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Your search keyword '"Beran, Premysl"' showing total 102 results
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102 results on '"Beran, Premysl"'

1. The Crystal Structure of Al4SiC4 Revisited

Author

Ong, Chin Shen, primary, Donzel-Gargand, Olivier, additional, Berastegui, Pedro, additional, Cedervall, Johan, additional, Bayrak Pehlivan, Ilknur, additional, Hervoches, Charles, additional, Beran, Premysl, additional, Edvinsson, Tomas, additional, Eriksson, Olle, additional, and Jansson, Ulf, additional

Published
2024
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5. Magnetic structure of the magnetocaloric compound AlFe2B2

Author

Cedervall, Johan, Andersson, Mikael Svante, Sarkar, Tapati, Delczeg-Czirjak, Erna K., Bergqvist, Lars, Hansen, Thomas C., Beran, Premysl, Nordblad, Per, and Sahlberg, Martin

Subjects
Condensed Matter - Materials Science
Abstract

The crystal and magnetic structures of AlFe2B2 have been studied with a combination of X-ray and neutron diffraction and electronic structure calculations. The magnetic and magnetocaloric properties have been investigated by magnetisation measurements. The samples have been produced using high temperature synthesis and subsequent heat treatments. The compound crystallises in the orthorhombic crystal system Cmmm and it orders ferromagnetically at 285 K through a second order phase transition. At temperatures below the magnetic transition the magnetic moments align along the crystallographic $a$-axis. The magnetic entropy change from 0 to 800 kA/m was found to be -1.3 J/K kg at the magnetic transition temperature.

Published
2016
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7. The crystal and magnetic structure of the magnetocaloric compound FeMnP0.5Si0.5

Author

Höglin, Viktor, Hudl, Matthias, Sahlberg, Martin, Nordblad, Per, Beran, Premysl, and Andersson, Yvonne

Subjects
Condensed Matter - Materials Science
Abstract

The crystal and magnetic structure of the magnetocaloric compound FeMnP0.5Si0.5 have been studied by means of neutron and X-ray powder diffraction. Single phase samples of nominal composition FeMnP0.5Si0.5 have been prepared by the drop synthesis method. The compound crystallizes in the Fe2P-type structure (P-62m) with the magnetic moments aligned along the aaxis. It is found that the Fe atoms are mainly situated in the tetrahedral 3g site while the Mn atoms prefer the pyramidal 3f position. The material is ferromagnetic (TC = 382 K) and at 296 K the total magnetic moment is 4.4 \mu B/f.u. It is shown that the magnetic moment in the 3f site is larger (2.5 \mu B) than in the 3g site (1.9 \mu B)., Comment: 8 pages, 4 figures

Published
2011
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8. A new material for hydrogen storage, ScAl0.8Mg0.2

Author

Sahlberg, Martin, Beran, Premysl, Nielsen, Thomas Kollin, Cerenius, Yngve, Kadas, Krisztina, Vitos, Levente, Eriksson, Olle, Jensen, Torben R, and Andersson, Yvonne

Subjects
Condensed Matter - Materials Science
Abstract

A novel aluminium rich alloy for hydrogen storage has been discovered, ScAl0.8Mg0.2, which has superior properties regarding hydrogen storage capacity, kinetics and stability towards air oxidation in comparison to hydrogen absorption in state-of-the-art intermetallic compounds. Detailed analysis of the hydrogen absorption in ScAl0.8Mg0.2 has been performed using in situ synchrotron radiation powder X-ray diffraction, neutron powder diffraction and quantum mechanical calculations. The results from calculations and experiments are in good agreement with each other.

Published
2009
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19. Effect of pseudo-Tsai cluster incorporation on the magnetic structures of R−Au−Si (R=Tb,Ho) quasicrystal approximants

Author

Gebresenbut, Girma Hailu, primary, Shiino, Takayuki, additional, Andersson, Mikael Svante, additional, Qureshi, Navid, additional, Fabelo, Oscar, additional, Beran, Premysl, additional, Qvarngård, Daniel, additional, Henelius, Patrik, additional, Rydh, Andreas, additional, Mathieu, Roland, additional, Nordblad, Per, additional, and Pay Gomez, Cesar, additional

Published
2022
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20. Revealing the Magnetic Structure and Properties of Mn(Co,Ge)2

Author

Larsen, Simon R., primary, Shtender, Vitalii, additional, Hedlund, Daniel, additional, Delczeg-Czirjak, Erna K., additional, Beran, Premysl, additional, Cedervall, Johan, additional, Vishina, Alena, additional, Hansen, Thomas C., additional, Herper, Heike C., additional, Svedlindh, Peter, additional, Eriksson, Olle, additional, and Sahlberg, Martin, additional

Published
2022
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23. Effect of pseudo-Tsai cluster incorporation on the magnetic structures of R-Au-Si (R = Tb, Ho) quasicrystal approximants

Author

Gebresenbut, Girma Hailu, Shiino, Takayuki, Andersson, Mikael Svante, Qureshi, Navid, Fabelo, Oscar, Beran, Premysl, Qvarngard, Daniel, Henelius, Patrik, Rydh, Andreas, Mathieu, Roland, Nordblad, Per, and Pay Gómez, Cesar

Subjects
Condensed Matter Physics, Den kondenserade materiens fysik
Abstract

In cluster-based quasicrystals, tetrahedra located in conventional Tsai clusters may be replaced by single rare-earth (R) ions at the cluster centers (pseudo-Tsai clusters). In this study, we investigate the effect of the pseudo-Tsai cluster incorporation on the magnetic structures of two approximants, the Tsai-type Tb-Au-Si [denoted TAS(0)] and Ho-Au-Si [denoted HAS(52)] with partial replacement of conventional Tsai clusters by pseudo-Tsai clusters, up to 52%. The mixture of Tsai and pseudo-Tsai clusters can be considered a different source of randomness/disorder other than the conventional chemical mix sites (Au/Si). The effect of the latter has been previously discussed regarding the origin/cause of spin-glass-like ordering and Anderson localization of electronic states in quasicrystals and approximant crystals. Single crystal neutron diffraction experiments at 2 K were performed and bulk physical properties (magnetization and specific heat) were investigated. In addition, earlier collected powder neutron diffraction data of TAS(14) with 14% replacement was reanalyzed in light of the results on TAS(0) and HAS(52). We find that the arrangement of ordered magnetic spins in the icosahedral shells of these phases is similar, while the cluster-center R magnetic states are different. In the case of TAS(14), the cluster-center Tb magnetic moments seem to affect the arrangement of surrounding icosahedral magnetic moments, and the magnetic structure of the icosahedral shell deviates from that of TAS(0). In the case of HAS(52), however, the icosahedral R magnetic moments are less affected by the cluster-center R, while the averaged cluster-center R magnetic moments are significantly diminished. We discuss these results considering the magnetic ordering effect on the bulk physical properties.

Published
2022

28. Dynamic Structure Evolution of Extensively Delithiated High Voltage Spinel Li1+xNi0.5Mn1.5O4x< 1.5

Author

Jobst, Nicola M., Paul, Neelima, Beran, Premysl, Mancini, Marilena, Gilles, Ralph, Wohlfahrt-Mehrens, Margret, and Axmann, Peter

Abstract

High voltage spinel is one of the most promising next-generation cobalt-free cathode materials for lithium ion battery applications. Besides the typically utilized compositional range of LixNi0.5Mn1.5O4 0 < x< 1 in the voltage window of 4.90–3.00 V, additional 1.5 mol of Li per formula unit can be introduced into the structure, in an extended voltage range to 1.50 V. Theoretically, this leads to significant increase of the specific energy from 690 to 1190 Wh/kg. However, utilization of the extended potential window leads to rapid capacity fading and voltage polarization that lack a comprehensive explanation. In this work, we conducted potentiostatic entropymetry, operando XRD and neutron diffraction on the ordered stoichiometric spinel LixNi0.5Mn1.5O4within 0 < x< 2.5 in order to understand the dynamic structure evolution and correlate it with the voltage profile. During the two-phase reaction from cubic (x< 1) to tetragonal (x> 1) phase at ∼2.8 V, we identified the evolution of a second tetragonal phase with x> 2. The structural evaluation during the delithiation indicates the formation of an intermediate phase with cubic symmetry at a lithium content of x= 1.5. Evaluation of neutron diffraction data, with maximum entropy method, of the highly lithiated phase LixNi0.5Mn1.5O4with 2 < x< 2.5 strongly suggests that lithium ions are located on octahedral 8a and tetrahedral 4a positions of the distorted tetragonal phase I41amd. Consequently, we were able to provide a conclusive explanation for the additional voltage step at 2.10 V, the sloping voltage profile below 1.80 V, and the additional voltage step at ∼3.80 V.

Published
2023
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34. Magnetic structure of the magnetocaloric compound AlFe2B2

Author

Cedervall, Johan, primary, Andersson, Mikael Svante, additional, Sarkar, Tapati, additional, Delczeg-Czirjak, Erna K., additional, Bergqvist, Lars, additional, Hansen, Thomas C., additional, Beran, Premysl, additional, Nordblad, Per, additional, and Sahlberg, Martin, additional

Published
2016
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36. A new material hydrogen storage; ScAl0.8Mg0.2

Author

Sahlberg, Martin, Beran, Premysl, Nielsen, Thomas Kollin, Cerenius, Yngve, Kadas, Krisztina, P.J. Punkkinen, Marko, Vitos, Levente, Eriksson, Olle, Jensen, Torben René, and Andersson, Yvonne

Abstract

Udgivelsesdato: 6/9 2009

Published
2009

40. A new material for hydrogen storage; ScAl0.8Mg0.2

Author

Sahlberg, Martin, primary, Beran, Premysl, additional, Nielsen, Thomas Kollin, additional, Cerenius, Yngve, additional, Kadás, Krisztina, additional, Punkkinen, Marko P.J., additional, Vitos, Levente, additional, Eriksson, Olle, additional, Jensen, Torben R., additional, and Andersson, Yvonne, additional

Published
2009
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42. A new material for hydrogen storage; ScAl0.8Mg0.2

Author

Sahlberg, Martin, Beran, Premysl, Nielsen, Thomas Kollin, Cerenius, Yngve, Kadás, Krisztina, Punkkinen, Marko P.J., Vitos, Levente, Eriksson, Olle, Jensen, Torben R., and Andersson, Yvonne

Subjects
*SCANDIUM, *HYDROGEN, *ALUMINUM alloys, *CHEMICAL kinetics, *OXIDATION, *GAS absorption & adsorption, *INTERMETALLIC compounds, *COMPARATIVE studies
Abstract

Abstract: A novel aluminium rich alloy for hydrogen storage has been discovered, ScAl0.8Mg0.2, which has very promising properties regarding hydrogen storage capacity, kinetics and stability towards air oxidation in comparison to hydrogen absorption in state-of-the-art intermetallic compounds. The absorption of hydrogen was found to be very fast, even without adding any catalyst, and reversible. The discovered alloy crystallizes in a CsCl-type structure, but decomposes to ScH2 and Al(Mg) during hydrogen absorption. Detailed analysis of the hydrogen absorption in ScAl0.8Mg0.2 has been performed using in situ synchrotron radiation powder X-ray diffraction, neutron powder diffraction and quantum mechanical calculations. The results from theory and experiments are in good agreement with each other. [Copyright &y& Elsevier]

Published
2009
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43. Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1−xScx)2∕3W1∕3O3 solid solutions.

Author

Ivanov, Sergey A., Beran, Premysl, Bush, Alexandr A., Sarkar, Tapati, Shafeie, Samrand, Wang, Duo, Sanyal, Biplab, Eriksson, Olle, Sahlberg, Martin, Kvashnin, Yaroslav, Tellgren, Roland, Nordblad, Per, and Mathieu, Roland

Subjects
*SOLID solutions, *FERRIMAGNETIC materials, *CATIONS, *NEUTRON diffraction, *DIFFRACTION patterns, *RIETVELD refinement, *TEMPERATURE control
Abstract

Ceramic samples of the multiferroic perovskite Pb(Fe1−xScx)2∕3W1∕3O3 with 0 ≤ x ≤ 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (Fm3̅m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B′ and B′′ sites. As the non-magnetic Sc3+ ions replace the magnetic Fe3+ cations, the antiferromagnetic state of PbFe2∕3W1∕3O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B′ and B′′ sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1−xScx)2∕3W1∕3O3 and possibly also in the undoped PbFe2∕3W1∕3O3. [ABSTRACT FROM AUTHOR]

Published
2019
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