First-principles study of structural stability, elastic, vibrational, and electronic properties of TaRu alloys

¹ 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

^a jiangzy@nwu.edu.cn

Received: 25 March 2011
Accepted: 16 May 2011

Abstract

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.