DOI: 10.17188/1708398
title: Materials Data on Ca2SiO5 by Materials Project

description: Ca2SiO5 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Ca sites. In the first Ca site, Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with three CaO6 octahedra, corners with two equivalent SiO5 trigonal bipyramids, edges with two equivalent CaO6 octahedra, and edges with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 29–56°. There are a spread of Ca–O bond distances ranging from 2.34–2.41 Å. In the second Ca site, Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent CaO6 octahedra, corners with two equivalent SiO4 tetrahedra, edges with four CaO6 octahedra, edges with two equivalent CaO7 pentagonal bipyramids, and an edgeedge with one SiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 62–63°. There are a spread of Ca–O bond distances ranging from 2.33–2.52 Å. In the third Ca site, Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.39 Å. In the fourth Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one CaO7 pentagonal bipyramid, corners with two equivalent SiO4 tetrahedra, corners with two equivalent SiO5 trigonal bipyramids, edges with four CaO6 octahedra, and edges with two equivalent CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.33–2.59 Å. In the fifth Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with two equivalent CaO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, a cornercorner with one SiO5 trigonal bipyramid, edges with two equivalent CaO6 octahedra, and edges with two equivalent CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.28–2.40 Å. In the sixth Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with two equivalent CaO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, corners with three SiO5 trigonal bipyramids, edges with four CaO6 octahedra, and edges with two equivalent CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.28–2.42 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded to five O atoms to form distorted SiO5 trigonal bipyramids that share corners with four CaO6 octahedra, corners with two equivalent SiO5 trigonal bipyramids, an edgeedge with one CaO7 pentagonal bipyramid, and edges with two equivalent SiO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 51–64°. There are a spread of Si–O bond distances ranging from 1.65–1.81 Å. In the second Si site, Si is bonded to five O atoms to form distorted SiO5 trigonal bipyramids that share corners with two CaO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, corners with two equivalent SiO5 trigonal bipyramids, and edges with two equivalent SiO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 61–70°. There are a spread of Si–O bond distances ranging from 1.64–1.82 Å. In the third Si site, Si is bonded to four O atoms to form distorted SiO4 tetrahedra that share corners with four CaO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–69°. There are a spread of Si–O bond distances ranging from 1.62–2.13 Å. There are fifteen inequivalent O sites. In the first O site, O is bonded to three Ca and one Si atom to form distorted corner-sharing OCa3Si tetrahedra. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to three Ca and one Si atom. In the third O site, O is bonded in a rectangular see-saw-like geometry to four Ca atoms. In the fourth O site, O is bonded to four Ca atoms to form distorted OCa4 trigonal pyramids that share corners with two equivalent OCa3Si tetrahedra, corners with two equivalent OCa4 trigonal pyramids, and an edgeedge with one OCa3Si tetrahedra. In the fifth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Ca and one Si atom. In the sixth O site, O is bonded in a rectangular see-saw-like geometry to three Ca and one Si atom. In the seventh O site, O is bonded in a distorted trigonal planar geometry to three Ca atoms. In the eighth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Ca atoms. In the ninth O site, O is bonded in a trigonal planar geometry to three Ca atoms. In the tenth O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the eleventh O site, O is bonded in a trigonal planar geometry to three Ca atoms. In the twelfth O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with two equivalent OCa3Si tetrahedra, corners with two equivalent OCa4 trigonal pyramids, and an edgeedge with one OCa4 trigonal pyramid. In the thirteenth O site, O is bonded in a distorted T-shaped geometry to three Si atoms. In the fourteenth O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent Si atoms. In the fifteenth O site, O is bonded in a distorted T-shaped geometry to three Si atoms.