First-principles lattice dynamics and thermodynamic properties of α-, θ-, κ- and γ-Al2O3 and solid state temperature-pressure phase diagram

Hongling Zhou, Yanzhou Ji, Yi Wang, Keqin Feng, Baifeng Luan, Xueyou Zhang, Long Qing Chen

Research output: Contribution to journalArticlepeer-review

Abstract

γ-Al2O3 is a commonly observed high temperature alumina phase during Al-based alloy oxidation. Due to the partially ordered, defective nature of the spinel structure arising from the partial occupancy in the Al sites, first-principles prediction of the thermodynamic properties of γ-Al2O3 has been challenging. In this work, employing the first-principles quasiharmonic approach, we obtain the finite temperature thermodynamic properties of γ-Al2O3, including entropy, chemical potential, heat capacity, thermal expansion coefficient, and elastic constants and the results are compared with those calculated for the other three alumina phases, i.e., α-Al2O3, θ-Al2O3, and κ-Al2O3. The calculated lattice constants and the predicted relative phase stability under 0 K and 0 GPa, α>κ>θ>γ, are consistent with experimental values and existing calculations, respectively. Based on the results, we constructed the temperature-pressure phase diagram covering the four Al2O3 phases (α, κ, θ, γ), which could provide for experimentally synthesizing the different alumina phases.

Original languageEnglish (US)
Article number119513
JournalActa Materialia
Volume263
DOIs
StatePublished - Jan 15 2024

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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