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Structural-Stability Study of Antiperovskite Na3O⁢Cl for Na-Rich Solid Electrolyte

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Abstract
The structural phase transition of the high-symmetry cubic phase of antiperovskite Na3O⁢Cl is investigated by computing the phonon band structures of 14 different polymorphs with distinct types of O⁢Na6 octahedral tilting. The resulting P-T phase diagram shows that, at high temperature and low pressure, the high-symmetry cubic structure with Pm⁢¯3m symmetry is the most stable phase. At low temperature and high pressure, on the other hand, the monoclinic structure with P⁢21/m symmetry becomes the most stable phase. In between those two, there is a region in the phase diagram where the orthorhombic structure with Bmmb symmetry is the most stable phase. To improve upon the quasiharmonic results, we do additional calculations in the framework of the self-consistent phonon (SCP) theory, including lattice anharmonicity by using cubic and quartic interatomic force constants (IFCs). This is particularly important for the high-symmetry cubic phase. We find that by decreasing the temperature, the frequency of the soft phonon at the M and R symmetry points gradually shifts to lower values. From these results, we can infer that a phase transition occurs around 166-195 K upon soft-mode condensation. Due to the proximity of the soft-mode frequencies at both symmetry points R and M, we expect a cubic-to-orthorhombic phase transition to be realized via simultaneous condensation of the two octahedral tilting modes.
Issued Date
2023
Tan-Lien Pham
Woon Ih Choi
Aamir Shafique
Hye Jung Kim
Munbo Shim
Kyoungmin Min
Won-Joon Son
Inkook Jang
Dae Sin Kim
Mauro Boero
Carlo Massobrio
Guido Ori
Hyo Sug Lee
Young-Han Shin
Type
Article
Keyword
Physical sciencesPhysics
DOI
10.1103/PhysRevApplied.19.034004
URI
https://oak.ulsan.ac.kr/handle/2021.oak/17633
Publisher
PHYSICAL REVIEW APPLIED
Language
영어
ISSN
2331-7019
Citation Volume
19
Citation Number
3
Citation Start Page
1
Citation End Page
11
Appears in Collections:
Natural Science > ETC
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