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4. Controlling Grain Boundary Segregation to Tune the Conductivity of Ceramic Proton Conductors.

Author

Kindelmann, Moritz, Povstugar, Ivan, Kuffer, Severin, Jennings, Dylan, Ebert, Julian N., Weber, Moritz L., Zahler, M. Pascal, Escolastico, Sonia, Almar, Laura, Serra, Jose M., Kaghazchi, Payam, Bram, Martin, Rheinheimer, Wolfgang, Mayer, Joachim, and Guillon, Olivier

Subjects
*ATOM-probe tomography, *SPACE charge, *CRYSTAL grain boundaries, *PROTON conductivity, *ATOMIC spectroscopy, *SOLID state proton conductors
Abstract

Acceptor‐doped barium zirconates are of major interest as proton‐conducting ceramics for electrochemical applications at intermediate operating temperatures. However, the proton transport through polycrystalline microstructures is hindered by the presence of a positive space charge potential at grain boundaries. During high‐temperature sintering, the positive charge acts as a driving force for acceptor dopant segregation to the grain boundary. Acceptor segregation to grain boundaries has been observed in sintered ceramics, but the fundamental relationship between the segregation kinetics and the protonic conductivity is poorly understood. Here, a comprehensive study of the influence of acceptor dopant segregation on the electrochemical properties of grain boundaries in barium zirconate ceramics is presented. An out‐of‐equilibrium model material that displays no detectable Y segregation at its grain boundaries is explicitly designed. This model material serves as a starting point to measure the kinetics of segregation and the induced changes in grain boundary conductivity upon varying thermal histories. Furthermore, the electrochemical results from impedance spectroscopy to atomic resolution transmission electron microscopy, atom probe tomography, and DFT simulations are correlated. It is discovered that acceptor dopant segregation drastically increases the proton conductivity in both the model system and several other application‐relevant compositions. [ABSTRACT FROM AUTHOR]

Published
2024
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5. The Effect of Y Addition on Oxidation Resistance of Bulk W-Cr Alloys.

Author

Reuban, Anicha, Chen, Jie, Povstugar, Ivan, Litnovsky, Andrey, Coenen, Jan Willem, Linsmeier, Christian, and Gonzalez-Julian, Jesus

Abstract

The self-passivating tungsten-based alloy W-11.4Cr-0.6Y (in wt.%) is a potential plasma-facing material for the first wall of future fusion reactors, which has been shown to suppress oxidation of tungsten and withstand temperatures of up to 1000 °C. In this study, the effect of Y addition on the microstructure and oxidation behavior of W-11.4Cr alloy at 1000 °C is analyzed by comparing it with W-11.4Cr-0.6Y, both prepared using identical synthesis routes. While the binary W-Cr alloy already exhibits improved oxidation resistance over pure W due to the formation of an outer Cr2WO6 layer, it still shows a tendency for spallation and, hence, is not protective. A continuous passivating chromia layer is only obtained with the addition of Y, and we demonstrate that it results in a 50-fold decrease in the oxide growth rate and eliminates the preferred growth of the oxide at edges seen in the binary alloy. Although a porous, complex oxide scale containing mixed oxide layers and WO3 is formed in both cases, the addition of Y results in lower porosity, which makes the oxide scale more adherent. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Smart Tungsten-based Alloys for a First Wall of DEMO

Author

Litnovsky, Andrey, Schmitz, Janina, Klein, Felix, De Lannoye, Karen, Weckauf, Sophie, Kreter, Arkadi, Rasinski, Marcin, Coenen, Jan W., Linsmeier, Christian, Gonzalez-Julian, Jesus, Bram, Martin, Povstugar, Ivan, Morgan, Thomas, Nguyen-Manh, Duc, Gilbert, Mark, Sobieraj, Damian, and Wróbel, Jan S.

Published
2020
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8. Growth and Electrical Characterization of Hybrid Core/Shell InAs/CdSe Nanowires

Author

Kaladzhian, Mane, primary, von den Driesch, Nils, additional, Demarina, Nataliya, additional, Povstugar, Ivan, additional, Zimmermann, Erik, additional, Jansen, Marvin Marco, additional, Bae, Jin Hee, additional, Krause, Christoph, additional, Bennemann, Benjamin, additional, Grützmacher, Detlev, additional, Schäpers, Thomas, additional, and Pawlis, Alexander, additional

Published
2024
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15. Advanced Self-Passivating Alloys for an Application under Extreme Conditions

Author

Litnovsky, Andrey, primary, Klein, Felix, additional, Tan, Xiaoyue, additional, Ertmer, Janina, additional, Coenen, Jan W., additional, Linsmeier, Christian, additional, Gonzalez-Julian, Jesus, additional, Bram, Martin, additional, Povstugar, Ivan, additional, Morgan, Thomas, additional, Gasparyan, Yury M., additional, Suchkov, Alexey, additional, Bachurina, Diana, additional, Nguyen-Manh, Duc, additional, Gilbert, Mark, additional, Sobieraj, Damian, additional, Wróbel, Jan S., additional, Tejado, Elena, additional, Matejicek, Jiri, additional, Zoz, Henning, additional, Benz, Hans Ulrich, additional, Bittner, Pawel, additional, and Reuban, Anicha, additional

Published
2021
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16. All‐Solid‐State Batteries: Nano‐Scale Complexions Facilitate Li Dendrite‐Free Operation in LATP Solid‐State Electrolyte (Adv. Energy Mater. 26/2021)

Author

Stegmaier, Sina, primary, Schierholz, Roland, additional, Povstugar, Ivan, additional, Barthel, Juri, additional, Rittmeyer, Simon P., additional, Yu, Shicheng, additional, Wengert, Simon, additional, Rostami, Samare, additional, Kungl, Hans, additional, Reuter, Karsten, additional, Eichel, Rüdiger‐A., additional, and Scheurer, Christoph, additional

Published
2021
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17. Nano‐Scale Complexions Facilitate Li Dendrite‐Free Operation in LATP Solid‐State Electrolyte

Author

Stegmaier, Sina, primary, Schierholz, Roland, additional, Povstugar, Ivan, additional, Barthel, Juri, additional, Rittmeyer, Simon P., additional, Yu, Shicheng, additional, Wengert, Simon, additional, Rostami, Samare, additional, Kungl, Hans, additional, Reuter, Karsten, additional, Eichel, Rüdiger‐A., additional, and Scheurer, Christoph, additional

Published
2021
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19. Advanced self-passivating alloys for an application under extreme conditions

Author

Litnovsky, Andrey, Klein, Felix, Tan, Xiaoyue, Ertmer, Janina, Coenen, Jan W., Linsmeier, Christian, Gonzalez-Julian, Jesus, Bram, Martin, Povstugar, Ivan, Morgan, Thomas, Gasparyan, Yury M., Suchkov, Alexey, Bachurina, Diana, Nguyen-Manh, Duc, Gilbert, Mark, Sobieraj, Damian, Wróbel, Jan S., Tejado, Elena, Matejicek, Jiri, Zoz, Henning, Benz, Hans Ulrich, Bittner, Pawel, Reuban, Anicha, Litnovsky, Andrey, Klein, Felix, Tan, Xiaoyue, Ertmer, Janina, Coenen, Jan W., Linsmeier, Christian, Gonzalez-Julian, Jesus, Bram, Martin, Povstugar, Ivan, Morgan, Thomas, Gasparyan, Yury M., Suchkov, Alexey, Bachurina, Diana, Nguyen-Manh, Duc, Gilbert, Mark, Sobieraj, Damian, Wróbel, Jan S., Tejado, Elena, Matejicek, Jiri, Zoz, Henning, Benz, Hans Ulrich, Bittner, Pawel, and Reuban, Anicha

Abstract

Self-passivating Metal Alloys with Reduced Thermo-oxidation (SMART) are under development for the primary application as plasma-facing materials for the first wall in a fusion DEMOnstration power plant (DEMO). SMART materials must combine suppressed oxidation in case of an accident and an acceptable plasma performance during the regular operation of the future power plant. Modern SMART materials contain chromium as a passivating element, yttrium as an active element and a tungsten base matrix. An overview of the research and development program on SMART materials is presented and all major areas of the structured R&D are explained. Attaining desired performance under accident and regular plasma conditions are vital elements of an R&D program addressing the viability of the entire concept. An impressive more than 104-fold suppression of oxidation, accompanied with more than 40-fold suppression of sublimation of tungsten oxide, was attained during an experimentally reproduced accident event with a duration of 10 days. The sputtering resistance under DEMO-relevant plasma conditions of SMART materials and pure tungsten was identical for conditions corresponding to nearly 20 days of continuous DEMO operation. Fundamental understanding of physics processes undergone in the SMART material is gained via fundamental studies comprising dedicated modeling and experiments. The important role of yttrium, stabilizing the SMART alloy microstructure and improving self-passivating behavior, is under investigation. Activities toward industrial up-scale have begun, comprising the first mechanical alloying with an industrial partner and the sintering of a bulk SMART alloy sample with dimensions of 100 mm × 100 mm × 7 mm using an industrial facility. These achievements open the way to further expansion of the SMART technology toward its application in fusion and potentially in other renewable energy sources such as concentrated solar power stations.

Published
2021

20. Smart tungsten-based alloys for a first wall of DEMO

Author

Litnovsky, Andrey, Schmitz, Janina, Klein, Felix, Lannoye, Karen De, Kreter, Arkadi, Rasinski, Marcin, Coenen, Jan Willem, Linsmeier, Christian, Gonzalez-Julian, Jesus, Bram, Martin, Povstugar, Ivan, Morgan, Thomas W, Nguyen-Manh, Duc, Gilbert, Mark R, Sobieraj, Damian, and Wrobel, Jan

Published
2019
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23. (Invited) Epitaxy of Direct Bandgap Group IV Si-Ge-Sn Alloys towards Heterostructure Light Emitters

Author

von den Driesch, Nils, primary, Stange, Daniela, additional, Rainko, Denis, additional, Povstugar, Ivan, additional, Breuer, Uwe, additional, Ikonic, Zoran, additional, Hartmann, Jean-Michel, additional, Schubert, Markus Andreas, additional, Capellini, Giovanni, additional, Sigg, Hans, additional, Mantl, Siegfried, additional, Grützmacher, Detlev, additional, and Buca, Dan, additional

Published
2018
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24. Advanced GeSn/SiGeSn Group IV Heterostructure Lasers

Author

von den Driesch, Nils, primary, Stange, Daniela, additional, Rainko, Denis, additional, Povstugar, Ivan, additional, Zaumseil, Peter, additional, Capellini, Giovanni, additional, Schröder, Thomas, additional, Denneulin, Thibaud, additional, Ikonic, Zoran, additional, Hartmann, Jean‐Michel, additional, Sigg, Hans, additional, Mantl, Siegfried, additional, Grützmacher, Detlev, additional, and Buca, Dan, additional

Published
2018
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25. Confinement of charge carriers in GeSn/SiGeSn heterostructures

Author

Rainko, Denis, von den Driesch, Nils, Ikonic, Zoran, Mantl, Siegfried, Grützmacher, Detlev, Buca, Dan Mihai, Stange, Daniela, Schulte-Braucks, Christian, Mussler, Gregor, Povstugar, Ivan, Breuer, Uwe, Zaumseil, Peter, Capellini, Giovanni, and Hartmann, Jean-Michel

Subjects
Condensed Matter::Materials Science, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect
Abstract

In this work, we discuss carrier confinement in double heterostructures and multiple quantum well GeSn/(Si)Ge(Sn) heterostructures, aiming for efficient light emitting devices. Several heterostructures are ep-itaxially grown and characterized in detail concerning their structural and optical properties. Theoretical band structure calculations are used to support exper-imental data and provide predictions for optimized heterostructures.

Published
2017

27. SiGeSn Ternaries for Efficient Group IV Heterostructure Light Emitters

Author

von den Driesch, Nils, primary, Stange, Daniela, additional, Wirths, Stephan, additional, Rainko, Denis, additional, Povstugar, Ivan, additional, Savenko, Aleksei, additional, Breuer, Uwe, additional, Geiger, Richard, additional, Sigg, Hans, additional, Ikonic, Zoran, additional, Hartmann, Jean-Michel, additional, Grützmacher, Detlev, additional, Mantl, Siegfried, additional, and Buca, Dan, additional

Published
2017
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28. Short-wave infrared LEDs from GeSn/SiGeSn multiple quantum wells

Author

Stange, Daniela, primary, von den Driesch, Nils, additional, Rainko, Denis, additional, Roesgaard, Søren, additional, Povstugar, Ivan, additional, Hartmann, Jean-Michel, additional, Stoica, T., additional, Ikonic, Zoran, additional, Mantl, Siegfried, additional, Grützmacher, Detlev, additional, and Buca, Dan, additional

Published
2017
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30. On Local Phase Equilibria and the Appearance of Nanoparticles in the Microstructure of Single‐Crystal Ni‐Base Superalloys

Author

Yardley, Victoria, primary, Povstugar, Ivan, additional, Choi, Pyuck‐Pa, additional, Raabe, Dirk, additional, Parsa, Alireza B., additional, Kostka, Aleksander, additional, Somsen, Christoph, additional, Dlouhy, Antonin, additional, Neuking, Klaus, additional, George, Easo P., additional, and Eggeler, Gunther, additional

Published
2016
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31. Advanced Scale Bridging Microstructure Analysis of Single Crystal Ni‐Base Superalloys

Author

Parsa, Alireza B., primary, Wollgramm, Philip, additional, Buck, Hinrich, additional, Somsen, Christoph, additional, Kostka, Aleksander, additional, Povstugar, Ivan, additional, Choi, Pyuck‐Pa, additional, Raabe, Dierk, additional, Dlouhy, Antonin, additional, Müller, Julian, additional, Spiecker, Erdmann, additional, Demtroder, Kathrin, additional, Schreuer, Jürgen, additional, Neuking, Klaus, additional, and Eggeler, Gunther, additional

Published
2014
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32. (Invited) Epitaxy of Direct Bandgap Group IV Si-Ge-Sn Alloys towards Heterostructure Light Emitters

Author

von, Nils, Driesch, den, Stange, Daniela, Rainko, Denis, Povstugar, Ivan, Breuer, Uwe, Ikonic, Zoran, Hartmann, Michel, Andreas, Markus, Capellini, Giovanni, Sigg, Hans, Mantl, Siegfried, Grutzmacher, Detlev, and Buca, Dan

Abstract

The recent development of optically pumped lasers made from Si-congruent GeSn alloys have strengthened the efforts to fabricate a monolithically integratable light source. Such fully Si-compatible solution may allow merging of state-of-the-art electronics with photonic components on the same chip for on-chip optical interconnects. To advance this prospering field, we investigated the epitaxy of different GeSn/SiGeSn heterostructures, based on GeSn active layers. Double heterostructures allow confinement of carriers in GeSn, though with the deleterious presence of misfit dislocations in the rather thick active regions. This can be overcome, however, in multi quantum well (MQW) structures. Microdisk resonators made from different heterostructures were fabricated, indicating enhanced properties of MQW layers. Epitaxy of in-situ doped p-i-n heterostructure diodes shows paths towards electrical carrier injection into GeSn optoelectronic devices.

Published
2018

36. Advanced Scale Bridging Microstructure Analysis of Single Crystal Ni-Base Superalloys.

Author

Parsa, Alireza B., Wollgramm, Philip, Buck, Hinrich, Somsen, Christoph, Kostka, Aleksander, Povstugar, Ivan, Choi, Pyuck‐Pa, Raabe, Dierk, Dlouhy, Antonin, Müller, Julian, Spiecker, Erdmann, Demtroder, Kathrin, Schreuer, Jürgen, Neuking, Klaus, and Eggeler, Gunther

Subjects
HEAT resistant alloys, MICROSTRUCTURE, SINGLE crystals, DENDRITIC crystals, ELECTRON probe microanalysis
Abstract

In the present work, we show how conventional and advanced mechanical, chemical, and microstructural methods can be used to characterize cast single crystal Ni-base superalloy (SX) plates across multiple length scales. Two types of microstructural heterogeneities are important, associated with the castmicrostructure (dendrites (D) and interdendritic (ID) regions - large scale heterogeneity) and with the well-known γ/γ' microstructure (small scale heterogeneity). Using electron probe microanalysis (EPMA),we can showthat elements such as Re, Co, and Cr partition to the dendrites while ID regions contain more Al, Ta, and Ti. Analytical transmission electron microscopy and atom probe tomography (APT) show that Al, Ta, and Ti partition to the γ' cubes while γ channels show higher concentrations of Co, Cr, Re, and W.We can combine large scale (EPMA) and small-scale analytical methods (APT) to obtain reasonable estimates for γ' volume fractions in the dendrites and in the ID regions. The chemical and mechanical properties of the SX plates studied in the present work are homogeneous, when they are determined from volumes with dimensions, which are significantly larger than the dendrite spacing. For the SX plates (140mm × 100mm × 20mm) studied in the present work this holds for the average chemical composition as well as for elastic behavior and local creep properties. We highlight the potential of HRTEM and APT to contribute to a better understanding of the role of dislocations during coarsening of the γ' phase and the effect of cooling rates after high temperature exposure on the microstructure. [ABSTRACT FROM AUTHOR]

Published
2015
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37. Advanced GeSn/SiGeSn Group IV Heterostructure Lasers

Author

Dan Buca, Thibaud Denneulin, Peter Zaumseil, Siegfried Mantl, Detlev Grützmacher, Jean-Michel Hartmann, Thomas Schröder, Nils von den Driesch, Zoran Ikonic, Giovanni Capellini, Ivan Povstugar, Hans Sigg, Daniela Stange, Denis Rainko, Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association, Innovations for High Performance Microelectronics (IHP), Roma Tre University, Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), University of Leeds, Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Paul Scherrer Institute (PSI), von den Driesch, Nil, Stange, Daniela, Rainko, Deni, Povstugar, Ivan, Zaumseil, Peter, Capellini, Giovanni, Schröder, Thoma, Denneulin, Thibaud, Ikonic, Zoran, Hartmann, Jean-Michel, Sigg, Han, Mantl, Siegfried, Grützmacher, Detlev, Buca, Dan, Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Photoluminescence, Materials science, General Chemical Engineering, Laser, General Physics and Astronomy, Medicine (miscellaneous), 02 engineering and technology, Epitaxy, 01 natural sciences, 7. Clean energy, Biochemistry, Genetics and Molecular Biology (miscellaneous), Electron holography, Physics and Astronomy (all), Condensed Matter::Materials Science, [SPI]Engineering Sciences [physics], Engineering (all), 0103 physical sciences, Chemical Engineering (all), General Materials Science, SiGeSn, Electronic band structure, 010302 applied physics, business.industry, General Engineering, Heterojunction, Multi-quantum well, 021001 nanoscience & nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Characterization (materials science), GeSn, heterostructures, Heterostructure, Optoelectronics, Direct and indirect band gaps, ddc:500, Materials Science (all), Photonics, 0210 nano-technology, business, lasers, multi-quantum wells
Abstract

International audience; Growth and characterization of advanced group IV semiconductor materials with CMOS-compatible applications are demonstrated, both in photonics. The investigated GeSn/SiGeSn heterostructures combine direct bandgap GeSn active layers with indirect gap ternary SiGeSn claddings, a design proven its worth already decades ago in the III-V material system. Different types of double heterostructures and multi-quantum wells (MQWs) are epitaxially grown with varying well thicknesses and barriers. The retaining high material quality of those complex structures is probed by advanced characterization methods, such as atom probe tomography and dark-field electron holography to extract composition parameters and strain, used further for band structure calculations. Special emphasis is put on the impact of carrier confinement and quantization effects, evaluated by photoluminescence and validated by theoretical calculations. As shown, particularly MQW heterostructures promise the highest potential for efficient next generation complementary metal-oxide-semiconductor (CMOS)-compatible group IV lasers.

Published
2018
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