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Large amplitude fluxional behaviour of elemental calcium under high pressure

Experimental evidences are presented showing unusually large and highly anisotropic vibrations in the “simple cubic” (SC) unit cell adopted by calcium over a broad pressure ranging from 30–90 GPa and at temperature as low as 40 K. X-ray diffraction patterns show a preferential broadening of the (110...

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Autores principales: Tse, J. S., Desgreniers, S., Ohishi, Y., Matsuoka, T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330680/
https://www.ncbi.nlm.nih.gov/pubmed/22523635
http://dx.doi.org/10.1038/srep00372
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author Tse, J. S.
Desgreniers, S.
Ohishi, Y.
Matsuoka, T.
author_facet Tse, J. S.
Desgreniers, S.
Ohishi, Y.
Matsuoka, T.
author_sort Tse, J. S.
collection PubMed
description Experimental evidences are presented showing unusually large and highly anisotropic vibrations in the “simple cubic” (SC) unit cell adopted by calcium over a broad pressure ranging from 30–90 GPa and at temperature as low as 40 K. X-ray diffraction patterns show a preferential broadening of the (110) Bragg reflection indicating that the atomic displacements are not isotropic but restricted to the [110] plane. The unusual observation can be rationalized invoking a simple chemical perspective. As the result of pressure-induced s → d transition, Ca atoms situated in the octahedral environment of the simple cubic structure are subjected to Jahn-Teller distortions. First-principles molecular dynamics calculations confirm this suggestion and show that the distortion is of dynamical nature as the cubic unit cell undergoes large amplitude tetragonal fluctuations. The present results show that, even under extreme compression, the atomic configuration is highly fluxional as it constantly changes.
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spelling pubmed-33306802012-04-20 Large amplitude fluxional behaviour of elemental calcium under high pressure Tse, J. S. Desgreniers, S. Ohishi, Y. Matsuoka, T. Sci Rep Article Experimental evidences are presented showing unusually large and highly anisotropic vibrations in the “simple cubic” (SC) unit cell adopted by calcium over a broad pressure ranging from 30–90 GPa and at temperature as low as 40 K. X-ray diffraction patterns show a preferential broadening of the (110) Bragg reflection indicating that the atomic displacements are not isotropic but restricted to the [110] plane. The unusual observation can be rationalized invoking a simple chemical perspective. As the result of pressure-induced s → d transition, Ca atoms situated in the octahedral environment of the simple cubic structure are subjected to Jahn-Teller distortions. First-principles molecular dynamics calculations confirm this suggestion and show that the distortion is of dynamical nature as the cubic unit cell undergoes large amplitude tetragonal fluctuations. The present results show that, even under extreme compression, the atomic configuration is highly fluxional as it constantly changes. Nature Publishing Group 2012-04-20 /pmc/articles/PMC3330680/ /pubmed/22523635 http://dx.doi.org/10.1038/srep00372 Text en Copyright © 2012, Macmillan Publishers Limited. All rights reserved http://creativecommons.org/licenses/by-nc-nd/3.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
spellingShingle Article
Tse, J. S.
Desgreniers, S.
Ohishi, Y.
Matsuoka, T.
Large amplitude fluxional behaviour of elemental calcium under high pressure
title Large amplitude fluxional behaviour of elemental calcium under high pressure
title_full Large amplitude fluxional behaviour of elemental calcium under high pressure
title_fullStr Large amplitude fluxional behaviour of elemental calcium under high pressure
title_full_unstemmed Large amplitude fluxional behaviour of elemental calcium under high pressure
title_short Large amplitude fluxional behaviour of elemental calcium under high pressure
title_sort large amplitude fluxional behaviour of elemental calcium under high pressure
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330680/
https://www.ncbi.nlm.nih.gov/pubmed/22523635
http://dx.doi.org/10.1038/srep00372
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