Materials Data on Sr7CaTi8O24 by Materials Project

Abstract

Sr7CaTi8O24 is (Cubic) Perovskite-derived structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with two equivalent CaO12 cuboctahedra, faces with four equivalent SrO12 cuboctahedra, and faces with eight equivalent TiO6 octahedra. All Sr–O bond lengths are 2.78 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, corners with eight equivalent SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight equivalent TiO6 octahedra. There are eight shorter (2.78 Å) and four longer (2.80 Å) Sr–O bond lengths. In the third Sr2+ site, Sr2+ is bonded to twelve equivalent O2- atoms to form SrO12 cuboctahedra that share corners with twelve equivalent SrO12 cuboctahedra, faces with six equivalent SrO12 cuboctahedra, and faces with eight equivalent TiO6 octahedra. All Sr–O bond lengths are 2.79 Å. Ca2+ is bonded to twelve equivalent O2- atoms to form CaO12 cuboctahedra that share corners with twelve equivalent SrO12 cuboctahedra, faces with six equivalent SrO12 cuboctahedra, and faces with eight equivalent TiO6 octahedra. All Ca–O bond lengths are 2.76 Å. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent TiO6 octahedra, a faceface with one CaO12 cuboctahedra, and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. There is three shorter (1.96 Å) and three longer (1.97 Å) Ti–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to three Sr2+, one Ca2+, and two equivalent Ti4+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ti4+ atoms.