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Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure

High-pressure phase stabilities up to 600 K and the related properties of Na(2)O(2) under pressures up to 300 GPa were investigated using first-principles calculations and the quasi-harmonic approximation. Two high-pressure phases of Na(2)O(2) that are thermodynamically and dynamically stable were p...

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Autores principales: Jimlim, Pornmongkol, Tsuppayakorn-aek, Prutthipong, Pakornchote, Teerachote, Ektarawong, Annop, Pinsook, Udomsilp, Bovornratanaraks, Thiti
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9072567/
https://www.ncbi.nlm.nih.gov/pubmed/35529358
http://dx.doi.org/10.1039/c9ra03735g
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author Jimlim, Pornmongkol
Tsuppayakorn-aek, Prutthipong
Pakornchote, Teerachote
Ektarawong, Annop
Pinsook, Udomsilp
Bovornratanaraks, Thiti
author_facet Jimlim, Pornmongkol
Tsuppayakorn-aek, Prutthipong
Pakornchote, Teerachote
Ektarawong, Annop
Pinsook, Udomsilp
Bovornratanaraks, Thiti
author_sort Jimlim, Pornmongkol
collection PubMed
description High-pressure phase stabilities up to 600 K and the related properties of Na(2)O(2) under pressures up to 300 GPa were investigated using first-principles calculations and the quasi-harmonic approximation. Two high-pressure phases of Na(2)O(2) that are thermodynamically and dynamically stable were predicted consisting of the Amm2 (distorted P6̄2m) and the P2(1)/c structures, which are stable at low temperature in the pressure range of 0–22 GPa and 22–28 GPa, respectively. However, the P6̄2m and Pbam structures become the most stable instead of the Amm2 and P2(1)/c structures at the elevated temperatures, respectively. Interestingly, the softening of some phonon modes and the decreasing of some elastic stiffnesses in the Amm2 structure were also predicted in the pressure ranges of 2–3 GPa and 9–10 GPa. This leads to the decreasing of phonon free energy and the increasing of the ELF value in the same pressure ranges. The HSE06 band gaps suggest that all phases are insulators, and they increase with increasing pressure. Our findings provide the P–T phase diagram of Na(2)O(2), which may be useful for investigating the thermodynamic properties and experimental verification.
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spelling pubmed-90725672022-05-06 Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure Jimlim, Pornmongkol Tsuppayakorn-aek, Prutthipong Pakornchote, Teerachote Ektarawong, Annop Pinsook, Udomsilp Bovornratanaraks, Thiti RSC Adv Chemistry High-pressure phase stabilities up to 600 K and the related properties of Na(2)O(2) under pressures up to 300 GPa were investigated using first-principles calculations and the quasi-harmonic approximation. Two high-pressure phases of Na(2)O(2) that are thermodynamically and dynamically stable were predicted consisting of the Amm2 (distorted P6̄2m) and the P2(1)/c structures, which are stable at low temperature in the pressure range of 0–22 GPa and 22–28 GPa, respectively. However, the P6̄2m and Pbam structures become the most stable instead of the Amm2 and P2(1)/c structures at the elevated temperatures, respectively. Interestingly, the softening of some phonon modes and the decreasing of some elastic stiffnesses in the Amm2 structure were also predicted in the pressure ranges of 2–3 GPa and 9–10 GPa. This leads to the decreasing of phonon free energy and the increasing of the ELF value in the same pressure ranges. The HSE06 band gaps suggest that all phases are insulators, and they increase with increasing pressure. Our findings provide the P–T phase diagram of Na(2)O(2), which may be useful for investigating the thermodynamic properties and experimental verification. The Royal Society of Chemistry 2019-10-01 /pmc/articles/PMC9072567/ /pubmed/35529358 http://dx.doi.org/10.1039/c9ra03735g Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/
spellingShingle Chemistry
Jimlim, Pornmongkol
Tsuppayakorn-aek, Prutthipong
Pakornchote, Teerachote
Ektarawong, Annop
Pinsook, Udomsilp
Bovornratanaraks, Thiti
Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
title Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
title_full Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
title_fullStr Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
title_full_unstemmed Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
title_short Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
title_sort theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9072567/
https://www.ncbi.nlm.nih.gov/pubmed/35529358
http://dx.doi.org/10.1039/c9ra03735g
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