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First Principles Theory of the hcp-fcc Phase Transition in Cobalt

Identifying the forces that drive a phase transition is always challenging. The hcp-fcc phase transition that occurs in cobalt at ~700 K has not yet been fully understood, although early theoretical studies have suggested that magnetism plays a main role in the stabilization of the fcc phase at high...

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Autores principales: Lizárraga, Raquel, Pan, Fan, Bergqvist, Lars, Holmström, Erik, Gercsi, Zsolt, Vitos, Levente
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5476570/
https://www.ncbi.nlm.nih.gov/pubmed/28630476
http://dx.doi.org/10.1038/s41598-017-03877-5
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author Lizárraga, Raquel
Pan, Fan
Bergqvist, Lars
Holmström, Erik
Gercsi, Zsolt
Vitos, Levente
author_facet Lizárraga, Raquel
Pan, Fan
Bergqvist, Lars
Holmström, Erik
Gercsi, Zsolt
Vitos, Levente
author_sort Lizárraga, Raquel
collection PubMed
description Identifying the forces that drive a phase transition is always challenging. The hcp-fcc phase transition that occurs in cobalt at ~700 K has not yet been fully understood, although early theoretical studies have suggested that magnetism plays a main role in the stabilization of the fcc phase at high temperatures. Here, we perform a first principles study of the free energies of these two phases, which we break into contributions arising from the vibration of the lattice, electronic and magnetic systems and volume expansion. Our analysis of the energy of the phases shows that magnetic effects alone cannot drive the fcc-hcp transition in Co and that the largest contribution to the stabilization of the fcc phase comes from the vibration of the ionic lattice. By including all the contributions to the free energy considered here we obtain a theoretical transition temperature of 825 K.
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spelling pubmed-54765702017-06-23 First Principles Theory of the hcp-fcc Phase Transition in Cobalt Lizárraga, Raquel Pan, Fan Bergqvist, Lars Holmström, Erik Gercsi, Zsolt Vitos, Levente Sci Rep Article Identifying the forces that drive a phase transition is always challenging. The hcp-fcc phase transition that occurs in cobalt at ~700 K has not yet been fully understood, although early theoretical studies have suggested that magnetism plays a main role in the stabilization of the fcc phase at high temperatures. Here, we perform a first principles study of the free energies of these two phases, which we break into contributions arising from the vibration of the lattice, electronic and magnetic systems and volume expansion. Our analysis of the energy of the phases shows that magnetic effects alone cannot drive the fcc-hcp transition in Co and that the largest contribution to the stabilization of the fcc phase comes from the vibration of the ionic lattice. By including all the contributions to the free energy considered here we obtain a theoretical transition temperature of 825 K. Nature Publishing Group UK 2017-06-19 /pmc/articles/PMC5476570/ /pubmed/28630476 http://dx.doi.org/10.1038/s41598-017-03877-5 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Lizárraga, Raquel
Pan, Fan
Bergqvist, Lars
Holmström, Erik
Gercsi, Zsolt
Vitos, Levente
First Principles Theory of the hcp-fcc Phase Transition in Cobalt
title First Principles Theory of the hcp-fcc Phase Transition in Cobalt
title_full First Principles Theory of the hcp-fcc Phase Transition in Cobalt
title_fullStr First Principles Theory of the hcp-fcc Phase Transition in Cobalt
title_full_unstemmed First Principles Theory of the hcp-fcc Phase Transition in Cobalt
title_short First Principles Theory of the hcp-fcc Phase Transition in Cobalt
title_sort first principles theory of the hcp-fcc phase transition in cobalt
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5476570/
https://www.ncbi.nlm.nih.gov/pubmed/28630476
http://dx.doi.org/10.1038/s41598-017-03877-5
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