DOI: 10.17188/1202073
title: Materials Data on Ca3SiO5 by Materials Project

description: Ca3SiO5 crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with three equivalent CaO7 pentagonal bipyramids, corners with four SiO4 tetrahedra, edges with two equivalent CaO6 octahedra, and faces with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 74°. There are a spread of Ca–O bond distances ranging from 2.29–2.54 Å. In the second Ca2+ site, Ca2+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.58 Å. In the third Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with three equivalent CaO6 octahedra, corners with three SiO4 tetrahedra, edges with two equivalent CaO7 pentagonal bipyramids, an edgeedge with one SiO4 tetrahedra, faces with two equivalent CaO6 octahedra, and faces with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 18–38°. There are a spread of Ca–O bond distances ranging from 2.30–2.72 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six equivalent CaO6 octahedra and edges with three equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. There is one shorter (1.62 Å) and three longer (1.65 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with three equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. There is three shorter (1.65 Å) and one longer (1.68 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with six equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 63°. All Si–O bond lengths are 1.64 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ca2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to four Ca2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Ca2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded to six Ca2+ atoms to form face-sharing OCa6 octahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Ca2+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent Ca2+ and one Si4+ atom. In the eighth O2- site, O2- is bonded to six Ca2+ atoms to form a mixture of distorted corner and face-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles are 9°. In the ninth O2- site, O2- is bonded to six Ca2+ atoms to form a mixture of corner and face-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles are 9°.