DOI: 10.17188/1737926
title: Materials Data on SrCaTi2(GeO5)2 by Materials Project

description: SrCaTi2(GeO5)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.46–2.71 Å. Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with four GeO4 tetrahedra, edges with four TiO6 octahedra, and an edgeedge with one GeO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.33–2.59 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 two equivalent TiO6 octahedra, corners with four GeO4 tetrahedra, and edges with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 31–37°. There are a spread of Ti–O bond distances ranging from 1.80–2.05 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with four GeO4 tetrahedra, and edges with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 31–37°. There are a spread of Ti–O bond distances ranging from 1.80–2.05 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four TiO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, and an edgeedge with one CaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 39–56°. All Ge–O bond lengths are 1.78 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four TiO6 octahedra and corners with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 33–56°. There is one shorter (1.77 Å) and three longer (1.78 Å) Ge–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+, one Ti4+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ti4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded to one Sr2+, one Ca2+, one Ti4+, and one Ge4+ atom to form distorted corner-sharing OSrCaTiGe tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Sr2+, one Ca2+, one Ti4+, and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Ge4+ atom. In the eighth O2- site, O2- is bonded in a distorted T-shaped geometry to one Sr2+, one Ti4+, and one Ge4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Sr2+, one Ca2+, one Ti4+, and one Ge4+ atom. In the tenth O2- site, O2- is bonded to one Sr2+, one Ca2+, one Ti4+, and one Ge4+ atom to form distorted corner-sharing OSrCaTiGe tetrahedra.