Details

Autor(en) / Beteiligte

• Palumbo, Mauro
• Fries, Suzana G
• Pasturel, Alain
• Alfè, Dario

Titel

Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re σ-phase

Ist Teil von

• The Journal of chemical physics, 2014-04, Vol.140 (14), p.144502-144502

Ort / Verlag

United States: American Institute of Physics

Erscheinungsjahr

2014

Quelle

AIP Journals (American Institute of Physics)

Beschreibungen/Notizen

• 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(m)). Finally, we show that the vibrational contribution has significant consequences on the disordering of the σ-phase at high temperature.