DOI: 10.17188/1732801
title: Materials Data on Ca9(Si3O16)2 by Materials Project

description: Ca9(Si3O16)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent Ca sites. In the first Ca site, Ca is bonded to six O atoms to form distorted CaO6 octahedra that share a cornercorner with one CaO6 octahedra, corners with four SiO4 tetrahedra, and an edgeedge with one CaO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ca–O bond distances ranging from 2.27–2.60 Å. In the second 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 2.23–2.68 Å. In the third Ca site, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.26–2.74 Å. In the fourth Ca site, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.22–2.63 Å. In the fifth Ca site, Ca is bonded to six O atoms to form distorted CaO6 octahedra that share corners with two equivalent CaO6 octahedra and corners with two equivalent OCa3O tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ca–O bond distances ranging from 2.16–2.70 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 64°. There are a spread of Si–O bond distances ranging from 1.59–1.77 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent CaO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 65–68°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 67°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are sixteen inequivalent O sites. In the first O site, O is bonded in a distorted trigonal non-coplanar geometry to two Ca and one Si atom. In the second O site, O is bonded to three Ca and one O atom to form distorted OCa3O tetrahedra that share a cornercorner with one CaO6 octahedra, corners with two equivalent OCa3Si tetrahedra, and corners with three equivalent OCa3Si trigonal pyramids. The corner-sharing octahedral tilt angles are 41°. The O–O bond length is 1.31 Å. In the third O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the fourth O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the fifth O site, O is bonded in a bent 120 degrees geometry to two Si atoms. In the sixth O site, O is bonded in a distorted bent 120 degrees geometry to two Si atoms. In the seventh O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and two Si atoms. In the eighth O site, O is bonded in a distorted bent 120 degrees geometry to one Si and one O atom. The O–O bond length is 1.35 Å. In the ninth O site, O is bonded to three Ca and one Si atom to form a mixture of distorted edge and corner-sharing OCa3Si trigonal pyramids. In the tenth O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with two equivalent OCa3O tetrahedra, a cornercorner with one OCa3Si trigonal pyramid, and an edgeedge with one OCa3Si tetrahedra. 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 in a trigonal planar geometry to three Ca atoms. In the thirteenth O site, O is bonded in a water-like geometry to one Ca and one O atom. In the fourteenth O site, O is bonded in an L-shaped geometry to one Ca and one O atom. The O–O bond length is 1.26 Å. In the fifteenth O site, O is bonded in a 3-coordinate geometry to two Ca and one O atom. In the sixteenth O site, O is bonded in a 2-coordinate geometry to one Ca and one O atom.