First-principles study of structural stability and electronic structure of La-doped Sr1.9375La0.0625TiO3.968 75

Abstract

The stability, structural geometry, and electronic structure of the La-doped Sr1.9375La0.0625TiO3.968 75 are investigated by first-principles calculations based on the density functional theory. The calculated results reveal that the oxygen vacancies have a tendency to distribute in the ab planes of the perovskite SrTiO3 layer. The structural stability of Sr1.9375La0.0625TiO3.968 75 is weakened by the simultaneous substitution of La for Sr and the introduction of oxygen vacancies. After electron doping, the lattice parameter a increases while the lattice parameter c decreases. The corner-shared TiO6 octahedra dominate the main electronic properties of Sr2TiO4 and the Sr1.9375La0.0625TiO3.968 75 system shows n-type degenerate semiconductor features. There is an incipient localization of some of the doped electrons being trapped in the oxygen vacancy. The introduction of oxygen vacancy in Sr2TiO4 makes little contribution to the electrical activity of Sr1.9375La0.0625TiO3.968 75.