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Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re σ-phase
- Source :
- Journal of Chemical Physics, Journal of Chemical Physics, American Institute of Physics, 2014, 140 (14), ⟨10.1063/1.4869800⟩
- Publication Year :
- 2014
-
Abstract
- International audience; Using density-functional theory in combination with the direct force method and molecular dynamics we investigate the vibrational properties of a binary Cr-Re sigma-phase. In the harmonic approximation, we have computed phonon dispersion curves and density of states, evidencing structural and chemical effects. We found that the s-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 (similar to 0.5 kJ/mol) on the Helmholtz energy of the binary Cr-Re sigma-phase up to 2000 K (similar to 0.8T(m)). Finally, we show that the vibrational contribution has significant consequences on the disordering of the sigma-phase at high temperature. (C) 2014 AIP Publishing LLC.
- Subjects :
- Chemistry
Phonon
Anharmonicity
General Physics and Astronomy
Thermodynamics
[CHIM.MATE]Chemical Sciences/Material chemistry
Molecular dynamics
symbols.namesake
Helmholtz free energy
Phase (matter)
Molecular vibration
symbols
Density of states
Physical chemistry
Density functional theory
Physical and Theoretical Chemistry
Subjects
Details
- ISSN :
- 10897690 and 00219606
- Volume :
- 140
- Issue :
- 14
- Database :
- OpenAIRE
- Journal :
- The Journal of chemical physics
- Accession number :
- edsair.doi.dedup.....196cf947d299ebbbc2170773a51be2b6