Materials Data on Sr2CaTi3O9 by Materials Project

Abstract

Sr2CaTi3O9 crystallizes in the orthorhombic Fmm2 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 four equivalent SrO12 cuboctahedra, corners with eight equivalent CaO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight equivalent TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.64–2.95 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, a faceface with one SrO12 cuboctahedra, faces with five equivalent CaO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.64–2.93 Å. In the third 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. There are a spread of Sr–O bond distances ranging from 2.64–2.93 Å. Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent SrO12 cuboctahedra, corners with eight equivalent CaO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight TiO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.62–2.94 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra, faces with two equivalent CaO12 cuboctahedra, and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–13°. There is five shorter (1.97 Å) and one longer (1.98 Å) Ti–O bond length. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra, faces with four equivalent SrO12 cuboctahedra, and faces with four equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–13°. All Ti–O bond lengths are 1.97 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+, two equivalent Ca2+, and two equivalent Ti4+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to four Sr2+ and two equivalent Ti4+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+, two equivalent Ca2+, and two Ti4+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to three Sr2+, one Ca2+, and two equivalent Ti4+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to three Sr2+, one Ca2+, and two equivalent Ti4+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+, one Ca2+, and two equivalent Ti4+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sr2+, two equivalent Ca2+, and two equivalent Ti4+ atoms.