First-principles study of structural stability, elastic, vibrational, and electronic properties of TaRu alloys
Institute of Modern Physics, Northwest University - Xi'an 710069, PRC
2 College of Chemistry and Materials Science, Northwest University - Xi'an 710069, PRC
3 Department of Electronic Science, Northwest University - Xi'an 710069, PRC
Accepted: 16 May 2011
The structural stability, electronic structure, elastic constants and vibrational properties of TaRu β (cubic), β ′ (tetragonal) and β ″ (orthorhombic) phases have been studied using density functional theory. It is found that the β-to-β ′ phase transformation is closely related to the elastic properties. The β ′ phase exhibits an unstable phonon at the R point (0 1/2 1/2), which induces the transition from the high-symmetry β ′ phase to the low-symmetry β ″ phase. The β ″ phase is obtained for the first time from first-principles calculations and the lattice parameters agree very well with the experimental data. The total density of states at the Fermi level and the phonon dispersion relations indicate that the β and β ′ phase are unstable, whereas the β ″ phase is the most stable structure.
PACS: 81.30.Kf – Martensitic transformations / 63.20.Ry – Anharmonic lattice modes / 62.20.fg – Shape-memory effect; yield stress; superelasticity
© EPLA, 2011