Structures and energetics of Ga2O3 polymorphs

Satoru Yoshioka, H. Hayashi, A. Kuwabara, F. Oba, K. Matsunaga, I. Tanaka

Research output: Contribution to journalArticle

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Abstract

First-principles calculations are made for five Ga2O3 polymorphs. The structure of ε-Ga2O3 with the space group Pna 21 (No.33, orthorhombic), which is sometimes called κ-Ga2O3 in the literature, is consistent with experimental reports. The structure of γ-Ga2O3 is optimized within 14 inequivalent configurations of defective spinel structures. Phonon dispersion curves of four polymorphs are obtained. The volume expansivity, bulk modulus, and specific heat at constant volume are computed as a function of temperature within the quasi-harmonic approximation. The Helmholtz free energies of the polymorphs are thus compared. The expansivity shows a relationship of β<ε<α<δ, while β<ε<δ<α for the bulk modulus. The formation free energies have the tendency β<ε<α<δ<γ at low temperatures. With the increase of temperature, the difference in free energy between the β-phase and the ε-phase becomes smaller. Eventually the ε phase becomes more stable at above 1600K.

Original languageEnglish
Article number346211
JournalJournal of Physics Condensed Matter
Volume19
Issue number34
DOIs
Publication statusPublished - Aug 29 2007

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Polymorphism
Free energy
free energy
bulk modulus
Elastic moduli
Temperature
Specific heat
spinel
tendencies
specific heat
harmonics
temperature
curves
configurations
approximation

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Yoshioka, S., Hayashi, H., Kuwabara, A., Oba, F., Matsunaga, K., & Tanaka, I. (2007). Structures and energetics of Ga2O3 polymorphs. Journal of Physics Condensed Matter, 19(34), [346211]. https://doi.org/10.1088/0953-8984/19/34/346211

Structures and energetics of Ga2O3 polymorphs. / Yoshioka, Satoru; Hayashi, H.; Kuwabara, A.; Oba, F.; Matsunaga, K.; Tanaka, I.

In: Journal of Physics Condensed Matter, Vol. 19, No. 34, 346211, 29.08.2007.

Research output: Contribution to journalArticle

Yoshioka, S, Hayashi, H, Kuwabara, A, Oba, F, Matsunaga, K & Tanaka, I 2007, 'Structures and energetics of Ga2O3 polymorphs', Journal of Physics Condensed Matter, vol. 19, no. 34, 346211. https://doi.org/10.1088/0953-8984/19/34/346211
Yoshioka, Satoru ; Hayashi, H. ; Kuwabara, A. ; Oba, F. ; Matsunaga, K. ; Tanaka, I. / Structures and energetics of Ga2O3 polymorphs. In: Journal of Physics Condensed Matter. 2007 ; Vol. 19, No. 34.
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