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High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure

Magnesium chloride (MgCl(2)) with the rhombohedral layered CdCl(2)-type structure (α-MgCl(2)) has been studied experimentally using synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy using a diamond-anvil cell up to 100 GPa at room temperature and theoretically using first-...

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Autores principales: Stavrou, Elissaios, Yao, Yansun, Zaug, Joseph M., Bastea, Sorin, Kalkan, Bora, Konôpková, Zuzana, Kunz, Martin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4981878/
https://www.ncbi.nlm.nih.gov/pubmed/27515116
http://dx.doi.org/10.1038/srep30631
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author Stavrou, Elissaios
Yao, Yansun
Zaug, Joseph M.
Bastea, Sorin
Kalkan, Bora
Konôpková, Zuzana
Kunz, Martin
author_facet Stavrou, Elissaios
Yao, Yansun
Zaug, Joseph M.
Bastea, Sorin
Kalkan, Bora
Konôpková, Zuzana
Kunz, Martin
author_sort Stavrou, Elissaios
collection PubMed
description Magnesium chloride (MgCl(2)) with the rhombohedral layered CdCl(2)-type structure (α-MgCl(2)) has been studied experimentally using synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy using a diamond-anvil cell up to 100 GPa at room temperature and theoretically using first-principles density functional calculations. The results reveal a pressure-induced second-order structural phase transition to a hexagonal layered CdI(2)-type structure (β-MgCl(2)) at 0.7 GPa: the stacking sequence of the Cl anions are altered resulting in a reduction of the c-axis length. Theoretical calculations confirm this phase transition sequence and the calculated transition pressure is in excellent agreement with the experiment. Lattice dynamics calculations also reproduce the experimental Raman spectra measured for the ambient and high-pressure phase. According to our experimental results MgCl(2) remains in a 2D layered phase up to 100 GPa and further, the 6-fold coordination of Mg cations is retained. Theoretical calculations of relative enthalpy suggest that this extensive pressure stability is due to a low enthalpy of the layered structure ruling out kinetic barrier effects. This observation is unusual, as it contradicts with the general structural behavior of highly compressed AB(2) compounds.
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spelling pubmed-49818782016-08-19 High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure Stavrou, Elissaios Yao, Yansun Zaug, Joseph M. Bastea, Sorin Kalkan, Bora Konôpková, Zuzana Kunz, Martin Sci Rep Article Magnesium chloride (MgCl(2)) with the rhombohedral layered CdCl(2)-type structure (α-MgCl(2)) has been studied experimentally using synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy using a diamond-anvil cell up to 100 GPa at room temperature and theoretically using first-principles density functional calculations. The results reveal a pressure-induced second-order structural phase transition to a hexagonal layered CdI(2)-type structure (β-MgCl(2)) at 0.7 GPa: the stacking sequence of the Cl anions are altered resulting in a reduction of the c-axis length. Theoretical calculations confirm this phase transition sequence and the calculated transition pressure is in excellent agreement with the experiment. Lattice dynamics calculations also reproduce the experimental Raman spectra measured for the ambient and high-pressure phase. According to our experimental results MgCl(2) remains in a 2D layered phase up to 100 GPa and further, the 6-fold coordination of Mg cations is retained. Theoretical calculations of relative enthalpy suggest that this extensive pressure stability is due to a low enthalpy of the layered structure ruling out kinetic barrier effects. This observation is unusual, as it contradicts with the general structural behavior of highly compressed AB(2) compounds. Nature Publishing Group 2016-08-12 /pmc/articles/PMC4981878/ /pubmed/27515116 http://dx.doi.org/10.1038/srep30631 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Stavrou, Elissaios
Yao, Yansun
Zaug, Joseph M.
Bastea, Sorin
Kalkan, Bora
Konôpková, Zuzana
Kunz, Martin
High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure
title High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure
title_full High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure
title_fullStr High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure
title_full_unstemmed High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure
title_short High-pressure X-ray diffraction, Raman, and computational studies of MgCl(2) up to 1 Mbar: Extensive pressure stability of the β-MgCl(2) layered structure
title_sort high-pressure x-ray diffraction, raman, and computational studies of mgcl(2) up to 1 mbar: extensive pressure stability of the β-mgcl(2) layered structure
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4981878/
https://www.ncbi.nlm.nih.gov/pubmed/27515116
http://dx.doi.org/10.1038/srep30631
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