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33407 Publications

Simulation of Scaled Core-Meltdown-Experiments and Investigation of a Possible Vessel Support against Failure

Willschütz, H.-G.; Altstadt, E.; Weiss, F.-P.; Sehgal, B. R.
At present the scaled core melt down experiments FOREVER are underway. These experiments are simulating the lower head of a reactor pressure vessel under the load of a melt pool with internal heat sources. Due to the multiaxial creep deformation of the three-dimensional vessel with a highly non-uniform temperature field these experiments are an excellent possibility to validate numerical creep models. A Finite Element model is developed and using the Computational Fluid Dynamic module the temperature field within the vessel wall is evaluated. The transient structural mechanical calculations are then performed applying a new creep model procedure. Additionally the material damage is evaluated considering the creep deformation as well as the prompt plasticity.
After post-test calculations for the FOREVER-C2 experiment, pre-test calculations for the experiments to come are performed. Taking into account both - experimental and numerical results - gives a good opportunity to improve the simulation and understanding of real accident scenarios. Analysing the calculations it seems to be advantageous to introduce a vessel support which can disburden the vessel from a part of the mechanical load and therefore avoid the vessel failure or at least prolongate the failure time as a possible accident mitigation strategy. Additionally, it seems to be possible to install an absolutely passive automatic control device to initiate the flooding of the reactor pit to ensure external vessel cooling in case of a core melt down.
Keywords: FOREVER-Experiment, Coupling of Thermo-Fluid Dynamic and Structural Mechanical FE-Model, Advanced Creep Modelling, Vessel Support as Accident Mitigation Strategy
  • Lecture (Conference)
    16th International Conference on Structural Mechanics in Reactor Technology SMiRT16, Washington, DC, USA, August 12-17, 2001, Paper No. 1145
  • Contribution to proceedings
    16th International Conference on Structural Mechanics in Reactor Technology SMiRT16, Washington, DC, USA, August 12-17, 2001, Paper No. 1145

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Permalink: https://www.hzdr.de/publications/Publ-3832
Publ.-Id: 3832


Effect of temperature on the emission characteristics of liquid metal alloy ion sources

Bischoff, L.; Teichert, J.; Ganetsos, T.; Mair, G. L. R.
In spite of the fact that a great deal of research has been carried out on liquid metal ion sources, suprisingly few results exist on the temperature dependence of their emission characteristics. In this article we study two liquid metal alloy ion sources (LMAISs), namely Co36Nd64 and Au77Ge14Si9. While the results of the former source were as expected, the latter displayed an entirely different dependence of its emission characteristics on temperature. The unusual results of the Au77Ge14Si9 LMAIS are explained in terms of the abnormal behavior of the surface tension of the alloy with temperature.
Keywords: liquid metal alloy ion source, temperature dependence, emission behavior
  • Journal of Vacuum Science and Technology B19 (1) 2001 76 -78

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Permalink: https://www.hzdr.de/publications/Publ-3830
Publ.-Id: 3830


Investigation on multiphase and multicomponent flows - experiments and measurement devices

Schaffrath, A.; Krüssenberg, A.-K.
Vertical two-phase flow is normally classified into the four basic flow regimes bubble, slug, churn and annular flow. The transition between the different flow regimes does not occur suddenly and many extensions of this classification can be found in literature. For the prediction of flow patterns empirical and theoretical flow pattern maps have been developed.
  • Lecture (others)
    Politecnico di Milano, Dipartimento di Ingegneria Nucleare, 13.03.2000, Milano, Italy

Permalink: https://www.hzdr.de/publications/Publ-3823
Publ.-Id: 3823


A mineral-specific thermodynamic sorption database

Brendler, V.; Arnold, T.; Bernhard, G.; Fanghänel, T.
This paper presents a digitized version of a thermodynamic sorption database, implemented as a relational database under MS Access. The data are required for the parametrization of Surface Complexation Models (SCM). It is mineral-specific and can therefore also be used for additive models of more complex solid phases such as rocks or soils. An integrated user interface helps users to access selected mineral and sorption data, to convert parameter units, to extract internally consistent data sets for sorption modeling, and to export them into formats suitable for other modeling software. Data records comprise of mineral properties, specific surface area values, characteristics of surface binding sites and their protolysis, sorption ligand information, and surface complexation reactions. The following submodels are already implemented, extensions to other variants are straightforward: the Non-Electrostatic Model, the Diffuse Double Layer Model, the Constant Capacitance Model, the Triple Layer Model, and the Basic Stern Model. For every SCM type (where applicable), also the concept of strong and weak binding sites, and the 1-pK approach is included. Surface species composed from up to three different ligands can be incorporated.
An extensive bibliography is also included, providing links not only to the above listed data items, but also to background information concerning surface complexation model theories, related software for data processing and modeling, and sorption experiment techniques. Only very few of the abundant surface complexes proposed in the literature (mostly resulting just from best-fit considerations) are actually validated by spectroscopic evidence or supported by theoretical (quantum-chemical) calculations. If such information is available it is also stored in the database.
The database will help to substitute the at present in risk assessment studies most often applied simplistic distribution coefficients (Kd-values) by the more realistic description of sorption phenomena with SCM. It assists the identification of critical data gaps, the evaluation of existing parameter sets, consistency tests and the establishment of selected reference data sets. As to the knowledge of the authors, so far there is no such digital thermodynamic database for surface complexation equilibria existent world-wide, despite the vast amount of available data.



  • Lecture (Conference)
    Migration 2001, Bregenz, Österreich, 16.-21.09.2001

Permalink: https://www.hzdr.de/publications/Publ-3822
Publ.-Id: 3822


Structure parameter analysis of Cu(UO2Aso4)2 nH2 using EXAFS spectroscopy

Hennig, C.; Reich, T.; Funke, H.; Roßberg, A.; Rutsch, M.; Bernhard, G.
kein Abstract vorgesehen
  • Poster
    ESRF Meeting, Grenoble, Frankreich, 19.-21.02. 2001

Permalink: https://www.hzdr.de/publications/Publ-3821
Publ.-Id: 3821


The effect of secondary iron mineral and colloid formation on uranium sorption during the dissolution of chlorite

Krawczyk-Bärsch, E.; Arnold, T.; Hüttig, G.; Zänker, H.; Brandt, F.; Bernhard, G.
Chlorite is a common accessory mineral, commonly found in sedimentary and low grade metamorphic rocks like the phyllite in the former uranium mining area of Saxony (Germany). The cur-rent flooding of the mines leads to an interaction be-tween the uranium containing flooding water and the surfaces of the wall rock. During the weathering of phyllite a secondary mineral is formed, which in further investigations [1] was described as ferrihydrite. The source of this secondary mineral is the iron-rich chlo-rite of the phyllite.
Chlorite is a phyllosilicate with a trioctahedral structure, consisting of negatively charged 2:1 layers that alternate regularly with positively charged interlayer sheets [2]. During the weathering of chlorite the main constituents of the octahedral sheets, Mg2+, Fe2+, Fe3+ and Al3+, are released into the aqueous solu-tions. In laboratory experiments the dissolution of chlo-rite was studied with a continuous flow-through reactor and in batch experiments. In this study we will lay em-phasis on the released iron because of its ability to form secondary minerals and colloids.
Experiments: Batch experiments were carried out on an iron-rich chlorite from Flagstaff Hill, California, with a grain size of 63-200 µm. Half a gram of the samples were added to 40 ml deionized water, which was previously adjusted to an ionic strength of 0.1 M with NaClO4. The suspension was aged during 2 months without any pH adjustment. A pH value of 7 was found at the end of the experiment. The freshly formed iron hydroxide particles were separated from the large excess of the micron-size chlorite powder particles by well-defined centrifugations (2500 x g, 1h and 3500 x g, 1h). A defined volume of the centrifugate was filtered through a 50 nm and 15 nm Nuclepore filter in order to fix the ultrafine iron particles on a substrate. The filter membranes were prepared for scanning electron microscopy (SEM).
Results: In SEM investigations spherical particles are detected on the Nuclepore filter. The size of these colloids ranges from 30 to 80 nm. The colloids are mainly arranged as agglomerates, while individual colloids are rarely observed. On several large agglom-erates energy-dispersive X-ray analysis (EDS) were taken in order to get information about the chemistry of these colloids. With this method we were able to detect directly iron colloids of a chlorite suspension at pH 7. The process leading to the formation of colloids can be explained as a consequence of the iron release during the dissolution of chlorite. The dissolved iron oxidizes to ferric iron which subsequently hydrolyses, precipi-tates and forms secondary minerals and iron colloids. The detection of iron colloids was previously described in a suspension of ground phyllite [3], where a com-bined technique of centrifugation at varying centrifugal speed and ICP-MS and AAS of the centrifugates was used. The formation of iron colloids was prevented in the acid region of pH = 4 due to the higher solubility of Fe in this pH region. With decreasing solubility in the neutral and alkaline medium, the released Fe forms iron colloids or precipitates as secondary iron mineral coatings. The formation of iron colloids during the dissolu-tion of chlorite must be taken into consideration in the assessment of contaminant behavior in the nature. Though contributing only little to the mass balance of a water body, iron colloids can show significant adsorp-tion of trace elements because of their high specific surface area and their affinity to heavy metals.
The formation of secondary iron mineral coatings is also of importance for the behavior of contaminants in the nature since coatings significantly change the sur-face properties of the weathering chlorite. The most common secondary iron mineral is ferrihydrite, a poorly crystallized iron mineral with a chemical for-mula of 5Fe2O3 . 9H2O [4] and a large specific surface area. Sorption experiments which were carried out with ur...
  • Lecture (Conference)
    Goldschmidt Conference, Hot Springs, Virginia, USA , 19.5. - 24.5.2001

Permalink: https://www.hzdr.de/publications/Publ-3820
Publ.-Id: 3820


Complexation of Cm(III) and Eu(III) by glycolic acid: TRLFS studies

Stumpf, T.; Fanghänel, T.; Grenthe, I.; Kim, J. I.
Complexation processes of Cm(III) and Eu(III) by glycolic acid are studied by time-resolved laser fluorescence spectroscopy (TRLFS). The experiments with curium are performed in 0.1 M and 3.0 M NaClO4. The glycolic acid concentration is varied between 0.01 mol/L and 0.5 mol/L at pH 3. Cm(III) and Eu(III) fluorescence emission spectra are obtained at a fixed glycolic acid concentration of 0.5 mol/L, the pH is varied between 3 and 11. In addition to the Cm3+ aquo ion, two Cm(III)-glycolic acid species are observed by peak deconvolution: Cm(gly)2+ and Cm(gly)2+. Above pH 5 a chelate Cm-glycolate complex is formed. This curium-glycolate complex is characterised by its emission spectrum (peak maximum at 611.2 nm) and its fluorescence emission lifetime (172 ± 8 µs). The corresponding chelate europium-glycolate complex with 300 ± 10 µs lifetime is obtained above pH 6.83. In the pH range 6 to 8 the decay behaviour of the excited state is different in the Cm(III)- and Eu(III)-glycolate system. While a bi-exponential decay behaviour was observed for the Cm-system, indicating slow exchange kinetics in comparison to the fluorescence decay of the exited state, the corresponding Eu-system shows mono-exponential decay behaviour. More over the reversibility of Eu-chelating is much faster than in the case of the Cm(III) complex. The results show that the strength and kinetics of the chelating is different for Cm(III) and Eu(III).

  • Lecture (Conference)
    Actinides-2001, Hayama, Japan vom 4. - 9. November 2001.

Permalink: https://www.hzdr.de/publications/Publ-3818
Publ.-Id: 3818


The NOKO/TOPFLOW Facility for Natural Convection Flow

Hicken, E.-F.; Jaegers, H.; Schaffrath, A.; Weiß, F.-P.
For the study of the effectiveness of passive safety systems a high pressure (up to 7 MPa) and high power (up to 4 MW) test facility – named NOKO – has been constructed and operated at the Forschungszentrum Jülich. From 1996-1998 this facility was used for a project within the 4th FP of the EU "European BWR R&D Cluster for Innovative Passive Safety Systems". An overview and selected results are given for the tests with two bundles of the emergency condenser, with the building and plate condenser, with 4 different passive initiators, with a passive flooding system and with decay heat removal tests during shutdown.
It has been decided to decrease substantially the safety research at the Forschungszentrum Jülich; to maintain the experimental competence for two-phase flow the NOKO facility will be transferred to the Forschungszentrum Rossendorf by the end of the year 2000 up to the beginning of the year 2001. The facility will be named TOPFLOW; the main objectives of future tests will be oriented towards more generic research: investigation of steady state and transient two phase flow phenomena especially transient two phase flow patterns, the development of two-phase flow instrumentation, the generation of a data basis for Computational Fluid Dynamic (CFD)-Code validation and testing of heat exchangers and safety systems. An overview will be given about the modifications and improvements related to the test facility and the planned test.
  • Lecture (Conference)
    Technical Committee Meeting on Natural Circulation Data and Methods for Innovative Nuclear Power Plant Design, Session 3, International Atomic Energy Agency, Vienna (Austria), July 18-21, 2000
  • Contribution to proceedings
    Technical Committee Meeting on Natural Circulation Data and Methods for Innovative Nuclear Power Plant Design, Session 3, International Atomic Energy Agency, Vienna (Austria), July 18-21, 2000

Permalink: https://www.hzdr.de/publications/Publ-3807
Publ.-Id: 3807


Neutron Flux Uncertainty and Covariances for Spectrum Adjustment and Estimations of Pressure Vessel Fluences

Böhmer, B.; Manturov, G.
Results of estimations of covariance matrices of neutron spectra in VVER-1000 reactor pressure vessel and cavity positions are presented. Two-dimensional calculations with the discrete ordinates transport code DORT in r-theta and r-z-geometries are used to determine the neutron group spectrum covariances including cross-correlations between interesting positions. The new Russian ABBN-93 data set and the CONSYST code are used to supply the transport calculations with neutron group data. All possible sources of uncertainties, as neutron cross sections, fission sources, geometrical dimensions and material densities, were considered, whereas, the uncertainty of the calculation method was assumed to be negligible in view of the available precision of Monte Carlo simulation.
Keywords: fluence covariance, spectrum adjustment, uncertainty analysis, cross-correlation, reactor pressure vessel, reactor dosimetry
  • Lecture (Conference)
    Tenth Symposium of AER on Reactor Physics and Reactor Safety 2000, Moscow (Russia) 18 - 22 September 2000, Proceedings, Vol. I, pp. 345-351
  • Contribution to proceedings
    Tenth Symposium of AER on Reactor Physics and Reactor Safety 2000, Moscow (Russia) 18 - 22 September 2000, Proceedings, Vol. I, pp. 345-351

Permalink: https://www.hzdr.de/publications/Publ-3802
Publ.-Id: 3802


Technical description of the radiological safety system for X-ray absorption spectroscopy experiments on radioactive samples at the Rossendorf Beamline

Funke, H.; Bernhard, G.; Reich, T.; Matz, W.; Oehme, W.; Claußner, J.; Jansen, K.-H.; Röllig, D.; Nitsche, H.
The Rossendorf Beamline at the European Synchrotron Radiation Facility is equipped with a unique radiochemistry experimental station. This dedicated station has been designed to perform environmentally relevant experiments on radionuclides, in particular actinides, using synchrotron based X-ray absorption fine structure spectroscopy. The technical concepts and the layout of this experimental station, where radioactive solids and liquids with activities of up to 185 MBq can be studied, are presented. The radiological safety of experimenters, equipment, and of the environment are ensured by the specially developed radiochemistry safety system. The multibarrier concept, the ventilation and air monitoring systems, the radiological protection system, and special software components for recording and visualisation of the safety status are described in detail.

  • Kerntechnik 66(2001) 195-201

Permalink: https://www.hzdr.de/publications/Publ-3801
Publ.-Id: 3801


Dihydrotetra(4­picoline)siliconchloride­Hexakis­chloroform

Stumpf, T.; Bolte, M.
The title compound, [C24H30N4Si]2+·2Cl-·6CHCl3, contains a hexacoordinated Si atom located on a crystallographic centre of inversion. The coordination of the Si atom can be described as a slightly distorted octahedron, with the 4-picoline ligands in the equatorial plane and the two H atoms occupying axial positions. The title compound is isomorphous with its analogue where the Cl ions are substituted by Br ions.

Acta Cryst. (2001) E (submitted)
  • Acta Crystallographie

Permalink: https://www.hzdr.de/publications/Publ-3800
Publ.-Id: 3800


Interaction of Neptunium(V) with Humic Acids of Different Functionalities

Sachs, S.; Schmeide, K.; Geipel, G.; Reich, T.; Heise, K. H.; Bernhard, G.
In order to improve models used for the predictive modeling of the actinide migration in natu-ral aquifer systems it is necessary to get more precise information about the interaction process between humic acids and actinide ions. This includes for instance a more profound knowledge about humic acid binding sites interacting with actinide ions at different pH values. In addition, natural humic acids contain small amounts of inorganic components, e.g., iron, that cannot be removed by usual purification methods. It is not known whether or not these components may influence the interaction between humic acids and actinide ions.
Applying humic acid model substances and natural humic acids with different functionalities we continue our studies concerning the interaction between humic acids and actinides [e.g., 1,2]. In order to specify humic acid binding sites interacting with actinide ions in the neutral pH range, we study the influence of phenolic OH and other acidic OH groups on the interaction process. We investigate the neptunium(V) complexation in neutral solution by near infra-red absorption spectroscopy and X-ray absorption spectroscopy applying modified synthetic and natural humic acids with blocked phenolic and other blocked acidic OH groups. The influence of inorganic humic acid components on the actinide complexation by humic acids is studied using an "ultra-pure" synthetic humic acid model substance. The neptunium(V) com-plexation of this humic acid is compared to the complexation behavior of natural and synthetic humic acids having small amounts of non-removable inorganic components.

[1] Pompe, S. et al.: Determination and Comparison of Uranyl Complexation Constants with Natural and Model Humic Acids. Radiochim. Acta 82, 89 (1998).
[2] Pompe, S. et al.: Investigation of Humic Acid Complexation Behavior with Uranyl Ions Using Modified Synthetic and Natural Humic Acids. Radiochim. Acta 88, 553 (2000).

Keywords: Humic acid, Synthetic humic acid, Modified humic acid, Phenolic OH groups, Complexation, Neptunium, X-ray absorption spectroscopy, Near infrared absorption spectroscopy
  • Poster
    8th International Conference on Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere Migration'01,16.-21.September 2001, Bregenz, Austria
  • Lecture (Conference)
    8th International Conference on the Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere-Migration'01, 16.-21. September, Bregenz, Austria.

Permalink: https://www.hzdr.de/publications/Publ-3799
Publ.-Id: 3799


Synthesis and preliminary evaluation of N1-methyl-9-[1-hydroxy-3-[18F]fluoro-2-propoxy)methyl]guanine [18F]MFHPG, a new substrate of HSV-1-thymidine kinase

Noll, B.; Noll, S.; Scheunemann, M.; Brust, P.; Friedrich, A.; Hauses, M.; Schackert, H. K.
no abstract delivered from author
  • Poster
    14th International Symposium on Radiopharmaceutical Chemistry, Interlaken, Switzerland, 10.-15.06.2001

Permalink: https://www.hzdr.de/publications/Publ-3796
Publ.-Id: 3796


Geschwindigkeitsmessungen im Downcomer der ROCOM Versuchsanlage mittels Laser-Doppler Anemometrie im Vergleich mit numerischen Berechnungen

Höhne, T.; Grunwald, G.; Prasser, H.-M.
Abstract

An der Vermischungsanlage ROCOM, einem 1:5 skalierten Modell des Druckwasserreaktors Konvoi wurden umfangreiche Geschwindigkeitsmessungen im Downcomer des Reaktordruckbehälters für verschiedene Schleifendurchsätze und Teilschleifenbetrieb durchgeführt. Durch Verwendung eines leistungsfähigen Lasers konnten auch transiente Geschwindigkeitsprofile aufgenommen werden. Einige der gemessenen Profile wurden mit dem numerischen Strömungsberechnungsprogramm CFX-4 nachgerechnet.

Bei Vierschleifenbetrieb konnte eine Unabhängigkeit der Geschwindigkeitsprofile von der Reynoldszahloberhalb über 100 m³/h pro Schleife im Modell nachgewiesen werden. Im Vergleich zu anderen Reaktortypen bestehen im Ringraum des RDB des DWR Konvoi einige konstruktive Besonderheiten, die die Vermischung nachhaltig beeinflussen. Der Downcomer ist verhältnismäßig kurz und besitzt eine diffusorartige Erweiterung unterhalb der Stutzenebene. Unterhalb der Eintrittsstutzen und Austrittsstutzen existieren Rezirkulationsgebiete mit geringen Geschwindigkeitsgradienten. Zwischen den Eintritts- und Austrittsstutzen liegen Gebiete hoher Geschwindigkeitsgradienten. Transiente Messungen bei Anfahren einer Pumpe belegen, daß die Strömung im Downcomer in den ersten Sekunden wie eine Potentialströmung anläuft. Das Geschwindigkeitsmaximum befindet sich dabei noch annähernd unterhalb des entsprechenden Kühlmittelstutzens. Erst mit einer gewissen Zeitverzögerung entwickeln sich die großräumigen Wirbelgebiete, die letztlich zum Geschwindigkeitsmaximum auf der der in Betrieb gegangenen Schleife entgegengesetzten Seite des Ringspalts führen.

Strömungsuntersuchungen im Downcomer mit Hilfe der LDA-Technik bei naturumlaufnahen Schleifendurchsätzen mit Hinzugabe von Glucose zur Simulation von Dichteeffekten sind geplant.
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-334 Oktober 2001

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Permalink: https://www.hzdr.de/publications/Publ-3795
Publ.-Id: 3795


S-[18F]fluoromethyl-(+)-McN5652, evaluation in rats as a tracer for the serotonin transporter

Marjamäki, P.; Zessin, J.; Eskola, O.; Bergman, J.; Grönroos, T.; Haaparanta, M.; Lehikoinen, P.; Forsback, S.; Brust, P.; Steinbach, J.; Solin, O.
The S-[18F]fluoromethyl analogue of (+)-McN5652 was evaluated by autoradiographic ex vivo studies with rats.
Keywords: (+)-McN5652, [18F]fluoromethyl analogue, [18F]bromofluoromethane, PET, autoradiography, serotonin transporter
  • Poster
    12th International Symposium on Radiopharmacology, 12.-15.06.2001, Interlaken, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-3794
Publ.-Id: 3794


S-[18F]fluoromethyl-(+)-McN5652 - A potential PET tracer for imaging the serotonin transporter

Zessin, J.; Eskola, O.; Brust, P.; Berman, J.; Marjamäki, P.; Kretzschmar, M.; Grönroos, T.; Wittrisch, H.; Haaparanta, M.; Lehikoinen, P.; Solin, O.; Steinbach, J.; Johannsen, B.
The S-[18F]fluoromethyl analogue of (+)-McN5652 was prepared by reaction of demethylated (+)-McN5652 with [18F]bromofluoromethane in decay-corrected radiochemical yields of about 18% (related to [18F]fluoride). Autoradiographic ex vivo studies with rats and PET studies with piglets indicate that the 18F-labelled analogue of (+)-McN5652 is a potential PET tracer for the imaging of the serotonin transporter.
Keywords: McN5652, [18F]bromofluoromethane, PET, serotonin transporter
  • Lecture (Conference)
    14th International Symposium on Radiopharmaceutical Chemistry, 10 - 15.6.2001, Interlaken, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-3793
Publ.-Id: 3793


Neptunium(V) Sorption onto Granite and its Mineral Constituents in the Absence and Presence of Humic Acid

Schmeide, K.; Sachs, S.; Reich, T.; Hennig, C.; Heise, K. H.; Bernhard, G.
In Germany, besides salt formations also granitic subsurface environments are taken into account as potential host formations for the geological disposal of radioactive waste [1]. For safety assessments of radioactive waste repositories, amongst others, the sorption behavior of radionuclides onto the host rock has to be known. It is determined by various factors including pH, Eh, the presence of inorganic and organic ligands as well as the speciation of radionuclides in the aqueous and solid phase.
In the present work, the sorption of neptunium(V) onto granite and its main mineral constituents quartz, orthoclase, biotite, albite, and muscovite is studied under anaerobic conditions as a function of pH, ionic strength and solid/solution ratio in a series of batch equilibrium experiments. Furthermore, the effect of humic acid on the neptunium sorption is studied for different ligand concentrations. A 14C-labelled synthetic humic acid (type M42, [2]) is used for the experiments. Its sorption behavior is comparable to that of natural humic acids. The oxidation state of neptunium in the presence of humic acid and minerals is followed at selected pH values over a period of three months by NIR absorption spectroscopy. The neptunium sorption is affected by both the pH and the presence of organic material.
Neptunium species on the mineral surface are identified using neptunium LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The structural parameters of the near-neighbor surrounding of sorbed neptunium are compared to those of neptunium hydrate, hydroxide and humate complexes.

[1] Papp, R.: Gegenüberstellung von Endlagerkonzepten in Salz und Hartgestein. FZKA-PTE Nr. 3, Forschungszentrum Karlsruhe GmbH, Karlsruhe 1997.
[2] Bubner, M., et al.: Isotopically Labelled Humic Acids for Heavy Metal Complexation. J. Labelled Compounds and Radiopharmaceuticals XLI, 1017 (1998).
Keywords: Neptunium, humic acid, sorption, granite, muscovite, orthoclase, quartz, albite, biotite, EXAFS
  • Poster
    8th International Conference on Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere: Migration '01, Bregenz, Austria, 16.-21.09.2001

Permalink: https://www.hzdr.de/publications/Publ-3792
Publ.-Id: 3792


Benchmarking of DYN3D/RELAP5 Code Package using the Fifth AER Dynamic Problem for Coupled Codes

Kozmenkov, Y.; Orekhov, Y.; Grundmann, U.; Kliem, S.; Rohde, U.; Seidel, A.
The paper presents a brief description of the DYN3D/RELAP5 code package developed on the base of coupling the system code RELAP5 and the 3D neutron kinetics code DYN3D. Elaboration of the coupling interface has been performed in the framework of a joint research project.
The fifth dynamic AER problem for VVER-440 reactor plant has been solved using the code package. Calculation results are compared with the results obtained earlier in the FZR using DYN3D/ATHLET. Code-to-code comparison shows a close agreement between the key transient parameters.
  • Lecture (Conference)
    Tenth Symposium of AER on VVER Reactor Physics and Reactor Safety 2000, Moscow (Russia), 18.-22. September 2000, Proceedings pp. 1043-1048
  • Contribution to proceedings
    Tenth Symposium of AER on VVER Reactor Physics and Reactor Safety 2000, Moscow (Russia), 18.-22. September 2000, Proceedings pp. 1043-1048

Permalink: https://www.hzdr.de/publications/Publ-3791
Publ.-Id: 3791


On usage of coupled neutron-kinetic and thermal-hydraulic computer code DYN3D/ATHLET to study safety of VVER-1000 type reactors under transient and emergency operational modes

Rohde, U.; Kliem, S.; Seidel, A.; Khalimonchuk, V.; Kuchin, A.
Presently, increased requirements are imposed to study transient and emergency operation modes of nuclear facilities from point of view of quality and adequacy their simulation. In particular, concerning the Ukrainian NPP's this is connected with the analysis of VVER-1000 safety for a whole number of dsign basic accidents.
The first experience was obtained for the use of the coupled code DYN3D/ATHLET caculating a transient connected with the switching-off of one main coolant pump at the unit 6 of the Zaporizhya NPP.
  • Lecture (Conference)
    Tenth Symposium of AER on VVER Reactor Physics and Reactor Safety 2000, Moscow (Russia), 18.-22. September 2000, Proceedings pp. 913-920
  • Contribution to proceedings
    Tenth Symposium of AER on VVER Reactor Physics and Reactor Safety 2000, Moscow (Russia), 18.-22. September 2000, Proceedings pp. 913-920

Permalink: https://www.hzdr.de/publications/Publ-3790
Publ.-Id: 3790


Spin-density enhancement in a 119Sn implanted (110)Cr single crystal as evidenced by Mössbauer spectroscopy

Dubiel, S. M.; Cielak, J.; Zukrowski, J.; Reuther, H.
Magnetic properties of a presurface zone of the bulk, single-crystal (110)Cr, implanted with 119Sn ions were studied by means of conversion electron Mössbauer spectroscopy. A strong enhancement of the magnetic hyperfine field, B, was found. The increase is by a factor of ~2.7 in the average value of B and by a factor of ~2.3 in the most probable value of B (the amplitude of the spin-density waves, SDW's). The observed effects are explained in terms of the interference of two spin-density waves having the same amplitude phase but various polarizations. The relative contributions of the interfering SDW's was estimated as equal to ~60% for those with mutual perpendicular and ~40% for those with mutual parallel polarization.
  • Physical Review B 63 (2001) 060406(R)-1-4

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Permalink: https://www.hzdr.de/publications/Publ-3789
Publ.-Id: 3789


Synthesis, characterization and stability studies of some potential brains seeking agents-trialkyl (triaryl) siloxyalkyl(aryl)-thiolato-3-thiapentane-1,5-dithialato oxorhenium(V) complexes.

Abedin, Z.; Spies, H.
Neutral lipophilic silicon organic compound of oxorhenium complexes were obtained by the "3+1" mixed ligand approach with the simultaneous complexation of one SSS tridentate ligand and a monodentate S-R ligand with the formation of the oxorhenium(V) complexes. Four trialkyl(triaryl)siloxyalkane(benzene)thiolato-(3-thiapentane-1,5-dithiolato)oxorhenium complexes of the general formula (SCH2CH2SCH2CH2S) ReO (SQOSiR3) were synthesized and studied where
IV, Q = CH2CH2, R = CH2 CH3
V, Q = CH2CH2 CH2, R = CH2 CH3
VI, Q = C6H5, R = CH2CH3
VII, Q = CH2CH2, R = C6H5
Identification and determination of structure of the compounds (IV-VII) and hydrolized products (I-III) were carried out by TLC, HPLC, elemental analysis and IR, UV and NMR spectroscopic methods. Lipophilicity was determined by reverse phase HPLC method. As a role the more lipophilic compounds should have stronger binding with the C18 chain of the column material giving higher retention time. The retention time of the silicon rhenium complexes(IV-(VII) and the corresponding OH compounds (I-III) of the general formula (SCH2CH2SCH2CH2S)ReO(SQOH) where I, Q= CH2 CH2, II, Q= CH2CH2 CH2, R = III, Q=C6H5, were determined as

Compound.....Retention time (min)..............Compound.......Retention time (min)
I.....................2.60.....................................IV....................4.16
II....................2.64......................................V....................4.26
III...................2.87......................................VI....................4.46
I.....................2.60......................................VII.................. 4.93

It observed that the retention time of the compounds increases with the increase of lipophilicity as expected on the reverse phase column and the introduction of alkyl or arylsilyl radical to the oxygen atom greatly increases the lipophilicity. Stability of the silicon rhenium complexes (IV-VII) was studied in acetonitrile-water solution at different temperature and pH by reverse phase HPLC method. Of the four compounds triethylsiloxyalkylthiolato (IV and V) complexes were found to be the most stable with respect to both temperature and pH changes. Trialkylphenylsiloxy compound (VI) was found to be most unstable one. All the compounds were labile in acidic pH. The most lipophilic compound (VII) was less soluble in acetonitrile-water (1:1) system.
  • Lecture (Conference)
    VII. Asia and Oceania Congress of Nuclear Medicine and Biology and IV. International Congress of Nuclear Oncology, 1.-5-10.2000, Istanbul/Turkey
  • Abstract in refereed journal
    Turkish Journal of Nuclear Medicine 9 (2000) 92

Permalink: https://www.hzdr.de/publications/Publ-3787
Publ.-Id: 3787


Bubble Size Distributions and Radial Profiles in Vertical Pipe Flow

Lucas, D.; Krepper, E.; Prasser, H.-M.
The paper presents a method for the prediction of the radial gas fraction profile from a given total bubble size distribution. The method is based on the assumption of the equilibrium of the forces acting on a bubble perpendicularly to the flow direction. A large number of bubble classes is assumed. Based on the radial profile of the liquid velocity, radial distributions are calculated separately for all bubble classes. The resulting local bubble size distributions can be used by models for bubble coalescence and break-up. It is supposed, that the attempts for a one-dimensional modelling of bubble coalescence and break-up suffer in case of pipe flow from neglecting the radial profiles of the particle densities for the single bubble classes. The model is the basis of a fast running one-dimensional steady state computer code. The results of the model are compared with experimental data for a number of gas and liquid volume flow rates.
Keywords: Pipe flow, Two-phase flow, Flow regime
  • Poster
    3rd European Congress of Chemical Engineering, Nuremberg, 26 - 28 June, 2001, Conference-CD, File 532.htm; Abstract in Chemie Ingenieur Technik 73 (2001) 640
  • Contribution to proceedings
    3rd European Congress of Chemical Engineering, Nuremberg, 26 - 28 June, 2001, Conference-CD, File 532.htm; Abstract in Chemie Ingenieur Technik 73 (2001) 640

Permalink: https://www.hzdr.de/publications/Publ-3786
Publ.-Id: 3786


TEM-Untersuchungen an ionenstrahlmodifizierten Materialien

Mücklich, A.
  • Lecture (others)
    Ehrenkolloquium anläßlich des 65. Geburtstages von Prof. Dr.-Ing. habil. Peter Klimanek an der TU Bergakademie Freiberg am 26. Mai 2000

Permalink: https://www.hzdr.de/publications/Publ-3785
Publ.-Id: 3785


3-O-methyl-6[18F]Fluor-L-DOPA (OMFD) - First experiences in brain tumor imaging

Franke, W.-G.; Alheit, H.-D.; Beuthien-Baumann, B.; Bergmann, R.; Bredow, J.; Brust, P.; Burchert, W.; Füchtner, F.; Johannsen, B.; Kretzschmar, M.
F-18 labelled amino acid 3-O-methyl-6[18F]Fluor-L-DOPA (OMFD), not used for diagnostics until now, was synthesized, tested in cell cultures as well as in animals and studied in patients (pts) with recurrences of low differentiated brain tumors. Synthesis is based on a new precursor (N-formyl-3-O-methyl-4-O-Boc-6-trimethylstannyl-L-DOPA-ethyl-ester). Biologic behavior was tested HAT 29 and RBE-4-cell cultures and tumor bearing nude mice. First clinical studies we carried out in recurrent glioblastoma multiforme (4 pts.) with inconclusive MRT and CT. The application of OMFD was based on an individual decision. The aim was to detect localization and extent of recurrent tumor for planning of stereotactic radiotherapy. After 50 min synthesis time a radiochemical yield of 20 - 25% was reached. A high tracer uptake in tumor cells via L-amino-transporter was seen. However there was no evidence for metabolism or incorporation into proteins. Biodistribution in mice showed 60 min p.i. high intratumoral uptake (12.4 ± 1.8% ID/g) and a tumor/blood ratio of 9.5 ± 0.8. Increased radioactivity uptake was found in all pts. 60 min p.i. in the region of the suspected recurrences (lesion/nonlesion 2.2 ± 0.5), only little tracer uptake was found in the whole body scans in muscle, thorax and abdomen. Suspected recurrences were clearly seen in on PET images. Preliminary diagnostic studies in pts. With low differentiated tumor suggest that the new F-18 labelled amino acid is a valuable PET-tracer for tumor imaging.
Keywords: PET; F-18-OMFD; glioblastoma
  • Lecture (Conference)
    VII. Asia and Oceania Congress of Nuclear Medicine and Biology and IV. International Congress of Nuclear Oncology, 1.-5-10.2000, Istanbul/Turkey
  • Abstract in refereed journal
    Turkish Journal of Nuclear Medicine 9 (2000) 64

Permalink: https://www.hzdr.de/publications/Publ-3784
Publ.-Id: 3784


Studies in caffeine binding - The benefical role of aqueous media

Waldvogel, S. R.; Stephan, H.; Fröhlich, R.
  • Poster
    2. SFB-Symposium des SFB 452 "Functional Supramolecular Systems", 27.-28.10.2000, Ruhr-Universität Bochum

Permalink: https://www.hzdr.de/publications/Publ-3783
Publ.-Id: 3783


Comparison of [18F]FHPG and [124/125I]FIAU for imaging herpes simplex virus type 1 tymidine kinase gene expression

Brust, P.; Haubner, R.; Friedrich, A.; Scheunemann, M.; Anton, M.; Koufaki, O.-N.; Hauses, M.; Noll, S.; Noll, B.; Haberkorn, U.; Schackert, G.; Schackert, H. K.; Avril, N.; Johannsen, B.
Various radiotracers based on uracil nucleosides (e.g 2'-fluoro-2'-deoxy-5-[124I]iodo-1-beta-D-arabinofuranosyluracil, [124I]FIAU) and acycloguanosine derivatives (e.g. 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)methyl]guanine, [18F]FHPG) have been proposed as suitable substrates for the noninvasive imaging of herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene expression. However, for evaluation of these tracers different in vitro and in vivo models were used which did not permit a direct comparison of selectivity and affinity. Therefore, we directly compared [18F]FHPG and radioiodinated FIAU to assess their potential for PET imaging of transgene expression.
The uptake of [125I]FIAU, [18F]FHPG and [3H]acyclovir was determined in vitro using four different HSV1-tk expressing cell lines and their respective negative controls. The in vitro tracer uptake was generally low in nontransduced cell lines demonstrating low affinity to cellular thymidine kinases. In HSV1-tk expressing cells, [3H]acyclovir showed approximately a 2-fold higher tracer accumulation, the [18F]FHPG uptake increased to approximately 6-fold and the [125I]FIAU accumulation to approximately 28-fold after 120 min incubation of T1115 human glioblastoma cells. Similar results were found in the other cell lines. In addition, biodistribution and PET studies with [18F]FHPG and [124/125I]FIAU were carried out in tumour-bearing BALB/c mice. Significantly higher specific tracer accumulation was found for [125I]FIAU compared to [18F]FHPG. The ratio of specific tracer accumulation between [125I]FIAU and [18F]FHPG increased from 21 (30 min p.i.) to 119 (4 hours p.i.). PET imaging, using [124I]FIAU, clearly visualised and delineated HSV1-tk expressing tumours, whereas only a negligible uptake of [18F]FHPG was observed.
This study demonstrated that in vitro and in vivo, the radioiodine labelled uracil nucleoside FIAU has a significantly higher specific accumulation than the acycloguanosine derivative [18F]FHPG. This suggests that [124I]FIAU should be the preferred reporter probe for PET imaging of HSV1-tk gene expression. However, the use of [124I]FIAU is hampered by the relatively long physical half-life, the low positron emission and the limited availability of the radionuclide. Thus, further attempts to develop suitable PET tracers for the assessment of HSV1-tk gene expression should also focus on 18F-labelled uracil derivatives.

Keywords: Gene therapy; FHPG; FIAU; HSV-1 thymidin kinase; PET
  • European Journal of Nuclear Medicine Vol.28, No. 6, (2001) 721-729

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Publ.-Id: 3782


Experimental and numerical investigation of one and two phase natural convection in storage tanks

Krepper, E.; Aszodi, A.; Prasser, H.-M.
Experiments were performed to investigate heating up processes of fluids in storage tanks under the influence of an external heat source. As a consequence of an external fire, the heat-up of the inventory may lead to the evaporation of the liquid and to release of significant quantities of dangerous gases into the environment. Heating the vessel from the side walls, a strong temperature stratification is observed leading to large temperature gradients. At the top of the tank evaporation can start much earlier than the average temperature reaches saturation.
Several tests were performed both with heating from the bottom and with heating from the side walls. The test tank was equipped with thermocouples and with needle probes for measuring of the local void fraction.
In the FZ-Rossendorf calculations were performed using the CFD-code CFX-4. The simulation comprises two phase flow, subcooled boiling at the heated wall and steam release at the tank surface. The paper presents comparisons of measured and calculated temperatures and void fractions. The comparison allows, to test the used models, to clarify weak points of the models and to identify directions of further development of modelling boiling and two phase flow.
Keywords: heat transfer, boiling, single phase natural convestion, two phase flow, experiments, computational fluid dynamics calculations
  • Lecture (Conference)
    4th International Conference on Multiphase Flow, New Orleans, Lousiana, USA - May 27 to June 1, 2001, Conference-CD, Paper 515
  • Contribution to proceedings
    4th International Conference on Multiphase Flow, New Orleans, Lousiana, USA - May 27 to June 1, 2001, Conference-CD, Paper 515

Permalink: https://www.hzdr.de/publications/Publ-3781
Publ.-Id: 3781


Nutzung erneuerbarer Energien zur Stromerzeugung in den neuen Bundesländern

Rindelhardt, U.
Schwerpunkte:

- Technische und wirtschaftliche Entwicklungen im letzten Jahrzehnt
- Derzeitige Beiträge der einzelnen erneuerbaren Energien
- Wirtschaftlichkeit unter den aktuellen Rahmenbedingungen
- Mittelfristige Perspektiven der Nutzung erneuerbarer Energien in der Stromerzeugung
  • Lecture (Conference)
    3. Energietechnisches Kolloquium der BTU Cottbus, 6.9.2001, in: BTU Forschungshefte Energie(Hrg. B. Schieferdecker, Ch. Fünfgeld): Energietag Brandenburg 2001, Beitrag 12
  • Contribution to external collection
    3. Energietechnisches Kolloquium der BTU Cottbus, 6.9.2001, in: BTU Forschungshefte Energie(Hrg. B. Schieferdecker, Ch. Fünfgeld): Energietag Brandenburg 2001, Beitrag 12

Permalink: https://www.hzdr.de/publications/Publ-3780
Publ.-Id: 3780


Validation of Coupled Codes for VVER Reactors by Analysis of Plant Transients

Mittag, S.; Kliem, S.; Weiß, F.-P.; Kyrki-Rajamäki, R.; Hämäläinen, A.; Langenbuch, S.; Danilin, S.; Hadek, J.; Hegyi, G.; Kuchin, A.; Panayotov, D.
Three-dimensional hexagonal reactor dynamic codes have been developed for VVER type reactors and coupled with different thermal
hydraulic system codes. In the EU Phare project SRR1/95 these codes have been validated against collected real plant transients by the participants from 7 countries. The two experiments chosen for calculation were such that both primary circuit behaviour and fission power behaviour were strongly affected including movements of control rods. Critical boron concentrations, 3-D core power distributions, time behaviour of fission power, coolant temperatures and pressures were the main parameters utilised in the validation. Good accuracy of the results was generally achieved comparable to the measurement accuracy. Confidence in the results of the different code systems has increased and the consequences of certain model changes could be evaluated.
  • Lecture (Conference)
    Tagungsband der Fachtagung der KTG: "Wechselwirkungen Neutronenphysik und Thermofluiddynamik", pp. 4-55 bis 4-66, Forschungszentrum Rossendorf, 31. Januar - 1. Februar 2000
  • Contribution to proceedings
    Tagungsband der Fachtagung der KTG: "Wechselwirkungen Neutronenphysik und Thermofluiddynamik", pp. 4-55 bis 4-66, Forschungszentrum Rossendorf, 31. Januar - 1. Februar 2000

Permalink: https://www.hzdr.de/publications/Publ-3778
Publ.-Id: 3778


Development and Benchmarking of the DYN3D/RELAP5 Code System

Kozmenkov, Y.; Orekhov, Y.; Grundmann, U.; Kliem, S.; Rohde, U.; Seidel, A.
The integration of advanced computer codes from different safety analysis areas into code systems of expanded modeling capabilities results in a more detailed and accurate representation of reactor plant structural components. Less conservative predictions of advanced codes are needed to analyse the transients of LWRs. As a result of the joint FZR-IPPE research project, the coupled code system DYN3D/RELAP5 has been developed. The incorporation of the DYN3D spatial kinetics model into the RELAP5 code overcomes the restrictions of the stand-alone codes. AER-5 benchmark calculations for the VVER-440 reactor plant have been performed to validate the code. Code-to-code comparison (DYN3D/RELAP5-DYN3D/ATHLET) of simulation results shows a good agreement and confirm a validity of the developed internally coupled code system.
Keywords: nuclear reactors system codes three-dimensional core model coupled code safety analysis benchmarks
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2001, Dresden, 15 - 17 Mai 2001, Tagungsbericht S. 15 - 18.
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2001, Dresden, 15 - 17 Mai 2001, Tagungsbericht S. 15 - 18.

Permalink: https://www.hzdr.de/publications/Publ-3775
Publ.-Id: 3775


X-ray waveguides with multiple guiding layers

Pfeiffer, F.; Salditt, T.; Hoghoj, P.; Anderson, I.; Schell, N.
We have generalized the principle of resonant x-ray beam coupling to waveguiedes containing multiple guiding layers and characterised their x-ray optical properties. By measuring the farfield pattern formed by the interference of the beams, we demonstrate the possibility of using these devices as new tools to tailor the field distribution in the near- and far-field region for specific applications.
Keywords: x-ray waveguides: multiple layered structure; x-ray beam conditioning
  • Phys. Rev. B 62 (2000) 16939-16943

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Publ.-Id: 3774


Si/Ge-nanocrystals in SiC(0001)

Heß, G.; Bauer, A.; Kräußlich, J.; Fissel, A.; Schröter, B.; Richter, W.; Schell, N.; Matz, W.; Goetz, K.
Different SiC-surfaces were coated with thin layers of Si or Ge and subsequently annealed to 900 °C respective 600 °C. According to AFM results, Si- or Ge-clusters, respectively, are formed whose number, size distribution and shape depend on the process parameters. Such samples were investigated with synchrotron x-ray diffraction on the ROBL-beamline at the ESRF. The /2 - scans show for all samples (111)- and (220)-reflections of Si or Ge, respectively. This reveals unambiguously that the clusters grow preferentially in two different orientations (<111>, <110>). Interestingly, for the Ge-samples those reflections are shifted towards the angular position of the corresponding Si-reflection. Such a peak shift could be explained by a lattice distortion due to the lattice mismatch or by the change in the lattice constant due to the formation of a Si/Ge solid solution. The lateral orientation of the (111)- and (110)-clusters was investigated by comparison of the -scans of a cluster-reflection (220-reflection for (111)-clusters and 111-reflection for (110)-clusters) with an appropriate substrate-reflection. This comparison showed that the (111)-clusters as well as the (110)-clusters grow coherently with respect to the substrate.
Keywords: Si/Ge-nanocrystals; SiC; X-ray diffraction
  • Thin Solid Films 380 (2000) 86-88

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Publ.-Id: 3773


A two magnetron sputter deposition chamber for in situ observation of thin film growth by synchrotron radiation scattering

Matz, W.; Schell, N.; Neumann, W.; Bøttiger, J.; Chevallier, J.
The design of a sputter deposition chamber for the in situ study of film growth by synchrotron x-ray diffraction and reflectivity is reported. Four x-ray windows, sealed with low cost, non-hazardous Kapton, enable scattering both in the horizontal as well as in the vertical scattering planes. The chamber fits into a standard six-circle goniometer from Huber which is relatively widespread in synchrotron laboratories. Two miniature magnetrons and additional gas inlets allow for the deposition of compound films or multilayers. Substrate heating up to 650°C and different substrate bias voltage are possible. The performance of the chamber was tested with the deposition of high quality TiN films of different thicknesses.
Keywords: X-ray diffraction; in-situ investigations; sputter deposition; film growth
  • Review of Scientific Instruments Vol 72, Number 8 (2001) 3344-3348

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Publ.-Id: 3772


Synthetische Huminsäuren und ihre Anwendung zur Untersuchung des Radionuklidtransports in der Umwelt

Sachs, S.; Bubner, M.; Schmeide, K.; Heise, K. H.; Bernhard, G.
Die realitätsnahe Beschreibung der Wechselwirkung von Actiniden mit Huminsäuren sowie des Migrationsverhaltens von Actiniden in Gegenwart von Huminsäuren ist unerläßlich für zuverlässige Prognosen zur Ausbreitung von Actiniden in natürlichen Aquifersystemen. Da natürliche Huminsäuren jedoch in Abhängigkeit von ihrer Herkunft unterschiedliche strukturelle und funktionelle Eigenschaften zeigen, ergeben sich Schwierigkeiten bei der Beschreibung ihres chemischen Verhaltens. Zur Erlangung detaillierterer Kenntnisse über die Wechselwirkung von Huminsäuren mit Actiniden wurden verschiedenartige Huminsäuremodellverbindungen mit definierten chemischen Eigenschaften entsprechend dem Melanoidinkonzept entwickelt und hinsichtlich ihrer Eignung als Funktionalitätsmodelle für Huminsäuren untersucht [1]. Darüber hinaus wurden Verfahren zur Synthese von 14C-markierten Huminsäuren mit stabiler Markierung des Molekülgerüsts entwickelt [2], die aufgrund ihrer sehr empfindlichen Nachweisbarkeit in niedrigen Konzentrationsbereichen in Migrationsexperimenten, z.B. zur Untersuchung kinetischer Prozesse [3], einsetzbar sind.
Die vorliegende Arbeit demonstriert am Beispiel der synthetischen Huminsäure vom Typ M42, die mit natürlichen Huminsäuren vergleichbare Carboxylgruppenzahlen hat, die Synthese, die 14C-Markierung und die Modifizierung der Huminsäurefunktionalität als auch deren Einsatz in Komplexierungs- und Sorptionsexperimenten. Die unter Verwendung dieser Huminsäure erzielten Ergebnisse zur Untersuchung der Wechselwirkung von Huminsäuren mit Neptunium(V) werden vorgestellt. Dazu gehören auch Untersuchungen zum Einfluß phenolischer und anderer acider Gruppen auf das Komplexbildungsverhalten von Huminsäuren gegenüber Neptunium(V) im neutralen pH-Bereich. Der Vorteil der Radiotracertechnik durch Einsatz der 14C-markierten Huminsäure vom Typ M42 in Sorptionsexperimenten wird am Beispiel der Neptunium-Sorption an Granit in Gegenwart von Huminsäuren gezeigt.
Erste Ergebnisse zur Synthese von Huminsäuren mit ausgeprägt reduzierenden Eigenschaften werden dargestellt. Diese sollen zur Untersuchung von Redoxvorgängen bei der Wechselwirkung von Huminsäuren mit Actinidionen Einsatz finden.

[1] Pompe, S., Bubner, M., Schmeide, K., Heise, K.H., Bernhard, G., Nitsche, H.: Influence of Humic Acids on the Migration Behavior of Radioactive and Non-Radioactive Substances under Conditions Close to Nature. Synthesis, Radiometric Determination of Functional Groups, Complexation. Report FZR-290, Rossendorf 2000.
[2] Bubner, M., Pompe, S., Meyer, M., Heise, K.H., Nitsche, H.: Isotopically Labelled Humic Acids for Heavy Metal Complexation. J. Labelled Cpd. Radiopharm. XLI, 1057 (1998).
[3] Schmeide, K., Brendler, V., Pompe, S., Bubner, M., Heise, K.H., Bernhard, G.: Kinetic Studies of the Uranium(VI) and Humic Acid Sorption onto Phyllite, Ferrihydrite and Muscovite. In: Report FZKA 6524 (G. Buckau, ed.), Karlsruhe 2000, S. 149-169.
Keywords: Huminsäuren, Modellverbindungen, Synthese, Markierung, Modifizierung, Komplexierung, Neptunium, Sorption
  • Poster
    GDCh-Jahrestagung Chemie 2001, Fachgruppe Nuklearchemie, 24.-26.09.2001, Würzburg

Permalink: https://www.hzdr.de/publications/Publ-3767
Publ.-Id: 3767


Uranyl(VI) complexes with alpha-substituted carboxylic acids in aqueous solution

Moll, H.; Geipel, G.; Reich, T.; Bernhard, G.; Fanghänel, T.; Grenthe, I.
Alpha substituted carboxylic acids are present as degradation products of wood in nature and in repositories for low-level radioactive waste. Such substances find extensive application in separation processes of various types, i.e., group separations of 4f and 5f elements. Their interaction with radionuclides was investigated in the pH range 3 to 5 mainly by potentiometry and NMR techniques. Whereas information on their structural and spectroscopic properties are rare.

The complex formation in the binary uranium(VI)-glycolate, -alpha-hydoxyisobutyrate, -alpha-aminoisobutyrate systems in 1.0 M NaClO4 medium was investigated by means of UV-vis and TRLFS. From spectroscopic investigations by UV-vis, single component absorption spectra are suggested and extinction coefficients calculated. An increase in absorption and a red shift of the spectra, 5 nm compared to the free UO22+, are indicating the interaction of UO22+ and a-substituted carboxylic acids already at pH 2. 1:1 complexes are dominating the uranyl speciation in the glycolate, alpha-hydoxyisobutyrate, and alpha-aminoisobutyrate system at pH 2 and 3, respectively. The formation constant of the 1:2 complex of uranyl with alpha-aminoisobutyric acid is reported for the first time at pH 4. A variety of techniques, such as XRD, XAS, TRLFS, and IR, were applied to explore the structure of the main species in solution and in solid state.

This work was supported by the European Union under contract number: HPMF-CT-1999-00342.

Keywords: Uranium(VI), Complex formation, Alpha-substituted carboxylic acids
  • Lecture (Conference)
    MIGRATION '01, 8th International Conference on Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere Bregenz, Austria September 16 - 21, 2001
  • Radiochimica Acta 91, 11-20 (2003)

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Publ.-Id: 3763


Structure of high-spin states in 89Sr and 90Sr

Stefanova, E. A.; Schwengner, R.; Rainovski, G.; Schilling, K.-D.; Wagner, A.; Dönau, F.; Galindo, E.; Jungclaus, A.; Lieb, K. P.; Thelen, O.; Eberth, J.; Napoli, D. R.; de Angelis, G.; Axiotis, M.; Marginean, N.; Martinez, T.; Ur, C. A.; Kröll, T.; Gadea, A.; Kutsarova, T.

High-spin states of 89Sr and 90Sr were studied via the reactions 82Se(11B,p4n) and 82Se(11B ,p3n), respectively, at a beam energy of 37 MeV. Gamma rays were detected with the GASP spectrometer. The level schemes of 89Sr and 90Sr were extended up to E ≈ 8 MeV and E ≈ 10 MeV, respectively. The level structures in 89Sr and 90Sr were interpreted in terms of the spherical shell model. The calculations were performed in the configuration space (0f5/2, 1p3/2, 1p1/2, 0g9/2) f or the protons and (1p1/2, 0g9/2, 1d5/2) for the neutrons. High-spin level sequences in 89Sr are characterized by coupling the unpaired d5/2 neutron to proton excitations of the core nucleus 88Sr. An equidistant level sequence with ΔJ = 2 found in 90Sr is well described by the configuration π[(0f5/2-2) (0g9/22)] ν(1d5/22) which favors even spins.
Keywords: Nuclear structure, in-beam gamma-ray spectroscopy, shell-model calculations

  • Physical Review C, Vol. 63, 064315-1 - 10

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Publ.-Id: 3751


TransRay - ein dreidimensionaler Zellcode auf der Grundlage der Ray-Tracing Technik

Beckert, C.
Es wurde ein Zellcode (TransRay) entwickelt, der mit Hilfe der Ray-Tracing Technik die dreidimensionale Neutronenflußverteilung berechnet. Ziel war es dabei unter anderem, für dreidimensionale Probleme gemittelte makroskopische Wirkungsquerschnitte zu ermitteln. Als Anwendungsbeispiel werden in dieser Arbeit zwei Fälle betrachtet, der teilweise eingetauchte Regelstab und Void um einen Brennstab als Modell für eine Dampfblase im Moderatorgebiet. Hierfür mußte die Ray-Tracing Methode auf Gebiete mit Void erweitert werden. Das häufig verwendete kommerzielle Programm HELIOS berechnet die gemittelten Wirkungsquerschnitte nur zweidimensional. Für eine bestimmte Eintauchtiefe des Regelstabes muß daher zum Beispiel zwischen den berechneten Werten des vollständig eingetauchten und des gezogenen Regelstabes interpoliert werden. In diesem Artikel wird zunächst die Theorie erläutert und anschließend werden Ergebnisse für die beiden oben erwähnten Fälle am Beispiel der Kernkonfiguration eines Leichtwasserreaktors gezeigt und kurz diskutiert.
Keywords: Ray Tracing Zellcode gemittelte Wirkungsquerschnitte Leichtwasserreaktor Void dreidimensional 3D Transportgleichung Eigenwert Neutronen Neutronenfluß Stoßwahrscheinlichkeiten Zellrechnung
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2001, Dresden, 15.-17. Mai 2001, Tagungsbericht S. 51-54
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2001, Dresden, 15.-17. Mai 2001, Tagungsbericht S. 51-54

Permalink: https://www.hzdr.de/publications/Publ-3750
Publ.-Id: 3750


Die Dynamik von Strahlenschäden durch fokussierte Ionenstrahlen am Beispiel der Ionenstrahlsynthese

Hausmann, S.
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-313 Januar 2001

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Permalink: https://www.hzdr.de/publications/Publ-3749
Publ.-Id: 3749


Liquid metal ion source-produced germanium ions for maskless ion implantation

Ganetsos, T.; Aidinis, C.; Bischoff, L.; Mair, G. L. R.; Teichert, J.; Panknin, D.; Popadopoulos, I.
We report on a prelimery investigation on the maskless implantation of Ge ions into Si for the production of Si 1-x Gex microstructures. The technique employs a focused ion beam system using a liquid metal alloy ion source. Closely spaced simple structures down to about 1 µm in width, with well-defined boundaries, have been produced. On some of these structures, spreading resistance measruements were carried out.
Keywords: Si 1-x Gex microstructures, focused ion beam
  • Journal of Physics D: Appl. Phys. 34 (2001) L 11 - L13

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A study of the temperature dependence of the energy spread and energy deficit of a Ge ++ ion beam produced by a liquid metal alloy ion source

Aidinis, C. J.; Mair, G. L. R.; Bischoff, L.; Papadopoulos, I.
This work involves an extensive study of the dependence on temperature (T) of the energy spread Delta E 1/2 and the potential energy deficit of the energy distribution of the Ge ++ beam produced by a liquid metal alloy ion source. The liquid metal alloy is Au77Ge14Si9. Differnces between consecutive sets of measurements were found but the energy spread versus temperature measurements agree remarkably well with a recent model that predicts Delta E 1/2 ~ T 1/2 . However, some questions involving the results either remain unsolved or are tentatively answered.
Keywords: Liquid metal alloy ion source, energy stread, energy deficit, temperature dependence
  • Journal of Physics D: Appl. Phys. 34 (2001) L14 - L 16

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Alloying of silicon on Ti6Al4V using high-intensity pulsed plasma beams

Richter, E.; Piekoszewski, J.; Prokert, F.; Stanislawski, J.; Walis, L.; Wieser, E.
Tianium and his alloys are widely used in medical applications, e.g. for artifical joints, dental prosthesis, teeth and so on. However, it these metals have to be coated with ceramic facing, some stability problems in the ceramic-titanium system arise due to the strong affinity of titanium to oxygen, which causes a reduction of the ceramic oxide. It is known that this reduction effect can be mitigated by alloying titanium or its alloys with a small amount of silicon using, e.g. an ion implantation technique. In the present work, we report the results of a new approach to alloying silicon to Ti6Al4V using high intensity pulsed plasma beams. The feasibility to from the silicide Ti5Si3 with grain size larger as 75 nm is demonstrated. This silicide has the highest melting point (2130 °C) among of all stable phases in the Si-Ti system.


Keywords: pulsed plasma beams, surface treatment, slicides
  • Vacuum 63 (2001) 523-527

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Alloying of Pd into Ti by Pulsed Plasma Beams

Werner, Z.; Piekoszewski, J.; Barcz, A.; Grötzschel, R.; Prokert, F.; Stanislawski, J.; Szymczyk, W.
Pd-Ti alloy surface layers in Ti formed by N- and Ar-plasma alloying of Pd films deposited by pulse erosion of Pd electrode tips were studied by RBS, XRD, SIMS, and gravimetric analysis. Layers of a thickness up to 2 µm and concentration up to 40% Pd at the surface were obtained. Pd is present as a solute in hcp alpha-Ti and as TiPd and TiPd3 phases. The Pd profiles follow gaussian distribution although no simple theoretical model can account for this behaviour.
Keywords: pulse plasma treatment, surface alloys, corrosion protection
  • Nuclear Instruments and Methods in Physics Research B 175-177 (2001) 767-771

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Influence of the process parameters on the properties of hydrogenated amorphous carbon thin films deposited using ECR plasma

Piazza, F.; Arnal, Y.; Grambole, D.; Herrmann, F.; Kildemo, M.; Lacoste, A.; Relihan, G.; Golanski, A.
A uniformly distributed multipolar microwave plasma reactor using electron cyclotron resonance at 2.45 GHz (600 W) was used to deposit a-C:H thin films at RT. C2H2 was used as precursor gas. Single crystal <100> Si and CR39 allelic resin substrates were RF biased to a negative voltage within the range between -10 and -200 V. The influence of the process parameters (gas flow and substrate bias) on the growth rate and hydrogen content have been investigated in detail. Optical parameters (optical gap ET, index of refraction n and extinction coefficient k) were measured using spectroscopic ellipsometry. The resonant (6.385 MeV) nuclear reaction: 1H(15N, alpha gamma)12C was used to determine the hydrogen content. For the C2H2 pressure range of 0.6 < P( C2H2) < 1.1 mTorr the optical parameters remain constant within the limits of experimental uncertainty. The sp3 content is seen to vary monotonically as a function of pressure and to be reaching a maximum of about 40% for 0.6 < P( C2H2) < 0.7 mTorr. The variation of the substrate bias within the range from -10 V to -190 V (at P( C2H2) = 0.6 mTorr) has no measurable impact neither on the deposition rate nor on the hydrogen content. The corresponding average values of ET and n remain stable (ET = 1.83 ± 0.11 eV, n = 2.12 ± 0.04). However, an increase in the bias is followed by a significant decrease of the extinction coefficient k and of the absorption tail width E0 . The observed evolution of k and E0 suggests that the sp2 clustering mode may be related to the substrate bias.

Keywords: carbon, thin films, hard coatings, optical properties, plasma processing
  • Poster
    EMRS'2000, 30. May - 2. June 2000, Strasbourg, France
  • Thin Solid Films 383(2001), 196-199

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Thermodynamik der Wasserstoffabsorption in BaZr0.85 Y0.15O2.925/H2O

Groß, B.; Beck, C.; Engeldinger, J.; Grambole, D.; Herrmann, F.; Hempelmann, R.
Dünne Schichten des Protonenleiters BaZr0.85 Y0.15O2.925/H2O (BZY15) wurden durch mehrfache Tauchbeschichtung mit einer mittleren Dicke von 900 nm hergestellt. Weiterhin wurden mikrokristalline und Nano-Pulver, mit Teilchengrößen zwischen 8 nm und 20 nm, präpariert.
Film- und mikrokristalline Proben wurden mit Wasserstoff, durch dissoziative Wasserdampfabsorption unter definierten Bedingungen, beladen. Die absoluten Wasserstoffkonzentrationen wurden mit der kernphysikalischen 15N Ionenstrahltechnik bestimmt. Mit einem Zweizustandsmodell, basierend auf Fermi-Dirak-Statistik, wurden die thermodynamischen Daten der Wasserdampfabsorption bestimmt [1].
Durch impedanzspektroskopische Messungen an gepressten und gesinterten mikrokristallinen Pulvern konnte die Bulkleitfähigkeit ermittelt werden. Aus der Kombination der Leitfähigkeit, den absoluten Protonenkonzentrationen und den protonischen Transportzahlen, bestimmt in Konzentrationszellenexperimenten, konnte der Leitfähigkeits-Diffusionskoeffizient des Bulkmaterials berechnet werden.
Weitere impedanzspektroskopische Messungen wurden an größenkontrolliert hergestellten Nano-Pulvern durchgeführt, um den Einfluss der Kristallgröße auf die protonische Leitfähigkeit zu ermitteln [2].

Literatur:
[1] B. Groß, J. Engeldinger, D. Grambole, F. Herrmann und R. Hempelmann,
Phys. Chem. Chem. Phys. 2 (2000) 297-301
[2] Ch. Beck, W. Härtl und R. Hempelmann,
J. Mater. Res. 13 (1998) 3174
  • Lecture (Conference)
    99. Hauptversammlung der Deutschen Bunsengesellschaft für Phys. Chemie, 1. - 3. Juni 2000, Würzburg

Permalink: https://www.hzdr.de/publications/Publ-3738
Publ.-Id: 3738


Application of new materials for integrated low-energy ignition elements in airbag systems - characterization and simulation

Weiß, U.; Löbner, T.; Geßner, T.; Hoyer, W.; Grambole, D.
The direction of current research activities by international producers of ignition elements for airbag systems is developing cheap elements which are possible to be integrated into an ignition microsystem. These integrated ignition element is the most important actuator in the whole airbag system.
In conformity with the integration of ignitor structure and electronic parts Si became the basic material. Related materials were selected for functional coatings.
The investigations involved preparation, characterization, testing, simulation and reliability of the functional coatings for ignition structures.
Poly-Si was used as reference material to compare our results with the literature. Furthermore hydrides of titanium, zirconium and hafnium were investigated. Optimaly conversions of the metallic coatings (deposited by sputtering) after a heat treatment in a hydrogen atmosphere could be observed by X-Ray Diffraction and the nuclearphysical 15N-method (Figure 1).
After a heat treatment (110°C, on air) the evaluation of stability over the time was performed by analysing the sheet resistance for TiHx- and HfHx - probes. The divergence of the resistance values related to the start value (without heat treatment) amounts 5% for TiHx and 1% for HfHx. Accordingly to /1/ the thermal stability of the metal hydrides increases from Ti to Hf.
To obtain suitable design parameters for the ignition elements, a coupled electrical and thermal simulation was performed by the commercial ANSYS FEM program.
Figure 2 shows an example of the good agreement between the curves of the simulated thermal behavior and the measured current.


/1/ Streb, Wasserstoff in den Metallen Titan, Zircon und Hafnium, Thesis, Frankfurt am Main, 1984
/2/ Weiß U., Löbner B., Abschlußbericht SIFA-MST, "Schneller Anzünder", Januar 1999
/3/ Weiß U., Dünnschichtanzündelement für pyrotechnische Wirkmassen, Patent DE 19721929
  • Lecture (Conference)
    3rd Int. Conf. and Poster Exhibition Micro Materials (MicroMat 2000), 17. - 19. April 2000, Berlin, Germany

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Publ.-Id: 3736


Lattice destruction during micro-channeling measurements

Herrmann, F.; Grambole, D.; Grötzschel, R.
The degree of postimplantation damage in various semiconductor crystals depends on the dose rate applied. In particular strong effects have been observed at dose rates up to 1019 cm-2s-1 which are typical for focused ion beam (FIB) devices with sub-µm beam diameters. For a systematic study of such damages a nuclear microprobe must be employed for RBS/channeling measurements. But the fluence of the analysing beam of light ions is here orders of degree higher than usually in RBS/C experiments. Therefore the damage generation by the analysing beam must be considered.
We have studied the near-surface damage accumulation at room temperature in 6H-SiC by H, He and Li ions of various energies both for channeling and random incidence.
The fluence dependence of the regular damage, observed with beams in the MeV region, is much smaller than that with low and medium energies. The damage level observed by RBS/C seems to saturate at a cmin value far below unity. The calculated ratios of Rutherford cross section to deposited nuclear energy [SRIM 2000] for H, He, and Li ions predict lowest damage per backscattering yield for H ions at the lower energy end. But in the case of µm beam dimensions the lattice damage by the proton beam due to swelling, bubble formation, precipitation etc. exceeds by far the regular ballistic disorder and is higher than in the case of He or Li ions of the same energy.
  • Poster
    7th Intern. Conference on Nuclear Microprobe Technology and Applications, Bordeaux, France, Sept. 2000

Permalink: https://www.hzdr.de/publications/Publ-3733
Publ.-Id: 3733


Optical properties of ta-C:H films deposited by ECR plasma using acetylene as precursor gas

Piazza, F.; Arnal, Y.; Lacoste, A.; Relihan, G.; Kildemo, M.; Grambole, D.; Herrmann, F.; Golanski, A.
A uniformly Distributed Multipolar Microwave plasma reactor using Electron Cyclotron Resonance at 2.45 GHz was used to deposit ta-C:H (DLC) films on silicon substrates at RT. The influence of the acetylene initial pressure (0.3 - 1.1 mTorr) and of the substrate bias (from -10 V to -190 V) on the DLC growth and structure has been investigated using spectroscopic ellipsometry. It is shown that the maximum sp3 content of about 40% (atomic) may be reached for the acetylene pressure of 0.6 - 0.7 mTorr. It is also shown that although the bias voltage has no measurable impact on the optical gap it has a significant influence on the extinction coefficient and the behaviour of the absorption tails. The results suggest that the sp2 clustering mode and the sp2 cluster size distribution are bias controlled.
  • Poster
    7th International Symposium on Trends and Applications of Thin Films (TATF' 2000), 27.-30.03.2000, Nancy, France
  • Contribution to proceedings
    7th Int. Symp. on Trends and Appl. of Thin Films (TATF' 2000), 27.-30.03.2000, Nancy, France
    Proceedings of TATF' 2000, 376-378

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Publ.-Id: 3732


Phase analysis in alpha-Fe after high-dose Si ion implantation by depth-selective conversion-electron Mössbauer spectroscopy (DCEMS)

Walterfang, M.; Kruijer, S.; Dobler, M.; Reuther, H.; Keune, W.
Si+ ions of 50 keV in energy were implanted into a-Fe (95% 57Fe) with a nominal dose of 5x10E17 cmE-2.
  • Hyperfine Interactions 126 (2000) 219-222

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Studies of carbon ion self-implantation into hydrogenated amorphous carbon films

Khan, R. U. A.; Grambole, D.; Silva, S. R. P.
The properties of polymer-like amorphous hydrogenated carbon thin films with low defect density have been studied. These films were implanted with carbon ions with a dose range of 1012 - 1016 cm-2. The purpose of the study is to investigate the effects of ion beam damage on this type of film. Optical absorption measurements observe a narrowing of the optical band gap, suggesting the introduction of a large number of defect states subsequent to the implantation resulting in the broadening of the band tails, only after a threshold ion dose of 1015 cm-2. Nuclear reaction analysis suggests also a reduction in the hydrogen content of the film which coincides with film thinning.


Keywords: Amorphous carbon; Defect; Hydrogen; Ion implantation
  • Diamand and Related Materials 9 (2000) 657 - 679

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Reliable micro-measurement of strontium is the key to cracking the life-history code in the fish otolith

Markwitz, A.; Grambole, D.; Herrmann, F.; Trompetter, W. J.; Dioses, T.; Gauldie, R. W.
The fish otolith is a calcium carbonate (usually aragonite) crystal that crows continuously by accretion over the life of the fish and unlike bone is not continuously re-metabolised. Consequently, the otolith has long been regarded as a potential store of information about the life history of an individual fish, and this information is encoded in the deposition pattern of trace elements in the otolith. The code has been difficult to crack. However, recent developments have show that: (1) Sr is one of the few non-mobile trace elements in the otolith; and (2) the pattern of Sr deposition summarises the effects of environment changes that affect the growth rate of the otolith crystal. The remaining difficulties in cracking the chemical code in the otolith have hinged about making reliable micro-measurements of the stable Sr content at spatial resolutions of 10 µm or less; this interval represents about 4-6 days of otolith growth in most species of fish. This paper describes high beam resolution 2 µm linear measurements, and 6 µm square measurements over narrow windows of about 300µm square, and links these micro-measures to macro-measures of 2D maps of the entire surface of sections of otoliths up to 5 mm square at beam resolutions of 25 µm square. The otoliths used in this study are from the Jurel, or Peruvian Jack mackerel, Trachurus murphyi (Carangidae: Teleostei).

Keywords: Nuclear microprobe; Elemental mapping; Sr measurements; Fish otoliths; Environmental; Trachurus murphyi PACS classification codes: 07.78.+s; 61.72.Ss; 89.60.+x
  • Nuclear Instruments and Methods in Physics Research B 168 (2000) 109-116

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The surface grating on GaAs(001) characterized by conventional and synchrotron X-ray methods

Mazur, K.; Sass, J.; Eichhorn, F.; Turos, A.
The investigation by means of triple crystal X-ray diffractometry and synchrotron reflectivity measurements were performed in two different kinds of laterally structured samples: (i) the simple surface grating created by photolithography methods (the surface grating were of the same material as the substrate) and (ii) stepped surface created by the intentionally off-oriented surface. The X-ray triple crystal arrangement allows us to measure reciprocal space maps of the scattered intensity, separating the intensity contributions of the scattered truncation rods on the first kind of samples. The synchrotron non-specular reflectivity measurements at ESRF were essential for proving the existence of stepped surfaces and examination of their structure.
Keywords: GaAs, high-resolution X-ray diffraction, X-ray reflectivity, surface grating, reciprocal space map
  • Lecture (Conference)
    XVIII Conference on Applied Crystallography, September 4 - 7, 2000, Wisła (Poland)
  • Lecture (Conference)
    Vortrag (Konferenzbeitrag): XVIII Conference on Applied Crystallography, September 4 - 7, 2000, Wisła (Poland)

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Publ.-Id: 3727


Laterally structured surfaces of GaAs(001) characterized by conventional and synchrotron X-ray methods

Mazur, K.; Sass, J.; Eichhorn, F.; Turos, A.
The samples with different laterally structured surfaces were investigated by means of triple crystal X-ray diffractometry and synchrotron reflectivity measurements. Studies including surface grating created by photolithography methods (the surface grating were of the same material as the substrate) and stepped surface created by the intentionally off-oriented surface were performed. The X-ray triple crystal arrangement allows us to measure reciprocal space maps of the scattered intensity, separating the intensity contributions of the scattered truncation rods on the first kind of samples. The synchrotron non-specular reflectivity measurements at ESRF were essential for proving the existence of stepped surfaces and examination of their structure.
Keywords: GaAs, high-resolution X-ray diffraction, X-ray reflectivity, surface grating, reciprocal space map
  • Poster
    19th European Crystallographic Meeting (ECM19), August 25-31, 2000, Nancy (France)

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Publ.-Id: 3726


Strain and SiC crystallite formation in carbon implanted silicon

Eichhorn, F.; Schell, N.; Mücklich, A.; Matz, W.; Kögler, R.
SiC formation by implantation of C ions into silicon is not a single-step process [1]. The implantation results in an elastic distortion of the Si host lattice and in a formation of crystalline SiC particles or their prestages depending on ion fluence and thermal conditions.
One part of the samples was prepared by implantation of C ions with an energy of 195 keV into Si (001) wafers at fluences varying from 5E15 ions/cm2 to 4E17 ions/cm² and temperatures between room temperature and 800°C. The other part was produced by implantation of 3.25E17 /cm² of C (45 keV) ions at 500 °C and a subsequent annealing at 1200°C for 2 h. The whole fluence was applied as well in one step as in three steps, respectively. The maximum of the carbon content lies in a depth of 130 nm for ions with an energy of 45 keV and at 570 nm for ions with an energy of 195 keV, respectively.
The growth of the SiC particles and the strain in the Si matrix and its relaxation were studied with different x-ray scattering techniques: high-resolution diffraction, wide-angle diffraction for the phase identification [2], grazing incidence diffraction for particle size determination, reciprocal space mapping (RSM) and texture studies for revealing the orientation alignment of the particles to the matrix. Mostly the use of Synchrotron radiation was necessary in order to have a clearly detectable signal in spite of the very small volume part of SiC. Furthermore, high resolution diffraction for strain studies requires radiation with a low divergence. The material research goniometer of the Rossendorf Beamline (ROBL) at the ESRF Grenoble [3] enables such studies which allow to follow the early stage of phase formation.
From the measurements it can be stated:
1. At the lowest ion fluence a significant Si lattice expansion on the order of 1E-3 is observed. However, no crystalline SiC precipitates were found.
2. Intermediate ion fluences and temperatures generate very small SiC particles (pre-stages) with enhanced lattice spacings in relation to the value of 3C-SiC. Due to the SiC particle formation the strain in the Si lattice is reduced.
3. Finally, for the highest fluences and temperatures crystalline 3C-SiC particles are found. The SiC lattice itself is only negligible strained if the phase formation occurs during a high-temperature implantation process.
4. As it was revealed by RSM and texture studies the SiC crystallites are aligned to the Si host lattice in such a way that the cubic crystallographic axes of matrix and particles coincide within an accuracy of 2.5° to 5°. A narrower distribution of the SiC crystallite orientation is formed by implantation at higher temperatures. Elevated temperature during implantation is supposed to be more effective in forming an aligned crystallite distribution than a subsequent annealing even at higher temperature.
[1] M. Deguchi et al., Jap. J. Appl. Phys. 31, 343 (1992)
[2] F. Eichhorn et al., J. Appl. Phys. 86, 4184 (1999)
[3] W. Matz et al., J. Synchrotron Rad. 6, 1076 (1999)

Keywords: SiC, Si, ion beam synthesis, X-ray diffraction, lattice strain, texture study, synchrotron X-rays
  • Lecture (Conference)
    5th Biennial Conference on High Resolution X-ray Diffraction and Topography XTOP-2000;, September 13 - 15, 2000, Ustron-Jaszowiec (Poland)

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Publ.-Id: 3725


Structural relation between Si and SiC formed by carbon ion implantation

Eichhorn, F.; Kögler, R.; Mücklich, A.; Schell, N.; Matz, W.
SiC ion beam synthesis by implantation of C ions into Si is a multiple-step process. In our experiments C ion implantation was performed at TII = RT ... 800 °C to a C concentration in the range of 0.3 to 33.5 at% into Si and SIMOX substrates. SiC phase formation and the related lattice strain were studied by different synchrotron X-ray scattering techniques using ROBL at ESRF Grenoble and by transmission electron microscopy:
1. Low ion fluences result in a Si lattice expansion in the order of 1E-3.
2. Intermediate ion fluences and temperatures generate small SiC pre-cursors with enhanced lattice spacings and reduced strain in the Si lattice.
3. High fluences and temperatures form 3C-SiC crystallites with three types of orientation:
- random-like orientation
- fibre texture with axis parallel to the surface normal with a mean orientation spread of 6°
- high alignment to the Si matrix: SiC<001> || Si<001> and SiC<110> || Si<110> due to a partial coherent growth of SiC in the Si matrix. The orientation spread is in the range from 2° to 5°.
Ion beam synthesis of SiC in Si at elevated temperatures favours the growth of highly oriented crystallites.

Keywords: SiC, Si, ion beam synthesis, X-ray diffraction, texture study, synchrotron X-rays
  • Poster
    E-MRS2001 Spring Meeting, June 5 - 8, 2001, Strasbourg (France)

Permalink: https://www.hzdr.de/publications/Publ-3724
Publ.-Id: 3724


Der Freie-Elektronen-Laser in Dresden/Rossendorf und seine Anwendungen in der Infrarot-Spektroskopie von Halbleitern und anderen Systemen

Helm, M.
Am Forschungszentrum Rossendorf wird zur Zeit ein Freie-Elektronen-Laser (FEL) gebaut, der Ende 2001 betriebsfertig sein soll. Mittelfristig soll ein Wellenlängenbereich von 5-200 um überstrichen werden können. Ich möchte einen Überblick über dieses Projekt geben, mit Darstellung der angeschlossenen experimentellen Infrastruktur. Desweiteren möchte ich über die möglichen spektroskopischen Anwendungen sprechen, die im Prinzip alle Systeme mit niederenergetischen Anregungen (10-100 meV) betreffen. Der Schwerpunkt dabei wird, gemäß meines Erfahrungshintergrundes, auf dem Gebiet der Halbleiter-Quantenstrukturen liegen.
Keywords: semiconductors, free-eelctron-laser, infrared spectroscopy
  • Lecture (others)
    Seminarvortrag Universität Giessen (25.01.2001)

Permalink: https://www.hzdr.de/publications/Publ-3723
Publ.-Id: 3723


Elektronen in künstlichen Halbleiterstrukturen: vom Modellsystem für Quantenmechanik und Festkörperphysik zum Quantenbauelement

Helm, M.
please contact the author
Keywords: semiconductors quantum structures
  • Lecture (others)
    Kolloquium an der TU Dresden (23.01.2001)

Permalink: https://www.hzdr.de/publications/Publ-3722
Publ.-Id: 3722


Structure refinement of the silicon carbide polytypes 4H and 6H: unambiguous determination of the refinement parameters

Bauer, A.; Reischauer, P.; Kräusslich, J.; Schell, N.; Matz, W.; Götz, K.
The atomic positions of the silicon carbide polytypes 6H and 4H differ slightly from an ideal tetrahedron. These small deviations can be investigated by X-ray diffraction of so-called "quasiforbidden" reflectios, which are very sensitive to the extremly small variations in the structure.
Keywords: SiC; atomic structure; synchrotron X-ray diffraction
  • Acta Cryst. A57 (2001) 60-67

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Publ.-Id: 3721


Formation of the phases Ti3Al and TiAl by high dose implantation of Aluminium into Titanium

Tsyganov, I. A.; Wieser, E.; Matz, W.; Mücklich, A.; Reuther, H.
formation of buried intermetallic Ti-Al-phases by high doose Al implantation
Keywords: ion implantation; titanium; X-ray diffraction, TEM, AES
  • Contribution to proceedings
    1st International Congress on Radiation Physics and Chemistry of Condensed Matter, High Current Electronics, and Modifikation of Materials with Particle Beams and Plasma Flows, Tomsk, Russia, Sept. 14 - 29, 2000

Permalink: https://www.hzdr.de/publications/Publ-3720
Publ.-Id: 3720


Modification of Titanium by ion implantation of Calcium and/or Phosphorus

Tsyganov, I. A.; Wieser, E.; Matz, W.; Reuther, H.; Oswald, S.; Pham, M. T.; Richter, E.
study of implantation treatment of Ti with Ca and P for improving hydroxylapatite formation
Keywords: ion implantation, hydroxylapatite, X-ray diffraction; AES
  • Contribution to proceedings
    1st International Congress on Radiation Physics and Chemistry of Condensed Matter, High Current Electronics, and Modifikation of Materials with Particle Beams and Plasma Flows, Tomsk, Russia, Sept. 14 - 29, 2000

Permalink: https://www.hzdr.de/publications/Publ-3719
Publ.-Id: 3719


Rossendorfer Beamline ROBL in Grenoble: Synchrotronstrahlung für Ökologie- und Materialforschung

Matz, W.
Übersicht über ROBL / ausgewählte Ergebnisse
  • Lecture (others)
    Tag der offenen Tür des FZR, 16. September 2000

Permalink: https://www.hzdr.de/publications/Publ-3718
Publ.-Id: 3718


Influence of thermal treatment and cyclic plastic deformation on the defect structure in ultrafine-grained nickel

Thiele, E.; Bretschneider, J.; Hollang, L.; Schell, N.; Holste, C.
Ultrafine-grained nickel samples were submitted to thermal treatment and cyclic plastic deformation in order to investigate the stability of the defect structure. Investigations by means of synchrotron radiation diffraction revealed that the mean volume expansion, long-range and short-range internal strains are diminished in consequence of the cyclic plastic deformation.
Keywords: ultrafine-grained nickel, cyclic plastic deformation, synchrotron X-ray diffraction, internal strains
  • Contribution to proceedings
    In: T. C. Lowe and R. Z. Valiev (eds.) Investigations and Applications of Severe Plastic Deformation, Proceedings of NATO Advanced Research Workshop, Moscow, Aug. 2 - 6 1999; Kluwer Academic Publishers, (2000) 173-178

Permalink: https://www.hzdr.de/publications/Publ-3717
Publ.-Id: 3717


Change of internal strains in ultrafine-grained nickel due to cyclic plastic deformation

Thiele, E.; Hecker, M.; Schell, N.
Ultra-fine grained nickel samples were cyclically deformed at room temperature and at 200°C. The mean grain size of about 200 nm, determined by SEM and from the broadening of synchrotron diffraction profiles remained nearly constant, whereas the spectrunm of internal strains changed in consequence of the cyclic deformation. The relation between the profile shape ans asymmetry and the {hkl} reflection type suggests the existence of long range granular stresses in the original ufg samples.
Keywords: ultrafine-grained nickel, cyclic plastic deformation, synchrotron X-ray diffraction, diffraction profile analysis, internals strains and stresses
  • Materials Science Forum 321-324 (2000) 598-603

Permalink: https://www.hzdr.de/publications/Publ-3716
Publ.-Id: 3716


Characterisation of crystallinity of SiC-surface layers produced by ion implantation

Theodossiu, E.; Baumann, H.; Klimenkov, M.; Matz, W.; Bethge, K.
Carbon implantations into silicon were carried out in order to form thin surface layers of SiC. Single crystalline <100> silicon samples were implanted with 40 keV 13C ions with a fluence of 3.8x1017 ions/cm2 and subsequently thermally treated under high vacuum conditions at different temperatures using a 20 keV electron beam. The isotope 13C offers the advantage to measure the carbon redistribution caused by the thermal treatment process with the nuclear resonance reaction analysis. The crystallinity of the SiC surface layers is studied by X-ray diffraction and transmission electron microscopy measurements. A polycrystalline 3C-SiC surface layer with a low content of 6H-SiC grains is formed with a thickness of about 70 nm. The analysis of high resolution TEM micrographs from the interface region shows obviously that the 6H-SiC phase coexists with the 3C-SiC modification in SiC layer.



Keywords: ion implantation, silicon carbide, 6H-SiC, NRRA, XRD, TEM
  • Phys. Stat. Sol. (a) 182 (2000) 653-660

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Publ.-Id: 3715


X-ray structure characterization of barriers for Cu metallization

Mattern, N.; Hecker, M.; Fischer, D.; Wenzel, C.; Schell, N.; Matz, W.; Engelmann, H.; Zschech, E.
The possibilities and limitations of X-ray scattering techniques are discussed for the structure analysis of Ta-N barriers for Cu metallization.
Keywords: X-ray diffraction; Ta barriers; synchrotron radiation
  • Microelectronics Reliability 40(2000) 1765-1770

Permalink: https://www.hzdr.de/publications/Publ-3714
Publ.-Id: 3714


Dissociative water vapour absorption in BaZr0.85Y0.15O2.925/H2O: pressure-compositions isotherms in terms of Fermi-Dirac statistics

Groß, B.; Engeldinger, J.; Grambole, D.; Herrmann, F.; Hempelmann, R.
Thin films of proton-conducting BaZr0.85Y0.15O2.925 perovskite-type ceramics, prepared in a sol-gel process by multiple dip-coating on silicon single crystal wafers, and powder samples, prepared by the conventional carbonate route, were charged with hydrogen by dissociative water absorption at definite values of water vapour pressures and temperatures. The absolute content of the absorbed hydrogen was determined ex situ at room temperature using the 15N nuclear resonance reaction analysis. From the resulting water vapour pressure-hydrogen composition isotherms the absorption enthalpies and entropy were caculated, using our two site model, based on Fermi-Dirac statistics.
  • Phys. Chem. Chem. Phys., 2000, 2, 297-301

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Publ.-Id: 3713


Application of the Tikhonov Regularization Method to the EXAFS analysis of UO2(H2AsO4)2 x H2O

Zayarnaya, T.; Reich, T.; Hennig, C.; Funke, H.
We consider the possibility to determine structural parameters from partial pair correlation functions (PCF's) for UO2(H2AsO4)2 x H2O assuming that its crystal structure is unknown. Since UO2(HAsO4) x 4H2O is chemically similar to UO2(H2AsO4)2 x H2O, we wanted to investigate whether the scattering characteristics calculated by FEFF-8 for the uranium hydrogen arsenate with a known crystal structure are transferable for the analysis of the uranium dihydrogen arsenate.
The Tikhonov regularization method was applied to solve the inverse ill-posed problem of finding up to three partial PCF's from one EXAFS spectrum of UO2(H2AsO4)2 x H2O. From the U L3-edge EXAFS spectrum, we determined the U-U, U-As, and U-O PCF's. The As-As, As-U, and As-O PCF's were received from the As K-edge EXAFS spectrum. The interatomic distances obtained for the first and in several cases also for the second coordination shell of all pairs are in agreement with recently published crystallographic values. This demonstrates that the Tikhonov regularization method is a powerful tool for the structural analysis of samples for which only chemical information (oxidation state, elemental composition, type of ligands) is known.

* Corresponding author: zayarnaya@imp.uran.ru
  • Lecture (Conference)
    Actinide-XAS-2000 Workshop Proceedings, Grenoble, Sept. 10.-12.2000

Permalink: https://www.hzdr.de/publications/Publ-3711
Publ.-Id: 3711


EXAFS Study of U(VI) Compounds: A New Approach to Data Analysis

Babanov, Y. A.; Zayarnaya, T.; Reich, T.; Funke, H.

The regularization method is applied to determine three partial pair correlation functions (PCF) from one EXAFS spectrum. The mathematical procedure is discussed and applied to the EXAFS analysis of UO-2(HAsO4) x 4H2O.
The measurements were performed at the Rossendorf Beamline (ROBL) at the ESRF in Grenoble. The As K-edge and the U L3-edge absorption spectra were recorded in transmission mode at temperatures of 41 K and 15 K, respectively. From the U L3-edge EXAFS spectrum, we obtain the PCF's of the pairs U-U, U-As, and U-O and determine the structural parameters for the first and the second coordination shells of each pair. The PCF's of the pairs As-U, As-As, and As-O are obtained from the As K-edge EXAFS spectrum.










  • Lecture (Conference)
    Actinide-XAS-2000 Workshop Proceedings, Grenoble Sept. 10-12., 2000

Permalink: https://www.hzdr.de/publications/Publ-3710
Publ.-Id: 3710


Tetraaquatrinitratoeuropium(III) dihydrate

Stumpf, T.; Bolte, M.
In the title compound, [Eu(NO3)3(H2O)4]·2H2O, the Eu atom is ten co-ordinated by three bidentate nitrates and four water molecules. Furthermore, two water molecules are included in the crystal structure forming a complicated network of hydrogen bonds. [Eu(NO3)3(H2O)4]·2H2O is isostructural with other lanthanide analogues.

Acta Cryst. (2001) E (submitted)
  • Acta Cryst. E

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Publ.-Id: 3709


Development of bubble size distributions in vertical pipe flow by consideration of radial gas fraction profiles

Lucas, D.; Krepper, E.; Prasser, H.-M.
A new method for the prediction of the development of the bubble size distribution along the flow path is presented. It combines models for bubble coalescence and break-up with the calculation of radial gas fraction profiles. This model bases on the assumption of the equilibrium of the forces acting on a bubble perpendicularly to the flow direction. A large number of bubble classes is considered and the radial profile of the liquid velocity is taken into account.

The results of the model are compared with experimental data for a number of gas and liquid volume flow rates. The experiments were performed at a vertical test loop in Forschungszentrum Rossendorf (inner diameter 51.2 mm) using a wire mesh sensor. The sensor enables the determination of void distributions in the cross section of the loop. A special evaluation procedure supplies as well bubble size distributions as local distributions of bubbles within a predefined interval of bubble sizes.
  • Lecture (Conference)
    4th International Conference on Multiphase Flow, New Orleans, May 27 - June 1, 2001, Conference-CD, Paper 378
  • Contribution to proceedings
    4th International Conference on Multiphase Flow, New Orleans, May 27 - June 1, 2001, Conference-CD, Paper 378

Permalink: https://www.hzdr.de/publications/Publ-3708
Publ.-Id: 3708


Acid Rock Drainage samples from an abandoned Zn-Pb-Ag mine investigated by XAS

Moll, H.; Zaenker, H.; Richter, W.; Brendler, V.; Reich, T.; Hennig, C.; Rossberg, A.; Funke, H.; Kluge, A.
In the aqueous environment of abandoned ore mines, iron sulphide ore crystals play a key role in the sulphide oxidation and water mineralization process occurring there. Highly miner-alised, red-coloured solutions are formed by weathering of ore particles which causes acid rock drainage (ARD). Major cationic components (>1 g/l) of the ARD solution under study were Zn, Fe, Mg, Al, and Mn. Important minor components were toxic heavy metals, e.g. As, Cu, Pb, and Cd. This XAS investigation deals with the in-situ characterisation of the near-order surrounding of As in ARD solutions containing colloidal particles as well as with the determination of the particle mineralogy. The atomic surrounding of Fe and As in ARD samples is compared to those found in model compounds. The presented study is an example for the broad applicability of X-ray absorption spectroscopy (XAS) techniques to environmental research.
Keywords: XAS, EXAFS, particles, Fe, As, ARD
  • Poster
    11th ESRF Users' Meeting, Grenoble, 16-21 February 2001 Workshop, Satellite to the ESRF Users' Meeting Environmental Studies Using Neutron and Synchrotron Facilities

Permalink: https://www.hzdr.de/publications/Publ-3707
Publ.-Id: 3707


Ion Beam Synthesis of SiC-Diamond-Heterostructures

Heera, V.
Both, silicon carbide (SiC) and diamond are wide band gap semiconductors with excellent electronic properties. Unfortunately, there has been only limited success in producing n-type regions in diamond or p-type regions in SiC. On the other hand, n-type doping of SiC by nitrogen (N) implantation and p-type doping of diamond by boron (B) implantation are well-established processes. Therefore, it is an obvious idea to combine the materials in order to exploit this complementary behavior for the fabrication of p-n-heterojunctions or n-type regions in insulating diamond. Preliminary experiments have shown that ion beam synthesis could be a suitable process for the production of SiC-diamond-heterostructures in microscopic regions. There are two ways to achieve these heterostructures: (i) diamond formation by high dose carbon (C) implantation in crystalline SiC and (ii) SiC formation by high dose silicon (Si) implantation in natural diamond. The implantation must be carried out at elevated temperatures (> 700°C) in order to avoid accumulation of implantation damage. Epitaxial, nm-sized diamond or SiC precipitates with spherical or platelike shape, respectively, are formed inside the host crystals by the ion beam synthesis.
Keywords: SiC, diamond, ion implantation, phase formation, ion beam synthesis
  • Compound Semiconductor 7 (2001) No. 3, 43

Permalink: https://www.hzdr.de/publications/Publ-3706
Publ.-Id: 3706


Three VVER-1000 Tests Suitable for the Validation of Coupled Neutronic / Thermal-hydraulic Codes

Danilin, S.; Ilieva, B.; Khalimonchuk, V.; Mittag, S.; Weiß, F.-P.
In the first test, carried out in the NPP Balakovo-4 (Russia), one of the two working feed water pumps was turned off at nominal power. The control system automatically reduced the reactor power down to 45 % of the nominal level. The coolant heat-up decreased proportionally to the power reduction. In the secondary circuit, the pumping power of the second feed water pump was increased in order to compensate some part of the missing feed water flow. In the following, the power of the second pump was reduced again to match the decreasing thermal power of the primary circuit. Corresponding changes in the steam generator water levels were observed. - The initiating event for a transient observed in the Zaporoshye-6 VVER-1000 (Ukraine) was the degradation of the turbo-generator power from 1000 MW down to the house load level of 50 MW. The reaction of the core control system and the behaviour of the primary circuit were similar to that in the Balakovo case. Immediately after the drastic reduction of the load level, the turbine started increasing its rotation speed. In order to prevent turbine damage, the steam control valves immediately reduced the steam flow to the turbine. Thus the turbine speed was stabilized, but the main steam header pressure started increasing. The turbine bypass valves were opened reducing the pressure quickly to its previous level. - The third test was carried out in the NPP Kozloduy-6 (Bulgaria). At 90 % of nominal power, two neighbouring main coolant pumps were switched off. The power was reduced to 35 %. Immediately after the transient initiation, the pressure in the primary circuit began to drop. All four pressurizer heaters started working to stabilize pressure. - The data measured in the three tests are useful for the validation of coupled codes.
  • Lecture (Conference)
    NEA/NSC Workshop on the Preservation of Experimental Integral Reactor Physics Data, 18-19 May 2000, Budapest, Hungary

Permalink: https://www.hzdr.de/publications/Publ-3705
Publ.-Id: 3705


Validation of coupled neutron-kinetic/thermal-hydraulic codes for VVERs

Mittag, S.; Kliem, S.; Weiß, F.-P.; Kyrki-Rajamäki, R.; Hämäläinen, A.; Langenbuch, S.; Danilin, S.; Hadek, J.; Hegyi, G.; Kuchin, A.; Panayotov, D.
Three-dimensional hexagonal reactor dynamic codes have been developed for VVER type reactors and coupled with different thermal hydraulic system codes. Under the auspices of the EU's Phare programme, these codes have been validated against real plant transients by the participants from several countries. Data measured during tests in the Balakovo-4 VVER-1000 and the Loviisa-1 VVER-440 have been analysed by the codes. Critical boron concentrations, 3-D core power distributions, time behaviour of total fission power, coolant temperatures and pressures were the main parameters utilised in the validation. Good accuracy of the results was generally achieved, comparable to the measurement accuracy. The confidence in the results of the different code systems has increased and the consequences of certain model changes could be evaluated.
  • Lecture (Conference)
    Proc. of Tenth Symposium of AER on VVER Reactor Physics and Reactor Safety, Moscow, Russia, September 18-22, 2000, 763-781
  • Contribution to proceedings
    Proc. of Tenth Symposium of AER on VVER Reactor Physics and Reactor Safety, Moscow, Russia, September 18-22, 2000, 763-781

Permalink: https://www.hzdr.de/publications/Publ-3704
Publ.-Id: 3704


19F(p,p'gamma)19F and 18O(p, gamma)19F gamma-ray interferences studied on liquids

Grambole, D.; Neelmeijer, C.; Noll, K.; Herrmann, F.
The interference effects for the 110 keV and 197 keV gamma-ray lines of the nuclear reactions 19F(p, p'gamma)19F and 18O(p, gamma)19F were studied quantitatively. For this, thick liquid targets were examined by PIGE using an external proton beam of 3.4 MeV energy. Several grades of dilutions were prepared from 76.3% 18O enriched H2O and from 1000 ppm F standard NaF solution. From this, a data base was obtained in order to extrapolate the 110 keV and 197 keV gamma-ray yields of the 18O(p, gamma)19F reaction for a target of water containing 0.2 % 18O. As a result it was obtained that, for fluorine in oxygen-rich materials, the reaction 19F(p, p'gamma)19F allows minimum detection limits of (1.06 ± 0.12) at.ppm and (1.85 ± 0.2) at.ppm for the 110 keV and 197 keV gamma-rays, respectively.
Keywords: PIGE; Fluorine; Oxygen-18; External beam; Liquid target
  • Nuclear Instruments and Methods in Physics Research B 161-163 (2000) 269-274

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Permalink: https://www.hzdr.de/publications/Publ-3703
Publ.-Id: 3703


Verfahren zur Dotierung von Siliziumkarbid-Halbleiterbereichen

Heera, V.
Der Erfindung liegt die Aufgabe zu Grunde, mit geringerem Aufwand in der Tiefe homogen dotierte SiC-Halbleiterbereiche mit einem schmalen Übergangsbereich zum Substrat zu erzeugen.
  • Patent
    Patentanmeldung 100 62 212.7
  • Patent
    DE 100 62 212 C1

Permalink: https://www.hzdr.de/publications/Publ-3701
Publ.-Id: 3701


Verfahren zur Herstellung von integrierten Abtastnadeln

Schmidt, B.; Bischoff, L.; Eng, L.
Aufgabe der Erfindung ist es, ein Verfahren zu schaffen, das die Erzeugung von miniaturisierten, integrierten Abtastnadeln, bestehend aus Support, Biegebalken und hohler Nadelspitze mit und ohne Apertur, erlaubt und die somit bevorzugt für den Einsatz in der SNOM geeignet sind.
  • Patent
    DE 100 57 656 C1
  • Patent
    EP 1 209 689 A2
  • Patent
    EP 1 209 689 B1

Permalink: https://www.hzdr.de/publications/Publ-3700
Publ.-Id: 3700


Steuereinrichtung für einen Kühlkreislauf

Willschütz, H.-G.
Der Erfindung liegt die Aufgabe zugrunde, eine Steuereinrichtung für einen Kühlkreislauf vorzuschlagen, die sicher und einfach auch bei einem schweren Störfall eine Kühlung des Reaktordruckbehälters sicherstellt. Dabei soll auf den Einsatz von Fremd-energie verzichtet werden.
  • Patent
    DE 100 41 779 C1
  • Patent
    WO 02/17331 A1

Permalink: https://www.hzdr.de/publications/Publ-3699
Publ.-Id: 3699


Abstützvorrichtung für Stahlbehälter

Willschütz, H.-G.
Der Erfindung liegt die Aufgabe zugrunde, eine Abstützvorrichtung vorzuschlagen, mit der eine vertikale Unterstützung des Stahlbehälters im Falle von außergewöhnlich hoher Temperatur und/oder Druck gewährleistet wird, ohne die Kühlung des Stahlbehälters zu beeinträchtigen.
  • Patent
    DE 100 41 778 A1
  • Patent
    WO 02/16821 A2
  • Patent
    De 100 41 778 C2

Permalink: https://www.hzdr.de/publications/Publ-3698
Publ.-Id: 3698


Einrichtung zur lokalen Bestimmung von Strömungsgeschwindigkeiten

Eckert, S.; Witke, W.; Gerbeth, G.
Der Erfindung liegt die Aufgabe zugrunde, eine Einrichtung zur Messung von Strömungsgeschwindigkeiten vorzuschlagen, die auch in nichttransparenten Fluiden einsetzbar ist und keinen Einschränkungen bei kleinen Geschwindigkeitswerten, turbulenten Geschwindigkeitsschwankungen, hohen Temperaturen und der Richtung der Strömung unterliegt.
  • Patent
    Patentanmeldung 100 37 331.3
  • Patent
    DE 100 37 331 C1

Permalink: https://www.hzdr.de/publications/Publ-3697
Publ.-Id: 3697


Schaltungsanordnung zur Erzeugung positiver und negativer pulsförmiger Magnetfelder

Krug, H.; Eckert, D.
Der Erfindung liegt die Aufgabe zugrunde, insbesondere große Anlagen für positive und negative pulsförmige Magnetfelder mit deutlich geringerem Aufwand herstellen zu können.
Die Erfindung geht aus von einer Schaltungsanordnung, die im Wesentlichen aus einer Kondensatorbatterie, einer Hochfeldspule, einer Schutzdrossel, einem Thyristorschalter, einer Crowbardiode, einem Crowbarwiderstand und mehreren Trennkontakten besteht.
  • Patent
    DE 100 30 566 A1
  • Patent
    DE 100 30 566 C2
  • Patent
    WO 01/98792 A1

Permalink: https://www.hzdr.de/publications/Publ-3696
Publ.-Id: 3696


Verfahren und Anordnung zur kontaktlosen Bestimmung von räumlichen Geschwindigkeitsverteilungen in elektrisch leitfähigen Flüssigkeiten

Stefani, F.; Gerbeth, G.; Gundrum, T.; Eckert, S.; Cramer, A.
Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren und eine Anordnung zur Bestimmung von räumlichen Geschwindigkeitsverteilungen in elektrisch leitfähigen Flüssigkeiten vorzuschlagen, die für alle Geschwindigkeitskomponenten reproduzierbare Ergebnisse garantieren und in denen jeglicher Kontakt mit der Flüssigkeit oder den sie einschließenden Wänden vermieden wird.
  • Patent
    Patentanmeldung 100 26 052.7
  • Patent
    DE 100 26 052 C2
  • Patent
    WO 01/90762 A1

Permalink: https://www.hzdr.de/publications/Publ-3695
Publ.-Id: 3695


Mechanisms of pit coarsening in ion erosion of fcc(111) surfaces: A kinetic 3D lattice Monte-Carlo study

Strobel, M.; Heinig, K.-H.; Michely, T.
An atomic simulation approach toion erosion of fcc(111) surfaces is presented. In a fully 3D kinetic lattice Monte-Carlo model thermodynamically activated processes like adatom, step-edge or surface vacancy diffusion are combined with ballistic eects due to single ion impacts, i.e. sputtering, adatom and surface vacancy generation. In the course of erosion nucleation of surface vacancy islands, their growth, both laterally and vertically, and subsequent coarsening of these pits is observed. For removal of up to theta = 6 monolayers the evolution of the surface is characterized in terms of the roughness and height-height-correlation function. The simulation results are discussed with respect to low-energy noble gas ion erosion experiments of Pt(111) surfaces [M. Kalff, et al., Surf. Sci., preceding paper]. By explicitly tuning specifc atomic transitions within the simulation it is demonstrated, that forbidden thermal adatom generation does hardly in uence the surface evolution. Suppressed step-edge diffusion, however, considerable slows down pit coarsening and impedes pit shape relaxation, emphasizing the importance of this smoothening process in ion erosion.
  • Surface Science 486 (1-2) Jul 2001 p.136-156

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Publ.-Id: 3694


Modeling and XPS Study of Precipitation and Oxidation of Ge in Ge+ implanted SiO2 layers

Borodin, V.; Heinig, K.-H.; Schmidt, B.; Oswald, S.
During annealing at 950°C in an oxidizing ambient, the redistribution of Ge in Ge+ implanted SiO2 layer is influenced by the germanium oxidation. Crystalline clusters precipitate immediately after sample heating. During the annealing an oxidation front proceeds into the layer, consuming crystalline clusters and leaving behind glassy precipitates barely visible by XTEM.
Sputtering depth profiling in conjunction with the x-ray photoelectron spectroscopy analysis was applied in order to identify the chemical state of both the precipitated Ge and that dissolved in the silicon dioxide matrix. For a reliable interpretation of the measured data, modeling of the physical processes involved in the depth profiling XPS technique was performed. It is shown that the depth profiling by ion beam sputtering causes collisional mixing of the subsurface region, which modifies the XPS signal. The results indicate possible improvement of the depth profiling XPS method to be used in future experiments.
  • Nuclear Instruments and Methods in Physics Research B, 178 May 2001 p. 115-119

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Publ.-Id: 3693


Ion irradiation of gold inclusions in SiO2: experimental evidence for inverse Ostwald ripening

Rizza, G.; Strobel, M.; Heinig, K.-H.; Bernas, H.
When sub mm size gold inclusions in SiO2 are irradiated with MeV gold ions, a ring of nanometer-size clusters is formed in their immediate vicinity. The size, density and radial distribution of these nanoclusters was determined. Our observations are in agreement with a recent prediction that in a driven system, under appropriate ion beam and temperature conditions, the steady-state solute concentration's dependence on precipitate size may be opposite to that expected from the equilibrium Gibbs-Thomson relation. Kinetic Monte-Carlo simulations account for additional experimental results: the irradiation-induced increase in solute concentration can promote nucleation of additional precipitates around the first ring. The latter finding contradicts the usual assumption that ion beam mixing hinders nucleation.
  • Nuclear Instruments and Methods in Physics Research B 178: 78-83 MAY 2001

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Permalink: https://www.hzdr.de/publications/Publ-3690
Publ.-Id: 3690


3D Kinetic Lattice Monte-Carlo Simulations of Ion Erosion of fcc(111) Surfaces

Strobel, M.; Heinig, K.-H.; Michely, T.
In high-dose ion implantation nanoclusters can be formed in a rather well-controlled manner as a function of implantation parameters like ion fluence, ion flux and substrate temperature. According to our current understanding of ion beam synthesis the evolution of nanoclusters is determined by the competition between ballistic and thermodynamic effects. While standard thermodynamics, i.e. the phase transition from a supersaturated solid-solution to second-phase precipitates via homogeneous nucleation and growth, gives a reasonable explanation for a variety of observed nanostructures, under irradiation conditions ballistic processes can modify the phase-ordering kinetics dramatically. By incorporating collisional mixing with the standard thermodynamical kinetic Monte-Carlo model, analytical predictions of irradiation effects of nanoclusters, e.g. inverse Ostwald ripening, are discussed.
Keywords: Ion erosion, fcc(111) surfaces, Kinetic lattice Monte-Carlo modeling
  • Nuclear Instruments and Methods in Physics Research B 178: 105-108 MAY 2001

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Permalink: https://www.hzdr.de/publications/Publ-3689
Publ.-Id: 3689


Shape evolution of oxidized silicon V-grooves during high dose ion implantation

Müller, T.; Heinig, K.-H.; Schmidt, B.; Mücklich, A.; Möller, W.
The evolution of the shape of oxidized V-grooves on (001) Si under high-dose Ge+ ion irradiation has been studied experimentally as well as theoretically. The shape of the V-grooves changes due to sputtering, re-deposition and swelling. An integro-differential equation has been derived which takes into account these 3 effects. The equation where solved numerically for the experimental conditions. Experimentally, V-grooves where formed by anisotropic etching and dry oxidation. XTEM images of as-oxidized
and as-implanted V-grooves where compared. The theoretically predicted SiO2 layer thickness reduction as well as the predicted surface shape change agree nicely with XTEM images. It is shown that sputtered material accumulates at the bottom of the V-grooves. At the same time implanted species accumulate in the bottom region of V-grooves, which can result in the formation of a very thin wire during subsequent annealing.
  • Nuclear Instruments and Methods in Physics Research B 178: 109-114 MAY 2001

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Permalink: https://www.hzdr.de/publications/Publ-3688
Publ.-Id: 3688


Shape evolution of oxidized silicon V-grooves during high dose ion implantation

Müller, T.; Heinig, K.-H.; Schmidt, B.; Mücklich, A.; Möller, W.
The evolution of the shape of oxidized V-grooves on (001) Si under high-dose
Ge+ ion irradiation has been studied experimentally as well as
theoretically. The shape of the V-grooves changes due to sputtering,
re-deposition and swelling. An integro-differential equation has been
derived which takes into account these 3 effects. The equation where solved
numerically for the experimental conditions. Experimentally, V-grooves where
formed by anisotropic etching and dry oxidation. XTEM images of as-oxidized
and as-implanted V-grooves where compared. The theoretically predicted SiO2
layer thickness reduction as well as the predicted surface shape change
agree nicely with XTEM images. It is shown that sputtered material
accumulates at the bottom of the V-grooves. At the same time implanted
species accumulate in the bottom region of V-grooves, which can result in
the formation of a very thin wire during subsequent annealing.
  • Lecture (Conference)
    E-MRS - IUMRS 2000 Spring Meeting, Symposium R: Materials Science with Ion Beams, Strasbourg, France, May 30 - June 2, 2000

Permalink: https://www.hzdr.de/publications/Publ-3687
Publ.-Id: 3687


3D Kinetic Lattice Monte-Carlo Simulations of Ion Erosion of fcc(111) Surfaces

Strobel, M.; Heinig, K.-H.; Michely, T.
In high-dose ion implantation nanoclusters can be formed in a rather well-controlled manner as a function of implantation parameters like ion fluence, ion flux and substrate temperature. According to our current understanding of ion beam synthesis the evolution of nanoclusters is determined by the competition between ballistic and thermodynamic effects. While standard thermodynamics, i.e. the phase transition from a supersaturated solid-solution to second-phase precipitates via homogeneous nucleation and growth, gives a reasonable explanation for a variety of observed nanostructures, under irradiation conditions ballistic processes can modify the phase-ordering kinetics dramatically.
By incorporating collisional mixing with the standard thermodynamical kinetic Monte-Carlo model, analytical predictions of irradiation effects of nanoclusters, e.g. inverse Ostwald ripening, are discussed.
  • Lecture (Conference)
    E-MRS - IUMRS 2000 Spring Meeting, Symposium R: Materials Science with Ion Beams, Strasbourg, France, May 30 - June 2, 2000

Permalink: https://www.hzdr.de/publications/Publ-3686
Publ.-Id: 3686


Ion irradiation of gold inclusions in SiO2: experimental evidence for inverse Ostwald ripening

Rizza, G.; Strobel, M.; Heinig, K.-H.; Bernas, H.
When sub mm size gold inclusions in SiO2 are irradiated with MeV gold ions, a ring of nanometer-size clusters is formed in their immediate vicinity. The size, density and radial distribution of these nanoclusters was determined. Our observations are in agreement with a recent prediction that in a driven system, under appropriate ion beam and temperature conditions, the steady-state solute concentration's dependence on precipitate size may be opposite to that expected from the equilibrium Gibbs-Thomson relation. Kinetic Monte-Carlo simulations account for additional experimental results: the irradiation-induced increase in solute concentration can promote nucleation of additional precipitates around the first ring. The latter finding contradicts the usual assumption that ion beam mixing hinders nucleation..
  • Lecture (Conference)
    E-MRS - IUMRS 2000 Spring Meeting, Symposium R: Materials Science with Ion Beams, Strasbourg, France, May 30 - June 2, 2000

Permalink: https://www.hzdr.de/publications/Publ-3685
Publ.-Id: 3685


Inverse Ostwald ripening under ion irradiation

Heinig, K.-H.; Strobel, M.
The steady-state behavior of plain interfaces and nanoclusters (NCs) under
ion irradiation has been studied analytically as well as by kinetic
Monte-Carlo (MC) simulations. In the two-phase system mixing of A-type atoms
into phase B region leads to a strong increase of the solute concentration
at low irradiation temperatures. For NCs the ion irradiation induced
elevated solute concentration depends on their sizes. The analytical form of
this size dependence is identical to that of NCs in equilibrium, i.e. it is
given by the Gibbs-Thomson relation. However, in contrast to equilibrium,
small NCs have a lower increase in solute concentration than larger ones.
This may result in a dramatically change of the evolution of NC ensembles:
The driven system can get a negative capillarity length for its interfaces
with the consequence of mass transport from large NCs to smaller ones, i.e.
inverse Ostwald ripening is observed. Thus, it is predicted theoretically
that a broad size distribution can be made narrow by ion irradiation. At
conditions not being too far from equilibrium this behavior has been proven
by a computer experiment. The MC simulations predict in addition to the
analytical result that at very high fluxes or low temperatures large NCs can
disintegrate due to the formation of smaller ones by nucleation.

Keywords: Ion irradiation, nanoclusters, non-equilibrium, Ostwald ripening, theory
  • Lecture (Conference)
    E-MRS - IUMRS 2000 Spring Meeting, Symposium R: Materials Science with Ion Beams, Strasbourg, France, May 30 - June 2, 2000

Permalink: https://www.hzdr.de/publications/Publ-3684
Publ.-Id: 3684


Atomistic Study of the Evolution of Nanoclusters in Ion Beam Synthesis

Strobel, M.; Heinig, K.-H.; Möller, W.
Ion implantation is an established tool to synthesize or to modify buried low-dimensional nanostructures (e.g. nanoclusters), which have become the basis of numerous technological applications. According to our current understanding of ion beam synthesis the evolution of nanostructures is determined by the competition between ballistic and thermodynamic effects. In this work it is shown, that a sound understanding of the diffusional interaction dynamics of nanoclusters can be achieved by kinetic 3D lattice Monte-Carlo simulations. In particular, the exploitation of the cluster size-concentration dependence (the Gibbs-Thomson relation) under pure thermal or ion irradiation conditions provides a wealth of physical information relevant for ion beam synthesis. Furthermore, evidence is presented, that within a certain parameter window of irradiation conditions collisional mixing induced nucleation of nanoclusters occurs.
Keywords: Ion beam synthesis, nanoclusters, nucleation, Ostwald ripening, collisional mixing, kinetic lattice Monte-Carlo modeling
  • Lecture (Conference)
    E-MRS - IUMRS 2000 Spring Meeting, Symposium R: Materials Science with Ion Beams, Strasbourg, France, May 30 - June 2, 2000

Permalink: https://www.hzdr.de/publications/Publ-3683
Publ.-Id: 3683


Modeling and XPS Study of Pricipitation and Oxidation of Ge in Ge+ implanted SiO2 layers

Borodin, V.; Heinig, K.-H.; Schmidt, B.; Oswald, S.
During annealing at 950oC in an oxidizing ambient, the redistribution of Ge in Ge+ implanted SiO2 layer is influenced by the germanium oxidation. Crystalline clusters precipitate immediately after sample heating. During the annealing an oxidation front proceeds into the layer, consuming crystalline clusters and leaving behind glassy precipitates barely visible by XTEM. Sputtering depth profiling in conjunction with the x-ray photoelectron spectroscopy analysis was applied in order to identify the chemical state of both the precipitated Ge and that dissolved in the silicon dioxide matrix. For a reliable interpretation of the measured data, modeling of the physical processes involved in the depth profiling XPS technique was performed. It is shown that the depth profiling by ion beam sputtering causes collisional mixing of the subsurface region, which modifies the XPS signal. The results indicate possible improvement of the depth profiling XPS method to be used in future experiments.
Keywords: Germanium, oxidation, silicon dioxide, X-ray photoelectron spectroscopy, modeling
  • Lecture (Conference)
    E-MRS - IUMRS 2000 Spring Meeting, Symposium R: Materials Science with Ion Beams, Strasbourg, France, May 30 - June 2, 2000

Permalink: https://www.hzdr.de/publications/Publ-3682
Publ.-Id: 3682


Morphology Evolution during Ion Erosion of fcc(111) Surfaces: A 3D Kinetic Lattice Monte-Carlo Study

Strobel, M.; Heinig, K.-H.; Michely, T.
Ion Erosion ...
  • Lecture (Conference)
    12th Int. Conf. Ion Beam Modifications of Materials (IBMM2000), Canela, Brazil, September 3 - 8, 2000

Permalink: https://www.hzdr.de/publications/Publ-3681
Publ.-Id: 3681


Nanocluster Evolution under Ion Irradiation

Heinig, K.-H.; Strobel, M.; Rizza, G.
An ensemble of nanoclusters embedded in a substrate evolves during thermal annealing by coarsening or Ostwald ripening, and, if the concentration of cluster material is sufficiently high, coalescence.
In this contribution it will be shown that by ion irradiation the evolution of nanoclusters can be modified or even dramatically changed. (i) Ion irradiation increases due to collisional detachments of atoms from clusters the steady-state solubility. Thus, cluster evolution is accelerated or happens at lower temperatures. (ii) Collisional detachment of atoms from nanoclusters is more efficient for large clusters than for small ones. This dependence on cluster size is opposite to that predicted by the Gibbs-Thomson law for thermally activated detachment. The "inverse" behaviour results in "Inverse Ostwald Ripening", i.e. a broad size distribution becomes narrower during annealing under ion irradiation. (iii) Under intense ion irradiation large clusters can evaporate and new nanoclusters will nucleate. A steady-state mean size, which is dependent on ion flux and temperature, can be found.
The new results listed above were predicted by an analytical theory and have been proven by kinetic lattice Monte-Carlo simulations and preliminary experiments.

Keywords: Ion irradiation, nanoclusters, annealing, Ostwald ripening, theory, computer simulation
  • Invited lecture (Conferences)
    12th Int. Conf. Ion Beam Modifications of Materials (IBMM2000), Canela, Brazil, September 3 - 8, 2000 (invited)

Permalink: https://www.hzdr.de/publications/Publ-3680
Publ.-Id: 3680


Synthese und Bearbeitung von Nanostrukturen mit Ionenstrahlen

Heinig, K.-H.
Unter Ionenbestrahlung laufen in der Festkörperoberfläche Prozesse weitab vom thermodynamischen Gleichgewicht ab. Übliche Prozeßabläufe können umgekehrt werden (z.B. inverses Ostwaldreifen), und geordnete Strukturen können sich ausbilden (z.B. wave-ordered-structures). Im Vortrag werden hierzu experimentelle und theoretische Untersuchungen vorgestellt. Es wird u.a. gezeigt, wie Nanocluster in Ordnungszustände gebracht werden können, die für mikroelektronische und mikrooptsche Anwendungen hochinteressant sind.
Keywords: Ionenstrahlsynthese, Nanocluster, Computersimulation, Thermodynamik
  • Lecture (others)
    Friedrich-Schiller Universität Jena, Physikalisch-Astronomische Fakultät, Vortrag am 17. 11. 2000

Permalink: https://www.hzdr.de/publications/Publ-3679
Publ.-Id: 3679


Physico-chemical characterization of seaborgium as oxide hydroxide

Hübener, S.; Taut, S.; Vahle, A.; Dressler, R.; Eichler, B.; Gäggeler, H. W.; Jost, D.; Piguet, D.; Türler, A.; Schädel, M.; Jäger, E.; Brüchle, W.; Schimpf, E.; Kirbach, U.; Trautmann, N.; Yakushev, A.
Seaborgium (element 106) was studied in comparison with tungsten in the O2-H2O(g)/SiO2(s)-system using high-temperature on-line isothermal gas chromatography. The 21-s nuclide 266Sg was produced in the 248Cm + 22Ne reaction at a beam energy of 119 MeV. The reaction products were continuously transported by a He(MoO3)-jet to the chromatography apparatus HITGAS. Group 6 element oxide hy-droxide molecules volatile at temperatures above 1000 K were formed at 1325 K by adding humid oxygen as reactive gas. 266Sg was unambiguously detected after gas chromatographic separation by measuring 266Sg-262Rf mother-daughter a-sf correlations. The experimental results demonstrate the volatility of seaborgium in humid oxygen, presumably as seaborgium oxide hydroxide as typical for both uranium (VI) and the group 6 elements.
Keywords: Seaborgium, group 6 elements, oxide hydroxide, reaction gas chromatography
  • Radiochimica Acta 89 (2001) 737-741

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Permalink: https://www.hzdr.de/publications/Publ-3678
Publ.-Id: 3678


Elastic constants of diamond-like amorphous carbon films: the effect of internal stresses

Belov, A.; Jäger, H.-U.
The extreme wear resistance and chemical inertness of tetrahedral, or
diamond-like, amorphous carbon (ta-C) make it a promising material for
wear-resistive mechanical coatings. The unique mechanical behaviour of ta-C
is related to the atomic structure of amorphous carbon and atomic scale
modeling becomes a valuable tool to study both growth mechanisms of ta-C
films and their mechanical properties. Here we report results of atomistic
calculations of elastic constants in ta-C films grown by a realistic
computer simulation of ion-beam deposition. The dependence of the elastic
constants on the ion energy is presented. Similar to the real as-grown
nonequilibrium (not annealed) ta-C films, the simulated structures possess
the high internal compressive stress, which can considerably effect on
elastic constants. An approach employed allows for the stress dependence of
elastic constants to be analysed. We demonstrate the variation of elastic
constants as a function of the internal stress, and therefore the
importance of nonlinear elastic properties in amorphous carbon.
Keywords: tetrahedral amorphous carbon, elastic constants, internal stresses
  • Lecture (Conference)
    E-MRS 2001 SPRING MEETING, June 5-8, 2001, Strasbourg (France), Symposium C: Protective Coatings and Thin Films

Permalink: https://www.hzdr.de/publications/Publ-3677
Publ.-Id: 3677


Structures of technetium and rhenium complexes

Leibnitz, P.; Reck, G.; Pietzsch, H.-J.; Spies, H.
Investigations in the 99mTc chemistry are stimulated by the search for new radiopharmaceuticals for nuclear medical applications. To understand the coordination mode of Tc with various complexing agents, macroscopic studies of technetium coordination chemistry are often performed using the low energy ß-emitting radionuclide 99Tc, which has a much longer half life (t1/2 = 2.12 x 105 years) than 99mTc, in the mg level.
Investigations of Re coordination chemistry are done in conjunction with Tc studies because Re possesses chemical properties similar to those of Tc. For some chemical tasks, Re provides a non-radioactive alternative to work with Tc radioisotopes. In addition, 186Re and 188Re are of great interest to nuclear medicine as they possess nuclear properties favorable for use in therapeutic radiopharmaceuticals.
Our investigations of Tc and Re coordination chemistry are toward this goal. A large series of technetium and rhenium complexes resulted from this studies have been characterized by X-ray crystal structure determinations.
This survey covers the structural investigations performed by P.Leibnitz and G.Reck (BAM) from 1992 till now. It summarizes results obtained in the Rossendorf technetium group and is not intended to compete with the well-written reviews published so far.

Keywords: technetium complexes, rhenium complexes, oxotechnetium(V) complexes, oxorhenium(V) complexes, Tc(III) mixed ligand complexes, Re(III) mixed ligand complexes, X-ray structural analysis
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-311 2001

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Permalink: https://www.hzdr.de/publications/Publ-3676
Publ.-Id: 3676


Calculation of intrinsic stresses in amorphous carbon films grown by molecular dynamics simulation: from the atomic to the macroscopic scale

Belov, A.; Jäger, H.-U.
We present a method of calculation and an estimate for the bulk intrinsic stress in nonequilibrium tetrahedral amorphous carbon (ta-C) films grown by a realistic atomic scale simulation of ion-beam deposition. The simulated films have a thickness of a few nanometers and reproduce the important features of the real as grown nonequilibrium (not annealed) structures such as the presence of a steady-state growth region with uniform properties, the large content of sp3 bonded atoms, and the high intrinsic compressive stress, which seriously limits the maximum thickness of films that can be deposited. Using slices from the nearly structurally uniform film region, a 3D periodic model was constructed for the bulk intrinsic stress calculation. Employing empirical interatomic potentials for carbon, atomic stresses as well as the bulk stresses were computed. The obtained value of the compressive stress for the transition from the graphitic-like carbon to ta-C is in a good agreement with experimental data for the stress threshold.
Keywords: tetrahedral amorphous carbon, thin films, intrinsic stress
  • Poster
    E-MRS 2001 SPRING MEETING, June 5-8, 2001, Strasbourg (France), Symposium A: Computational Materials Science Across Time and Length Scales

Permalink: https://www.hzdr.de/publications/Publ-3675
Publ.-Id: 3675


Erwärmung des Reaktordruckbehälters des Blocks 8 des KKW Greifswald bei der Zerlegung mittels Sägetechnik

Mössner, T.; Altstadt, E.; Böhmert, J.; Weiß, R.
Die Arbeit untersucht das Erwärmungsverhalten des Reaktordruckbehälters des Blockes 8 des KKW Greifswald bei der Zerlegung in Ringabschnitte mit einer Bandsäge. Mit dem Programm ANSYS wurde dazu ein thermisches Finite-Elemente-Modell erstellt. Dieses Modell ist an Hand vorhandener Temperaturmessdaten abgeglichen worden. Mit dem abgeglichenen Modell wurden abschließend die auftretenden Maximaltemperaturen für den Sägevorgang ermittelt. Diese liegen bei höchstens 200 °C.
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf, FZR-310 Januar 2001

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Permalink: https://www.hzdr.de/publications/Publ-3674
Publ.-Id: 3674


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