Materials Data on Ba3SrTa2O9 by Materials Project

Abstract

Ba3SrTa2O9 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to nine O2- atoms to form distorted BaO9 cuboctahedra that share corners with nine equivalent BaO9 cuboctahedra, edges with three equivalent SrO6 octahedra, faces with three equivalent BaO12 cuboctahedra, and faces with four equivalent TaO6 octahedra. There are three shorter (2.92 Å) and six longer (3.01 Å) Ba–O bond lengths. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, faces with six equivalent BaO9 cuboctahedra, faces with two equivalent SrO6 octahedra, and faces with six equivalent TaO6 octahedra. There are six shorter (2.95 Å) and six longer (3.01 Å) Ba–O bond lengths. Sr2+ is bonded to six equivalent O2- atoms to form SrO6 octahedra that share corners with six equivalent TaO6 octahedra, edges with six equivalent BaO9 cuboctahedra, and faces with two equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 7°. All Sr–O bond lengths are 2.41 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three equivalent SrO6 octahedra, corners with three equivalent TaO6 octahedra, and faces with seven BaO9 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–7°. There are three shorter (1.92 Å) and three longer (2.15 Å) Ta–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to three Ba2+, one Sr2+, and one Ta5+ atom.