Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re σ-phase
- ICAMS, Ruhr University Bochum, Universität Str. 150, D-44801 Bochum (Germany)
- SIMAP, UMR CNRS-INPG-UJF 5266, BP 75, F-38402 Saint Martin d’Hères (France)
- Department of Earth Sciences, Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre-UCL, University College London, Gower Street, London WC1E 6BT (United Kingdom)
Using density-functional theory in combination with the direct force method and molecular dynamics we investigate the vibrational properties of a binary Cr-Re σ-phase. In the harmonic approximation, we have computed phonon dispersion curves and density of states, evidencing structural and chemical effects. We found that the σ-phase is mechanically unstable in some configurations, for example, when all crystallographic sites are occupied by Re atoms. By using a molecular-dynamics-based method, we have analysed the anharmonicity in the system and found negligible effects (∼0.5 kJ/mol) on the Helmholtz energy of the binary Cr-Re σ-phase up to 2000 K (∼0.8T{sub m}). Finally, we show that the vibrational contribution has significant consequences on the disordering of the σ-phase at high temperature.
- OSTI ID:
- 22253294
- Journal Information:
- Journal of Chemical Physics, Vol. 140, Issue 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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