DOI: 10.17188/1732949
title: Materials Data on Ca8Si4(O5F)3 by Materials Project

description: Ca8Si4(O5F)3 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are eight inequivalent Ca sites. In the first Ca site, Ca is bonded to seven O atoms to form distorted CaO7 hexagonal pyramids that share corners with three SiO4 tetrahedra, edges with two equivalent CaO5F octahedra, and edges with two SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.36–2.65 Å. In the second Ca site, Ca is bonded in a 7-coordinate geometry to six O and one F atom. There are a spread of Ca–O bond distances ranging from 2.37–2.67 Å. The Ca–F bond length is 2.31 Å. In the third Ca site, Ca is bonded to five O and one F atom to form CaO5F octahedra that share corners with five SiO4 tetrahedra and edges with two equivalent CaO7 hexagonal pyramids. There are a spread of Ca–O bond distances ranging from 2.31–2.43 Å. The Ca–F bond length is 2.40 Å. In the fourth Ca site, Ca is bonded to five O and one F atom to form CaO5F octahedra that share corners with five SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.33–2.44 Å. The Ca–F bond length is 2.37 Å. In the fifth Ca site, Ca is bonded in a 8-coordinate geometry to six O and two F atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.91 Å. There are one shorter (2.38 Å) and one longer (2.41 Å) Ca–F bond lengths. In the sixth Ca site, Ca is bonded in a 8-coordinate geometry to six O and two F atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.89 Å. There are one shorter (2.34 Å) and one longer (2.38 Å) Ca–F bond lengths. In the seventh Ca site, Ca is bonded in a 6-coordinate geometry to four O and three F atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.84 Å. There are a spread of Ca–F bond distances ranging from 2.35–2.42 Å. In the eighth Ca site, Ca is bonded in a 6-coordinate geometry to five O and two F atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.89 Å. There are one shorter (2.35 Å) and one longer (2.41 Å) Ca–F bond lengths. There are four 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 CaO7 hexagonal pyramid, corners with two CaO5F octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 33–48°. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO7 hexagonal pyramid, corners with two CaO5F octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–46°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three CaO5F octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 42–62°. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO7 hexagonal pyramid, corners with three CaO5F octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–63°. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. There are fifteen inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to two Ca and two Si atoms. In the second O site, O is bonded in a distorted bent 150 degrees geometry to two Ca and two Si atoms. 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 4-coordinate geometry to three Ca and one Si atom. In the sixth O site, O is bonded in a 1-coordinate geometry to three Ca and one Si atom. In the seventh O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si trigonal pyramids that share a cornercorner with one OCa4 tetrahedra, corners with four FCa4 tetrahedra, and an edgeedge with one FCa4 tetrahedra. In the eighth O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si trigonal pyramids that share corners with three OCa3Si tetrahedra, corners with three FCa4 tetrahedra, an edgeedge with one OCa3Si tetrahedra, and an edgeedge with one FCa4 tetrahedra. In the ninth O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. 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 4-coordinate geometry to three Ca and one Si atom. In the twelfth O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share a cornercorner with one OCa4 tetrahedra, corners with four FCa4 tetrahedra, a cornercorner with one OCa3Si trigonal pyramid, and an edgeedge with one OCa3Si trigonal pyramid. In the thirteenth O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the fourteenth O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the fifteenth O site, O is bonded to four Ca atoms to form OCa4 tetrahedra that share a cornercorner with one OCa3Si tetrahedra, corners with two equivalent FCa4 tetrahedra, corners with three OCa3Si trigonal pyramids, and edges with two FCa4 tetrahedra. There are three inequivalent F sites. In the first F site, F is bonded to four Ca atoms to form FCa4 tetrahedra that share corners with three OCa3Si tetrahedra, corners with two equivalent OCa3Si trigonal pyramids, edges with two FCa4 tetrahedra, and an edgeedge with one OCa3Si trigonal pyramid. In the second F site, F is bonded to four Ca atoms to form FCa4 tetrahedra that share a cornercorner with one OCa3Si tetrahedra, corners with two equivalent FCa4 tetrahedra, corners with two equivalent OCa3Si trigonal pyramids, an edgeedge with one OCa4 tetrahedra, an edgeedge with one FCa4 tetrahedra, and an edgeedge with one OCa3Si trigonal pyramid. In the third F site, F is bonded to four Ca atoms to form FCa4 tetrahedra that share corners with two equivalent OCa3Si tetrahedra, corners with two equivalent FCa4 tetrahedra, corners with three OCa3Si trigonal pyramids, an edgeedge with one OCa4 tetrahedra, and an edgeedge with one FCa4 tetrahedra.