Structural and Electronic Properties of Ta2O5 with One Formula Unit

Abstract: Based on particle swarm optimization (PSO) algorithm and density functional theory (DFT) calculations, we identify a stable triclinic crystal structure of Ta2O5 (named as {\gamma}1-Ta2O5) at atmospheric pressure whose unit cell contains one formula unit (Z=1). Comparison with the Z=1 Ta2O5 structures from the Materials Project [APL Mater. 1, 011002 (2013)] reveals that {\gamma}1-Ta2O5 is energetically the most stable among the Z=1 Ta2O5 phases, and is the second most stable among all the Ta2O5 phases. Characterization of {\gamma}1-Ta2O5 is carried out by analyzing the X-ray powder diffraction patterns, the elastic, vibrational, thermal and electronic properties. The electronic structures of {\gamma}1-Ta2O5 are calculated using standard DFT as well as many-body perturbation theory within the GW approximation. The results indicate that {\gamma}1-Ta2O5 is a wide band gap semiconductor with an indirect gap of ~ 3.361 eV.