materials themrodynamics; enthalpy correction; materials design

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  • Software in external data repository
    Publication year 2021
    Programming language: C++
    System requirements: Unix
    License: GNU General Public License version 3
    Hosted on AFLOW: Link to location

Permalink: https://www.hzdr.de/publications/Publ-33011
Publ.-Id: 33011


Supplementary material: Ph.D. dissertation of Lucas Pereira, TU Bergakademie Freiberg, 2021.

Pereira, L.
Supervisor: Frenzel, Max; Supervisor: Tolosana-Delgado, Raimon; Supervisor: Gutzmer, Jens

This supplementary material supports the Ph.D. dissertation of Lucas Pereira, submitted to the Faculty 3 of the TU Bergakademie Freiberg.

C2.SM1.Percentiles.xlsx: Mentioned in the chapter 2 of the dissertation, this file contains, in terms of percentiles, the distribution of every particle descriptive variable in the different samples used to train the logistic regression models of the case study presented in this chapter.

C2.SM2.Coefficients.xlsx: Mentioned in the chapter 2 of the dissertation, this file contains the complete list of coefficients assigned to each variable, in each separation unit, of the case study presented in this chapter.

C4.SM1.StatWeight.xlsx: Mentioned in the chapter 4 of the dissertation, this file contains a detailed explanation of the statistical weights of particles and how they can be used to integrate a set of particle datasets from different streams and size fractions into a single and balanced training dataset.

Keywords: Geometallurgy; Particle-based separation model

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Permalink: https://www.hzdr.de/publications/Publ-33009
Publ.-Id: 33009


How 5f electron polarizability drives covalency and selectivity in actinide N-donor complexes

Köhler, L.; Patzschke, M.; Schmidt, M.; Stumpf, T.; März, J.

We report a series of isostructural tetravalent actinide (Th, U-Pu) complexes with the N-donor ligand N,N'-ethylene-bis((pyrrole-2-yl)methanimine) (H₂ L, H₂ pyren). Structural data from SC-XRD analysis reveal [An(pyren)₂ ] complexes with different An–N(imine) vs. An–N(pyrrolide) bond lengths, respectively. Quantum chemical calculations elucidate the bonding situation, including differences in covalent character of the coordinative bonds. A comparison to the intensely studied analogous N,N′‐ethylene‐bis(salicylideneimine) (H₂ salen) based complexes [An(salen)₂ ] displays on average almost equal electron sharing of pyren or salen with the An(IV), pointing to a potential ligand-cage-driven complex stabilization. This is shown in the fixed ligand arrangement of pyren and salen in the respective An(IV) complexes. The overall bond strength of the pure N-donor ligand pyren to An(IV) (An=Th, U, Np, Pu) is slightly weaker compared to salen, with the exception of the Pa(IV) complex, which exhibits extraordinarily high electron sharing of pyren with Pa(IV). Such an altered ligand preference within the early An(IV) series points to a specificity of the 5f¹ configuration, which can be explained by polarization effects of the 5f electrons, allowing strongest f electron backbonding from Pa(IV) (5f¹ ) to the N-donors of pyren.

Keywords: actinides; N donor ligands; bonding analysis; f electrons; pyrrole

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Permalink: https://www.hzdr.de/publications/Publ-33008
Publ.-Id: 33008


On the nature of Pb species in Pb-(over)exchanged zeolite: a combined experimental and theoretical study

Roos, D. P.; Scheinost, A.; Churakov, S. V.; Nagashima, M.; Cametti, G.

Structural properties of Pb-exchanged zeolites are of interest because of their applications in environmental remediation and in industrial processes. In this study, we report on a Pb-exchanged aluminosilicate zeolite (Pb-STI), with particular focus on the cationic species, which form inside the zeolitic pores as a result of the exchange experiments. The produced
zeolite had chemical composition Pb13.4(OH)10Al17.4Si54.6O144 ∙38H2O, indicating a Pb2+ overexchange of approximately 50%. The STI framework maintained the Fmmm space group characteristic of the type material. However, the extraframework occupants, Pb2+, H2O and OH-, were characterized by a strong positional-disorder. The latter was resolved and
interpreted combining Extended X-ray Absorption Fine Structure (EXAFS) analysis with Molecular Dynamics (MD) simulations. On average, Pb2+ ions are coordinated by 2 OH- and
1 H2O at distances < 2.5 Å, whereas bonds to framework oxygen-atoms were found only at longer distances (> 2.8 Å). Pb2+ adopts mainly a sided distorted coordination, indicating a
stereochemical activity of the lone pair electrons. The obtained results were compared with those of other mono-cationic forms of STI zeolites. Based on the analysis of the framework
distortion experienced after the incorporation of different metal ions, considerations are drawn on the potential effect of Pb2+ on the thermal stability of STI framework type zeolites.

Keywords: XAFS; Zeolite; XRD; Molecular dynamics; DFT

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Permalink: https://www.hzdr.de/publications/Publ-33007
Publ.-Id: 33007


Automated coordination corrected enthalpies with AFLOW-CCE

Friedrich, R.; Esters, M.; Oses, C.; Ki, S.; Brenner, M. J.; Hicks, D.; Mehl, M. J.; Toher, C.; Curtarolo, S.

The computational design of materials with ionic bonds poses a critical challenge to thermodynamic modeling
since density functional theory yields inaccurate predictions of their formation enthalpies. Progress requires
leveraging physically insightful correction methods. The recently introduced coordination corrected enthalpies
(CCE) method delivers accurate formation enthalpies with mean absolute errors close to room temperature
thermal energy, i.e., ≈25 meV/atom. The CCE scheme, depending on the number of cation-anion bonds and
oxidation state of the cation, requires an automated analysis of the system to determine and apply the correction.
Here, we present AFLOW-CCE—our implementation of CCE into the AFLOW framework for computational
materials design. It features a command line tool, a web interface, and a Python environment. The workflow
includes a structural analysis, automatically determines oxidation numbers, and accounts for temperature effects
by parametrizing vibrational contributions to the formation enthalpy per bond.

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Permalink: https://www.hzdr.de/publications/Publ-33006
Publ.-Id: 33006


Compact spectroscopy of keV to MeV X-rays from a laser wakefield accelerator

Hannasch, A.; Laso García, A.; La Berge, M.; Zgadzaj, R.; Köhler, A.; Couperus Cabadağ, J. P.; Zarini, O.; Kurz, T.; Ferrari, A.; Molodtsova, M.; Naumann, L.; Cowan, T.; Schramm, U.; Irman, A.; Downer, M.

We reconstruct spectra of secondary X‑rays from a tunable 250–350 MeV laser wakefield electron accelerator from single‑shot X‑ray depth‑energy measurements in a compact (7.5 × 7.5 × 15 cm), modular X‑ray calorimeter made of alternating layers of absorbing materials and imaging plates. X‑rays range from few‑keV betatron to few‑MeV inverse Compton to > 100 MeV bremsstrahlung emission, and are characterized both individually and in mixtures. Geant4 simulations of energy deposition of single‑energy X‑rays in the stack generate an energy‑vs‑depth response matrix for a given stack configuration. An iterative reconstruction algorithm based on analytic models of betatron, inverse Compton and bremsstrahlung photon energy distributions then unfolds X‑ray spectra,
typically within a minute. We discuss uncertainties, limitations and extensions of both measurement and reconstruction methods.

Permalink: https://www.hzdr.de/publications/Publ-33005
Publ.-Id: 33005


Data publication: Broadband frequency filters with quantum dot chains

Ehrlich, T.; Schaller, G.

Rohdaten für Abbildungen (*.agr) und Mathematica Notebooks (*.nb) für die Berechnungen

Keywords: thermodynamic uncertainty relation; Levitov-Lesovik formula; transmission; reaction-coordinate mapping

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Permalink: https://www.hzdr.de/publications/Publ-33004
Publ.-Id: 33004


Automated mineralogy particle dataset: dry magnetic separation of skarn ore

Buchmann, M.; Kern, M.; Pereira, L.; Frenzel, M.; Tolosana Delgado, R.; van den Boogaart, K. G.; Gutzmer, J.

This data set origins from the AFK (“Aufbereitung feinkörniger Komplexerze”, BMBF grant number 033R128) project. The main target within this project was to produce a cassiterite concentrate, which is suitable for the subsequent production of tin. Various processing steps and the material specific behaviour were investigated within the progress of the project. The present data set derives from dry magnetic separation tests. More information can be found in the "readme.pdf" file attached.

Keywords: Geometallurgy; Particle-based separation modelling; Magnetic separation; Cassiterite

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Permalink: https://www.hzdr.de/publications/Publ-33003
Publ.-Id: 33003


Data publication: Microscopic and spectroscopic bioassociation study of uranium(VI) with an archaeal Halobacterium isolate

Hilpmann, S.; Bader, M.; Steudtner, R.; Müller, K.; Stumpf, T.; Cherkouk, A.

Bei diesem Datensatz handelt es sich um die Primärdaten der Untersuchung der Wechselwirkungen eines halophilen Archaeons mit Uran(VI). Dazu wurden Konzentrationsbestimmungen mittels ICP-MS durchgeführt, Lumineszenzspektren mittels zeitaufgelöster laserinduzierter Lumineszenzspektroskopie und IR Spektren aufgenommen. Darüber hinaus wurden Bilder der Zellen mit Hilfe der Fluoreszenzmikroskopie aufgenommen.

Keywords: uranium(VI) bioassociation; halophilic archaea; rock salt

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Permalink: https://www.hzdr.de/publications/Publ-33002
Publ.-Id: 33002


Monte Carlo methods in particle and nuclear physics

Müller, S.

Presentation at HZDR's 2021 summer student seminar

Keywords: Monte Carlo; Simulation

  • Lecture (Conference) (Online presentation)
    Summer Student seminar series, 27.07.2021, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-33001
Publ.-Id: 33001


Microscopic and spectroscopic bioassociation study of uranium(VI) with an archaeal Halobacterium isolate

Hilpmann, S.; Bader, M.; Steudtner, R.; Müller, K.; Stumpf, T.; Cherkouk, A.

The safe disposal of high-level radioactive waste in a deep geological repository is a huge social and scientific issue. So far, one of the less considered factors, especially in terms of a long-term risk assessment, is the impact of microorganisms occurring in the different host rocks. Even under the harsh conditions of salt formations different bacterial and archaeal species were found, e. g. Halobacterium sp. GP5 1-1, which has been isolated from a German rock salt sample. The interactions of this archaeon with uranium(VI), one of the major radionuclides of concern for the long-term storage of high-level radioactive waste, were investigated. Different spectroscopic techniques, as well as microscopy, were used to examine the occurring mechanisms on a molecular level leading to a more profound process understanding. Batch experiments with different uranium(VI) concentrations showed that the interaction is not only a simple, but a more complex combination of different processes. With the help of in situ attenuated total reflection Fourier-transform infrared spectroscopic investigations the association of uranium(VI) onto carboxylate groups was verified. In addition, time-resolved laser-induced luminescence spectroscopic investigations revealed the formation of a phosphate and carboxylate species within the cell pellets in dependence on the uranium(VI) concentration and the incubation time. Furthermore, the association behavior differs from another very closely related halophilic archaeon, especially with regard to uranium(VI) concentrations. This clearly demonstrates the importance of studying the interactions of different, at first sight very similar, microorganisms with uranium(VI). Overall, the findings presented in this work provide new insights into the microbe-uranium(VI) interactions at highly saline conditions relevant to the long-term storage of radioactive waste in rock salt.

Keywords: uranium(VI) bioassociation; halophilic archaea; rock salt

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Permalink: https://www.hzdr.de/publications/Publ-33000
Publ.-Id: 33000


FPGA-based Real-Time Data Acquisition for Ultrafast X-Ray Computed Tomography

Windisch, D.; Knodel, O.; Juckeland, G.; Hampel, U.; Bieberle, A.

Ultrafast X-ray computed tomography (UFXCT) is a fast tomographic imaging technique based on the principle of electron beam scanning. It is used for the investigation of transient multiphase flows. A UFXCT scanner comprises of multiple detector modules generating gigabytes of raw data per second for imaging rates of up to 8,000 frames per second. During the data acquisition, this data is stored in RAM on each detector module and can therefore only be accessed after the acquisition. This limits applicability of UFXCT systems because real-time control of the scanned process or the scanner itself is not possible. Using the newly developed FPGA-based data acquisition described in this paper, the data acquisition is enhanced to real-time operation, i.e., streaming the acquired data to the processing computer within microseconds of their acquisition. The developed FPGA firmware handles control of peripherals (such as analog-digital converters), synchronization between detector modules, electron beam deflection, and data transfer via gigabit ethernet.

Keywords: Computed tomography; Data acquisition; Field programmable gate arrays

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Permalink: https://www.hzdr.de/publications/Publ-32999
Publ.-Id: 32999


P2001 - Vorrichtung zur gezielten Anordnung von in einem Analyten gelösten, elektrisch polarisierbaren Materialien, Verfahren zur Bestimmung eines isoelektrischen Punktes eines elektrisch isolierenden Materials, Verfahren zum gezielten Anordnen eines in einem Analyten gelösten elektrisch polarisierbaren Materials

Rebohle, L.; Fischer, C.; Skorupa, I.; Schmidt, H.; Krüger, S.; Blaschke, D.

Es wird eine Vorrichtung (10) zur gezielten Anordnung eines in einem Analyten gelösten, elektrisch polarisierbaren Materials (4), aufweisend eine siliziumhaltige Trägerstruktur (3), eine elektrisch isolierende erste Deckstruktur (1) mit einem ersten isoelektrischen Punkt und eine elektrisch isolierende zweite Deckstruktur (2) mit einem zweiten isoelektrischen Punkt vorgeschlagen, wobei der erste isoelektrische Punkt vom zweiten isoelektrischen Punkt verschieden ist. Weiterhin werden ein Verfahren zur Bestimmung eines ersten isoelektrischen Punktes eines Materials sowie ein Verfahren zum gezielten Anordnen eines in einem Analyten gelösten, elektrisch polarisierbaren Materials (4) vorgeschlagen.

  • Patent
    DE102020200470 - Erteilung 20.05.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32998
Publ.-Id: 32998


P1916 - Verfahren und Anordnung zum Charakterisieren der Positionierung eines Objekts

Hampel, U.

Die Erfindung betrifft ein Verfahren und eine Anordnung zum Charakterisieren der Positionierung eines Objekts innerhalb eines Aufenthaltsbereichs, wobei mittels eines Myonenteleskops darauf auftreffende Myonen als Myonenteleskop-Detektionsereignisse und deren Myonentrajektorien als Myonentrajektorien-Daten erfasst werden, wobei zudem mittels eines objektseitigen Myonendetektors darauf auftreffende Myonen als Myonendetektor-Detektionsereignisse erfasst werden, und wobei quasizeitgleiche Myonenteleskop-Detektionsereignisse und Myonendetektor-Detektionsereignisse ermittelt werden und basierend auf den zugehörigen Myonentrajektorien-Daten die Positionierung des Objekts charakterisiert wird.

  • Patent
    DE102019131006 - Erteilung 01.10.2020

Permalink: https://www.hzdr.de/publications/Publ-32997
Publ.-Id: 32997


P1915 - Magnetische Streufeld-Struktur, magnonisches Bauelement und Verfahren zur Herstellung einer magnetischen Streufeldstruktur

Samad, F.; Koch, L.; Arekapudi, S. S. P. K.; Hellwig, O.; Schultheiß, H.

Eine magnetische Struktur (510) weist einen synthetischen antiferromagnetischen Schichtstapel (100) mit senkrechter magnetischer Anisotropie auf. Ein erster und ein zweiter Teilbereich (110, 120) des synthetischen antiferromagnetischen Schichtstapels (100) sind lateral nebeneinander ausgebildet. Eine vertikaler erster Magnetisierungsverlauf im ersten Teilbereich (110) unterscheidet sich nach Betrag und/oder Orientierung von einem vertikalen zweiten Magnetisierungsverlauf im zweiten Teilbereich (120). Auf einer horizontalen Hauptoberfläche (101) des synthetischen antiferromagnetischen Schichtstapels (100) kann eine Entkopplungsschicht (200) ausgebildet sein. Auf der Entkopplungsschicht (200) oder der Hauptoberfläche (101) ist eine Funktionsschicht (300) ausgebildet. Die Funktionsschicht (300) wird lokal durch Kopplung mit dem synthetischen antiferromagnetischen Schichtstapel (100)oder durch die Streufelder des synthetischen antiferromagnetischen Schichtstapels (100)in ihrer Magnetisierung ausgerichtet, wodurch in der Funktionsschicht (300) beispielsweise eine variable und reprogrammierbare Infrastruktur für die Erzeugung, Verarbeitung, Übertragung und Detektion von Spinwellen erzeugt werden kann.

  • Patent
    DE102019129203 - Offenlegung 29.04.2021

Permalink: https://www.hzdr.de/publications/Publ-32996
Publ.-Id: 32996


P1909 - Mehrphasen-Messsystem mit Kalibrierwertnachführung und strömungstechnische Anordnung

Wiedemann, P.; Flaisz, A.; Schleicher, E.

Ein Mehrphasen-Messsystem (100) für ein mehrphasiges Fluid (205) weist eine Referenzwert-Messanordnung (160) und eine Mehrphasen-Messeinrichtung (130) auf. Die Referenzwert-Messanordnung (160) weist mindestens eine Kapillare (110) und eine Kapillaren- Messeinrichtung (120) auf. Innere Querschnittsfläche und Länge der Kapillare (110) sind so bemessen, dass bei Durchströmung der Kapillare (110) Phasen des mehrphasigen Fluids (205) in Durchströmungsrichtung separieren. Die Kapillaren-Messeinrichtung (120) ist zur Bestimmung mindestens einer physikalischen Eigenschaft mindestens einer der durch die Kapillare (110) fließenden Phasen eingerichtet. Das Mehrphasen-Messeinrichtung (130) ist für eine Messung
eines Volumen- und/oder Massenanteils von mindestens einer Phase des mehrphasigen Fluids und/oder für eine Messung eines Volumen- und/oder Massenstromes von mindestens einer der Phasen des mehrphasigen Fluids unter Berücksichtigung der durch die Kapillaren-Messeinrichtung (120) bestimmten physikalischen Eigenschaft(en) eingerichtet.

  • Patent
    DE102019125243 - Offenlegung 25.03.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32995
Publ.-Id: 32995


P1908 - Verfahren zum Herstellen eines gedruckten magnetischen Funktionselements und gedrucktes magnetisches Funktionselement

Canon Bermudez, G. S.; Mönch, J. I.; Makarov, D.

Die vorliegende Erfindung betrifft ein Verfahren zum Herstellen eines gedruckten magnetischen Funktionselements, bei dem ein Substrat (1) auf einer Oberfläche mit mindestens einem Kontakt (2) aus einem elektrisch leitfähigen Werkstoff versehen wird. Nachfolgend wird auf den oder an den mindestens einen Kontakt (2) und diesen unmittelbar berührend eine Struktur (3) aus einem einen magnetoresistiven Effekt aufweisenden Werkstoff als Paste, als Gel, als Dispersion oder als Suspension aufgedruckt sowie die Struktur (3) durch eine Bestrahlung mit elektromagnetischer Strahlung über einen Zeitraum im Millisekundenbereich elektrisch leitfähig und magnetfeldempfindlich.

  • Patent
    DE102019211970 - Offenlegung 11.02.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32994
Publ.-Id: 32994


P1907 - Deuterierte 7-(3-(4-(2-([18F]Fluor)ethoxy)phenyl)propyl)-2-(furan-2-yl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amin-Derivate

Lai, T. H.; Teodoro, R.; Toussaint, M.; Gündel, D.; Deuther-Conrad, W.; Dukic-Stefanovic, S.; Schröder, S.; Moldovan, R.-P.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I worin die Reste X1a, X1b, X2a, X2b, X3a, X3b, X4a, X4b, X5a und X5b unabhängig voneinander jeweils Wasserstoff oder Deuterium sind, mit der Maßgabe, dass zumindest einer der Reste X1a, X1b, X2a, X2b, X3a, X3b, X4a, X4b, X5a und X5b Deuterium ist.

  • Patent
    DE102019116986 - Offenlegung 24.12.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32993
Publ.-Id: 32993


P1906 - 3-(4-Amino-2-methoxyphenyl)-2-cyanoacrylsäure-Derivate und deren Verwendung als Präkursoren für die Herstellung radiochemischer Verbindungen

Moldovan, R.-P.; Sadeghzadeh, M.; Wenzel, B.; Kranz, M.; Teodoro, R.; Ludwig, F.-A.; Fischer, S.; Toussaint, M.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel (E)-I oder (Z)-I worin Y eine Hydroxygruppe oder eine O-M+-Gruppe ist, wobei M+ ein Kation ist; Z1 aus der Gruppe ausgewählt ist, die aus einer substituierten oder unsubstituierten C1-C12-Alkylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkenylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkinylgruppe, einer substituierten oder unsubstituierten Arylgruppe, einer substituierten oder unsubstituierten Heteroarylgruppe, einer substituierten oder unsubstituierten Alkylarylgruppe, einer substituierten oder unsubstituierten Arylalkylgruppe und einer Gruppe -A1-X besteht, worin A1 eine Kohlenwasserstoffkette mit ein bis vier substituierten oder unsubstituierten Methylengruppen ist, wobei in der Kohlenwasserstoffkette zumindest ein Sauerstoffatom unter Ausbildung einer Ethergruppe angeordnet sein kann, und X aus der Gruppe ausgewählt ist, die aus einer Methylgruppe, einem Halogen und einer Hydroxygruppe besteht; und Z2 ein Rest ist, der eine Abgangsgruppe AG trägt, wobei Z2 aus der Gruppe ausgewählt ist, die aus einer substituierten oder unsubstituierten C1-C12-Alkylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkenylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkinylgruppe, einer substituierten oder unsubstituierten Arylgruppe, einer substituierten oder unsubstituierten Heteroarylgruppe, einer substituierten oder unsubstituierten Alkylarylgruppe und einer substituierten...

  • Patent
    DE102019112040 - Offenlegung 12.11.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32992
Publ.-Id: 32992


P1905 - N-(4-methoxy-7-morpholinobenzo[d]thiazol-2-yl)-acetamid-Derivate und deren Verwendung

Lai, T. H.; Teodoro, R.; Moldovan, R.-P.; Kranz, M.; Dukic-Stefanovic, S.; Toussaint, M.; Spalholz, T.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I (Formel I)
worin Ar eine Phenylgruppe oder eine Pyridylgruppe ist; R1 Wasserstoff oder eine Nitrogruppe ist; und R2 Fluor oder eine Abgangsgruppe ist, wobei die Abgangsgruppe aus der Gruppe ausgewählt ist, die aus einer Nitrogruppe, einem Halogen, einem Diazoniumion oder -salz, einem Trialkylammoniumion oder -salz, einem Dialkoxyaren, einem Sulfoxid, einer Boronsäure, einem Boronsäureester, Alkylzinn, Arylzinn, einem Iodoniumion oder -salz, einem Iodonium-Ylid und einem Sulfonsäureester besteht.

  • Patent
    DE102019110904 - Offenlegung 29.10.2020

Permalink: https://www.hzdr.de/publications/Publ-32991
Publ.-Id: 32991


P1904 - Verwendung eines Komplexierungsmittels zur Rückgewinnung von Metallionen aus Industrieabwasser sowie ein Verfahren dazu

Jain, R.; Joshi, T.; Pollmann, K.

Die vorliegende Erfindung betrifft ein neues Komplexierungsmittel zur Rückgewinnung von Metallionen aus Industrieabwasser, aufweisend ein Trägermaterial, an dem Siderophore über einen Linker kovalent immobilisiert sind, wobei der Linker eine Polyethylenglykol-Kette enthält, und wobei der Linker eine Masse von 2000-3500 Da aufweist, sowie ein Verfahren zu dessen Herstellung und die Verwendung des Komplexierungsmittels bei der Rückgewinnung von Metallen aus Industrieabwässern.

  • Patent
    DE102019108803 - Offenlegung 08.10.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32990
Publ.-Id: 32990


P1903 - Anordnung zur berührungslosen Bestimmung der Geschwindigkeitsverteilung eines Schmelzvolumens in einer Stranggusskokille

Ratajczak, M.; Wondrak, T.; Stefani, F.; Primetals Austria

Die Erfindung betrifft eine Anordnung zur berührungslosen Bestimmung einer Geschwindigkeitsverteilung eines Schmelzvolumens in einer Stranggusskokille. Die erfindungsgemäße Anordnung soll eine Messung mit verbesserten Signal-Rausch-Verhältnis ermöglichen und in bestehende Bauteile integriert werden. Die Anordnung weist mindestens eine ein primäres Magnetfeld erzeugende Spule, deren primäres Magnetfeld das Schmelzvolumen durchdringt, und eine Mehrzahl von Magnetfeldsensoren zur Messung des durch die Wechselwirkung der Schmelzbewegung mit dem erzeugten primären Magnetfeld induzierten Magnetfeldes auf. Die Stranggusskokille weist mindestens ein Kokillenelement auf, welches in mindestens einem Bereich mit einem Anschlusselement verbunden ist. Spule und Magnetfeldsensoren sind derart innerhalb des Anschlusselements angeordnet, dass die Magnetfeldsensoren innerhalb des von der Spule umschlossenen Volumens des Anschlusselements angeordnet sind.

  • Patent
    DE102019105628 - Erteilung 19.03.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32989
Publ.-Id: 32989


Data publication: Stretchable Thin Film Mechanical Strain Gated Switches and Logic Gate Functions Based on a Soft Tunneling Barrier

Chae, S.; Jin Choi, W.; Fotev, I.; Bittrich, E.; Uhlmann, P.; Schubert, M.; Makarov, D.; Wagner, J.; Pashkin, O.; Fery, A.

Time-domain THz spectroscopy (raw data) and the analysis of the delay time (Origin file)

Keywords: Strain gated electric switch; logic gates; tunneling; stretchable circuit; thin film

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Permalink: https://www.hzdr.de/publications/Publ-32988
Publ.-Id: 32988


Magnetostructural Phase Transition in Fe₆₀V₄₀ Alloy Thin Films

Anwar, M. S.; Cansever, H.; Böhm, B.; Gallardo, R.; Hübner, R.; Kentsch, U.; Zhou, S.; Eggert, B.; Wende, H.; Potzger, K.; Faßbender, J.; Lenz, K.; Lindner, J.; Hellwig, O.; Bali, R.

The tuning and control over the intrinsic magnetic properties, such as saturation magnetization (Ms) and Gilbert damping (α), can be obtained via systematic rearrangement of the lattice at the nanoscale. In certain binary alloys such as B2 Fe60Al40 [1] and B2 Fe50Rh50 [2], the Ms can be tuned by inducing chemical disorder. The disorder caused by the randomization of site occupancies of the atoms can be achieved by ion-irradiation. Here we explore a magnetic phase transition in Fe60V40 thin films caused by ordering of the lattice structure from short-range order to the crystalline state.
Fe60V40 films (~ 40 nm) were grown onto SiO2/Si substrate. The as-grown films are weakly ferromagnetic with low Ms of 17 kA/m; whereas irradiation with 25 keV Ne+-ions at fluences of ~ 5 × 1015 ions/cm2 leads to a drastic increase of Ms to ~ 750 kA/m, as shown in Fig. 1. X-ray diffraction as well as transmission electron microscopy reveal a structural short-range order in the as-grown films, that transform to A2 Fe60V40 with increasing Ne+-fluence. The A2 region appears to nucleate at the film top surface and with increasing fluence, it propagates deeper down into the film. The effect of the phase transition on the dynamic behaviour has been investigated using ferromagnetic resonance (Fig. 2). The low value of Gilbert damping (~ 0.002) has been obtained from the frequency dependence of the resonance spectra. Furthermore, the transition can be tracked using Conversion electron Mössbauer spectroscopy to shed light on the variation of local magnetic ordering during the transition. The tunable film structure as well as low damping form the basis for further investigations on nanomagnets embedded within Fe60V40 thin films.

Funding by the DFG - 322462997 (BA 5656/1-2 | WE 2623/14-2) is acknowledged. Ion-irradiation was performed at the Ion Beam Centre of the HZDR.

References
[1] J. Ehrler, et al., New J. Phys., 22, 073004 (2020).
[2] B. Eggert, et al., RSC Adv.,10, 14386 (2020).

Keywords: Phase transition; Ferromagnetism; Ion-irradiation

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    Joint MMM-INTERMAG, 10.-14.01.2022, New Orleans, United States
  • Lecture (Conference) (Online presentation)
    The 2021 Around-the-Clock Around-the-Globe Magnetics Conference, 21.08.2021, Online, Online
  • Lecture (Conference) (Online presentation)
    6th International Virtual Conference on Nanostructuring by Ion Beams (ICNIB 2021), 05.-08.10.2021, Bhubaneswar, India
  • Poster (Online presentation)
    DPG 2021 - 84. Jahrestagung der DPG und DPG-Tagung der Sektion Kondensierte Materie (SKM), 27.09.-01.10.2021, online, Germany
  • Lecture (others)
    Joint EuFN and FIT4NANO workshop, 27.-30.09.2021, TU Wien, Austria
  • Poster (Online presentation)
    736. WE-Heraeus-Seminar, 05.-08.01.2021, online, Germany
  • Poster
    22nd International Conference on Ion Beam Modification of Materials (IBMM 2022), 10.-15.07.2022, Lisbon, Portugal
  • Lecture (Conference)
    DPG (Spring) Meetings 2022, 04.-09.09.2022, Regensburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-32987
Publ.-Id: 32987


P1902 - Verfahren und Vorrichtung zur Abtrennung von Kunststoffpartikeln

Nikpay, M.

Die Erfindung betrifft eine Verfahren zur Abtrennung von Kunststoffpartikeln aus einer Flüssigkeit oder einem heterogenen Gemisch, das eine Flüssigkeit enthält oder mit einer Flüssigkeit in Kontakt gebracht wird. Dabei ist vorgesehen, dass (a) die Kunststoffpartikel einem Magnetfeld ausgesetzt werden; (b) an der Oberfläche eines Sammlers Kunststoffpartikel adsorbiert werden; und (c) an der Oberfläche des Sammlers adsorbierte Kunststoffpartikel abgeführt werden.

  • Patent
    DE102019103936 - Offenlegung 20.08.2020

Permalink: https://www.hzdr.de/publications/Publ-32986
Publ.-Id: 32986


P1901 - Durchflussmessanordnung und strömungstechnische Anordnung

Arlit, M.; Hampel, U.; Schroth, C.

Eine Durchflussmessanordnung (400) weist einen Messkanal (100) mit einem Messkanaldurchmesser (D0) auf. In dem Messkanal (100) sind ein Strömungsteiler (300) und ein Anemometrie-Gittersensor (500) angeordnet. Der Anemometrie-Gittersensor (500) weist eine Vielzahl von Sensorelementen (510) mit temperaturabhängigem elektrischen Widerstand auf, die lateral voneinander beabstandet sind. Der Strömungsteiler (300) weist eine Vielzahl von Teilkanälen (310) auf. Eine Kanallänge (L1) der Teilkanäle (310) kann kleiner oder gleich dem Messkanaldurchmesser (D0) sein. Ein Abstand (L2) zwischen dem Anemometrie-Gittersensor (500) und dem Strömungsteiler (300) kann kleiner oder gleich dem Messkanaldurchmesser (D0) sein.

  • Patent
    DE102019103674 - Offenlegung 13.08.2020; Nachanmeldungen: WO, EP

Permalink: https://www.hzdr.de/publications/Publ-32985
Publ.-Id: 32985


P1827 - Microfluidic device, apparatus and method for enrichment and dilution of magnetic molecular entities

Mutschke, G.; Yang, X.; AGH Krakau

A microfluidic device (500) includes a substrate (100) with a fluid channel (250) extending from an inlet opening (210) to a channel branch (270). The fluid channel (250) includes a planar spiral portion (255) and at the channel branch (270) 10 the fluid channel (250) branches in at least two outlet channels (280). A ferromagnetic auxiliary structure (300) is formed in a plane parallel to the planar spiral portion (255).

  • Patent
    EP3669982 - Offenlegung 24.06.2020

Permalink: https://www.hzdr.de/publications/Publ-32984
Publ.-Id: 32984


Comparing Metaflow, MLFlow and DVC

Sultova, N.

Blogpost with additional material covering the comparison of Metaflow, MLFlow and DVC for potential usage at HelmholtzAI.

Keywords: machine learning; mlops; devops; python; version management

Permalink: https://www.hzdr.de/publications/Publ-32983
Publ.-Id: 32983


Data publication: A new system for real-time data acquisition and pulse parameterization for digital positron annihilation lifetime spectrometers with high repetition rates

Hirschmann, E.; Butterling, M.; Hernandez Acosta, U.; Liedke, M. O.; Elsherif, A. G. A.; Petring, P.; Görler, M.; Krause-Rehberg, R.; Wagner, A.

Bei diesem Datensatz handelt es sich um die Bilder zur Publikation und Daten für die Leistungskurven

Keywords: Data reduction methods; Digital signal processing (DSP); Detection of defects; Online farms and online filtering

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Permalink: https://www.hzdr.de/publications/Publ-32980
Publ.-Id: 32980


A new system for real-time data acquisition and pulse parameterization for digital positron annihilation lifetime spectrometers with high repetition rates

Hirschmann, E.; Butterling, M.; Hernandez Acosta, U.; Liedke, M. O.; Elsherif, A. G. A.; Petring, P.; Görler, M.; Krause-Rehberg, R.; Wagner, A.

We present a new system for high repetition rate and real-time pulse analysis imple- mented at the Monoenergetic Positron Source (MePS) at the superconducting electron LINAC ELBE at Helmholtz-Zentrum Dresden-Rossendorf. Dedicated digital signal processing and op- timized algorithms are employed allowing for high bandwidth throughput, online pulse analysis and filtering. Positrons generated from radioisotopes and from bremsstrahlung pair production by means of highly intense accelerator-based positron beams serve as a microstructure probe allowing material characterizations with respect to chemical, mechanical, electrical, and magnetic properties. Positron annihilation lifetime events with up to 13 MHz repetition rate are being processed online without losses while performing signal selections for pile-up reduction, online energy calibration, and - for radioisotope-based measurements - identification of start and stop events.

Keywords: Data reduction methods; Digital signal processing (DSP); Detection of defects; Online farms and online filtering

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Permalink: https://www.hzdr.de/publications/Publ-32979
Publ.-Id: 32979


Numerical dimensioning of a pre-cooler for sCO2 power cycles to utilize industrial waste heat

Unger, S.

These are the the processed data of the paper "Numerical dimensioning of a pre-cooler for sCO2 power cycles to utilize industrial waste heat". The data contain the heat transfer and fluid dynamic values of the simulation performed for the corresponding article.

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Permalink: https://www.hzdr.de/publications/Publ-32978
Publ.-Id: 32978


Transport properties of systematically disordered Cr2AlC films

Salgado Cabaco, J.; Kentsch, U.; Lindner, J.; Faßbender, J.; Leyens, C.; Bali, R.; Boucher, R.

Nano-lamellar composite materials, known as MAX-phases, can possess a combination of ceramic and metallic properties. A prototype compound is Cr2AlC, formed from a unit cell of Cr2C sandwiched between atomic planes of Al, thereby imparting a good electrical conductivity, as well as mechanical stability, radiation and oxidation resistance [1, 2]. These properties rely on the lamellar structure of the compound, and systematic introduction of defects, such as displacing or doping atoms within the layers, has the potential to tune electron transport and modify magnetic properties [3]. An ideal tool for defect implantation is ion-irradiation, available both in the form of a broad-beam for wafer-scale processing as well as focused ion-beams for device prototyping. Here we observe the modifications to the structural, transport and magnetic behavior of 500 nm thick Cr2AlC after irradiation with Co+ ions, and Ar+ noble gas ions as control. The films were irradiated with 450 keV of Co+ ions at fluences varying from 5E12 to 5E15 ions.cm-2, and the control samples with 400 keV Ar+ ions keeping the sample fluences. Structural analysis using XRD shows that ion-irradiation induces a suppression of the 0002 reflection, indicating a gradual decay of the nano-lamellar structure. Increasing ion-fluence also leads to an increase of the saturation magnetization at 1.5 K, whereby both Ar+ and Co+ cause an increased magnetization, respectively to 150 and 190 kA.m-1, for the highest fluences used. Large variations of the transport properties are observed. Magnetoresistance (MR) in the non-irradiated sample shows a classical B2 dependency, even up to high temperatures. At Co+ fluences of 5E13 ions.cm-2 the MR shows a two orders of magnitude increase, up to 3% (10 T) at 100 K. A similar effect also occurs for 5E12 ions.cm-2 Ar+ irradiated films, however with a smaller MR-increase. It appears that resistivity increases and the residual resistance ratio reduces with increasing fluence due to the introduction of disorder. These results show that ion irradiation induces significant changes in the transport properties of MAX phase materials, that will be further investigated. The systematic disordering of nano-laminated MAX phase films may therefore reveal interesting disorder and spin-related transport phenomena.

Funding by the Deutsche Forschungsgemeinschaft (DFG) - Project number 456078299 is acknowledged. Ion-irradiation has been performed at the Ion Beam Centre of the HZDR.
[1] A. S. Ingason, M. Dahlqvist, J. Rosen, Magnetic MAX phases from theory and experiments; a review; J. Phys.: Condens. Matter 28, 433003, (2016). [2] M. W. Barsoum, MAX Phases: Properties of Machinable Ternary Carbides and Nitrides; Weinheim: Willey-VCH (2013). [3] C. Wang, T. Yang, C. L. Tracy, C. Lu, H. Zhang, Y.-J. Hu, L. Wang, L. Qi, L. Gu, Q. Huang, J.Zhang, J. Wang, J. Xue, R. C. Ewing, Y. Wang, Disorder in Mn+1AXn phases at the atomic scale, Nature Communications 10, 622 (2019).

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  • Poster (Online presentation)
    International workshop on functional MAX-materials. 2nd FunMax, 14.-17.09.2021, Krasnoyarsk, Russia

Permalink: https://www.hzdr.de/publications/Publ-32977
Publ.-Id: 32977


Targeting glutamine metabolism and autophagy: the combination for prostate cancer radiosensitization

Mukha, A.; Kahya, U.; Dubrovska, A.

Radiotherapy is one of the curative mainstays of prostate cancer; however, its efficacy is often diminished by tumor radioresistance. Depending on the stage of disease, tumors can relapse in approximately 50% of patients with prostate cancer after radiotherapy. Nevertheless, the mechanisms that drive tumor cell survival are not fully characterized, and reliable molecular prognostic markers of prostate cancer radioresistance are missing. Similar to other tumor entities, prostate cancer cells are heterogeneous in their capability to maintain tumor growth. The populations of cancer stem cells (CSC) with self-renewal and differentiation properties are responsible for tumor development and recurrence after treatment. Eradication of these CSC populations is of utmost importance for efficient tumor cure. In a recently published study, we showed that prostate cancer cells could be radiosensitized by glutamine deprivation, resulting in DNA damage, oxidative stress, epigenetic modifications, and depletion of CSCs. Conversely, prostate cancer cells with resistance to glutamine depletion show an activation of ATG-mediated macroautophagy/autophagy as a survival strategy to withstand radiation-induced damage. Thus, a combination of targeting glutamine metabolism and autophagy blockade lead to more efficient prostate cancer radiosensitization.

Keywords: ATG5; CSC; glutaminase; tricarboxylic acid cycle

Permalink: https://www.hzdr.de/publications/Publ-32974
Publ.-Id: 32974


Experimental characterization of liquid metal bubble-driven flows modeling the situation in a steel ladle

Wondrak, T.; Bruch, C.; Eckert, S.; Gardin, P.; Hackl, G.; Lachmund, H.; Lüngen, H. B.; Odenthal, H.-J.; Timmel, K.; Willers, B.

In metallurgy, gas-liquid two-phase flows are relevant for mixing, degassing and refinement. The reliable prediction of the hydrodynamic performance in gas-stirred ladles is of utmost relevance for optimization and process control. A new experimental facility has been designed and constructed for systematic investigations of gas bubbles rising inside the alloy SnBi, its thermophysical properties are very similar to those of steel. Low operating temperatures (T~200°C) allow the use of powerful measuring techniques. The cylindrical fluid vessel represents a 1:5.25 model of an industrial 185 t ladle and is equipped with a vacuum pump to achieve low-pressure conditions for VOD (Vacuum Oxygen Decarburization) applications as well. The experiments provide a copious data base about the flow regimes, void fraction, liquid and bubble velocities, and bubble properties, which can be used to provide so far unknown boundary conditions for CFD simulations of various metallurgical reactors such as steelmaking converters or steelmaking ladles.

Keywords: two-phase flow; liquid metal; bubble measurement

Permalink: https://www.hzdr.de/publications/Publ-32973
Publ.-Id: 32973


RawData for paper: Mounted Single Particle Characterization for 3D Mineralogical Analysis - MSPaCMAn

Da Assuncao Godinho, J. R.

Raw 3D images of the 3 types of samples used in the paper

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Permalink: https://www.hzdr.de/publications/Publ-32972
Publ.-Id: 32972


Manipulation of antiferromagnetism with electric fields: from fundamentals to memory concepts

Makarov, D.

Thin film antiferromagnets (AF) have potential to revolutionize spintronics due to their inherently magnetic-field stable magnetic order and high-frequency operation. To explore their application potential, it is necessary to understand modifications of the magnetic properties and magnetoelectric responses of AF thin films with respect to their bulk counterparts. Considering grainy morphology of thin films, questions regarding the change of the intergranular exchange, criticality behavior and switching of the order parameter need to be addressed.
Our approach is based on the electron transport characterization of magnetic responses of thin film antiferromagnets [1-4]. This task is difficult as minute uncompensated surface magnetization of antiferromagnets needs to be detected, which imposes strict requirements to the sensitivity of the method. We will outline our developments of zero-offset anomalous Hall magnetometry [1] applied to study the physics of conventional metallic IrMn and insulating magnetoelectric Cr2O3 antiferromagnets. To build a reliable description of the material properties, the analysis of the transport data is backed up by structural characterization and real space imaging of AF domain patterns using NV microscopy [2,5]. Based on this unique and novel combination, we for the first time observe the formation of nanoscale antiferromagnetic domains in thin films of Chromia (Cr2O3) across its ordering temperature at ~300 K. Our quantitative results yield a detailed understanding of the domain formation process in Cr2O3 and allow us to determine the efficiency of inter-granular magnetic exchange coupling [5]. This coupling strength has proven decisive in the decades long development of ferromagnetic memory media and will be of equal importance for future antiferromagnetic spintronics technologies.
The fundamental understanding of the magnetic microstructure of magnetoelectric α-Cr2O3 thin films and the possibility to read-out its antiferromagnetic order parameter all-electrically enabled the entirely new recording concept where a magnetoelectric memory cell can be addressed without using a ferromagnet. With this approach, we opened an appealing topic of purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) [2].
By exploring the interaction of antiferromagnetic domain walls with morphological structures prepared on the surface of Cr2O3 single crystals, we access the nanoscale mechanics of AF domain walls [6,7]. We propose to employ nanoscale patterns as engineered pinning centers for AF domain walls, where binary information is encoded by the direction of the Neel vector. Our results bear significant potential for technological exploitation be it in the form of the proposed antiferromagnetic memory devices, or ultimately for the realisation of DW logic using antiferromagnets.
These recent developments on the fabrication and characterization of Cr2O3-based functional elements will be discussed in this presentation.

[1] T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, D. Makarov, “All-Electric access to the Magnetic-Field-Invariant Magnetization of Antiferromagnets”, Phys. Rev. Lett. 115, 097201 (2015).
[2] T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, and D. Makarov, “Purely antiferromagnetic magnetoelectric random access memory”, Nature Communications 8, 13985 (2017).
[3] R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, and S. T. B. Goennenwein, “Evolution of the spin hall magnetoresistance in Cr2O3/Pt bilayers close to the Neel temperature”, Appl. Phys. Lett. 112, 132401 (2018).
[4] P. Muduli, R. Schlitz, T. Kosub, R. Hübner, A. Erbe, D. Makarov, and S. T. B. Goennenwein, “Local and nonlocal spin Seebeck effect in lateral Pt-Cr2O3-Pt devices at low temperatures”, Appl. Phys. Lett. Materials 9, 021122 (2021).
[5] P. Appel, B. J. Shields, T. Kosub, R. Hübner, J. Fassbender, D. Makarov, and P. Maletinsky, “Nanomagnetism of magnetoelectric granular thin film antiferromagnets”, Nano Letters 19, 1682 (2019).
[6] O. V. Pylypovskyi, A. V. Tomilo, D. D. Sheka, J. Fassbender, and D. Makarov, “Boundary conditions for the Neel order parameter in a chiral antiferromagnetic slab”, Phys. Rev. B 103, 134413 (2021).
[7] N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, and P. Maletinsky, “Nanoscale mechanics of antiferromagnetic domain walls”, Nature Physics (2021). https://doi.org/10.1038/s41567-020-01157-0.

Keywords: antiferromagnetic spintronics; magnetoelectric effect

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  • Invited lecture (Conferences) (Online presentation)
    school in the frame of the COST Action MAGNETOFON – “Ultrafast opto-magneto-electronics for non-dissipative information technology” (https://magnetofon.science.ru.nl), 05.-08.10.2021, Samobor, Croatia

Permalink: https://www.hzdr.de/publications/Publ-32970
Publ.-Id: 32970


Curvilinear magnetism

Makarov, D.

Conventionally, tailoring of the Dzyaloshinskii-Moriya interaction (DMI) is done by optimizing materials, either doping a bulk single crystal or adjusting interface properties of thin films and multilayers. A viable alternative to the conventional material screening approach is to explore the interplay between the sample geometry and topology of the order parameter. The research field in magnetism, which is dealing with the study of the impact of geometrical curvature on magnetic responses of curved 1D wires and 2D shells is known as curvilinear magnetism [1-4]. The lack of the inversion symmetry and the emergence of a curvature induced effective anisotropy and DMI stemming from the exchange interaction [5,6] are characteristic of curved surfaces, leading to curvature-driven magnetochiral effects. Volkov et al. has proven that the exchange-driven chiral effects in curvilinear ferromagnets are experimental observables [7] and can be used to realize nanostructures with tunable magnetochiral properties from standard magnetic materials.
A counterpart of the intrinsic DMI for the case of curvilinear magnets is the mesoscale Dzyaloshinskii-Moriya interaction, which is a result of the interplay between the intrinsic (spin-orbit-driven) and extrinsic (curvature-driven) DMI terms [8]. The mesoscale DMI governs the magnetochiral properties of any curvilinear ferromagnetic nanosystem and depends both on the material and geometrical parameters. Its strength and orientation can be tailored by properly choosing the geometry, which allows stabilizing distinct magnetic chiral textures including skyrmion and skyrmionium states as well as skyrmion lattices [9-11]. Interestingly, skyrmion states can be formed in a material even without an intrinsic DMI [9,11]. Very recently, Sheka et al. discovered a novel non-local chiral symmetry breaking effect, which does not exist in planar thin film magnets: it is essentially non-local and manifests itself even in static spin textures living in curvilinear magnetic nanoshells [6].
The field of curvilinear magnetism was recently extended towards curvilinear antiferromagnets. Pylypovskyi et al. demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnet behaves as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [12,13]. This positions curvilinear antiferromagnets as a novel platform for the realization of geometrically tunable chiral antiferromagnets for antiferromagnetic spinorbitronics.
The application potential of 3D-shaped magnetic thin films is currently being explored as mechanically shapeable magnetic field sensors [14,15] for automotive applications, magnetoelectrics for memory devices, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics [16-18].
The fundamentals as well as application relevant aspects of curvilinear ferro- and antiferromagnets will be covered in this presentation.

[1] D. Makarov et al., Adv. Mater. (2021). doi:10.1002/adma.202101758
[2] R. Streubel et al., J. Phys. D: Appl. Phys. 49 (2016), 363001.
[3] D. Sander et al., J. Phys. D: Appl. Phys. 50 (2017), 363001.
[4] E. Vedmedenko et al., J. Phys. D: Appl. Phys. 53 (2020), 453001.
[5] Y. Gaididei et al., Phys. Rev. Lett. 112 (2014), 257203.
[6] D. Sheka et al., Communications Physics 3 (2020), 128.
[7] O. Volkov et al., Phys. Rev. Lett. 123 (2019), 077201.
[8] O. Volkov et al., Scientific Reports 8 (2018), 866.
[9] V. Kravchuk et al., Phys. Rev. B 94 (2016), 144402.
[10] V. Kravchuk et al., Phys. Rev. Lett. 120 (2018), 067201.
[11] O. Pylypovskyi et al., Phys. Rev. Appl. 10 (2018), 064057.
[12] O. Pylypovskyi et al., Nano Letters 20 (2020), 8157.
[13] O. Pylypovskyi et al., Appl. Phys. Lett. 118 (2021), 182405.
[14] S. Canon Bermudez et al., Adv. Funct. Mater. (2021). doi:10.1002/adfm.202007788
[15] D. Makarov et al., Appl. Phys. Rev. 3 (2016), 011101.
[16] S. Canon Bermudez et al., Science Advances 4 (2018), eaao2623.
[17] S. Canon Bermudez et al., Nature Electronics 1 (2018), 589.
[18] J. Ge et al., Nature Communications 10 (2019), 4405.

Keywords: curvature effects in magnetism; flexible magnetic field sensors

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  • Lecture (others) (Online presentation)
    physics colloquium at the University of Nebraska-Lincoln, 18.11.2021, Lincoln, USA

Permalink: https://www.hzdr.de/publications/Publ-32969
Publ.-Id: 32969


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