DOI: 10.17188/1713472
title: Materials Data on Na2Ca5TiSi4(O8F)2 by Materials Project

description: Na2Ca5TiSi4(O8F)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to four O and two F atoms to form NaO4F2 octahedra that share corners with two SiO4 tetrahedra, edges with two equivalent CaO6F2 hexagonal bipyramids, edges with two equivalent NaO4F2 octahedra, and edges with two equivalent TiO6 octahedra. There are a spread of Na–O bond distances ranging from 2.40–2.49 Å. There are one shorter (2.42 Å) and one longer (2.43 Å) Na–F bond lengths. In the second Na site, Na is bonded to four O and two F atoms to form distorted NaO4F2 octahedra that share corners with two SiO4 tetrahedra, edges with two equivalent CaO6F2 hexagonal bipyramids, edges with two equivalent NaO4F2 octahedra, and edges with two equivalent TiO6 octahedra. There are a spread of Na–O bond distances ranging from 2.36–2.76 Å. There are one shorter (2.36 Å) and one longer (2.43 Å) Na–F bond lengths. There are five inequivalent Ca sites. In the first 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 2.33–2.88 Å. In the second Ca site, Ca is bonded in a 7-coordinate geometry to seven O and one F atom. There are a spread of Ca–O bond distances ranging from 2.41–2.98 Å. The Ca–F bond length is 2.41 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 2.36–2.80 Å. In the fourth Ca site, Ca is bonded to six O and two F atoms to form distorted CaO6F2 hexagonal bipyramids that share edges with two equivalent TiO6 octahedra, edges with four NaO4F2 octahedra, and edges with four SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.37–2.68 Å. There are one shorter (2.25 Å) and one longer (2.26 Å) Ca–F bond lengths. In the fifth 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 2.39–2.67 Å. The Ca–F bond length is 2.42 Å. Ti is bonded to six O atoms to form distorted TiO6 octahedra that share corners with four SiO4 tetrahedra, edges with two equivalent CaO6F2 hexagonal bipyramids, and edges with four NaO4F2 octahedra. There are a spread of Ti–O bond distances ranging from 1.75–2.20 Å. 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 NaO4F2 octahedra, a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 42–72°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one NaO4F2 octahedra, a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 42–72°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one NaO4F2 octahedra, a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 31–69°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one NaO4F2 octahedra, a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 26–72°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. There are sixteen inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to one Ca and two Si atoms. In the second O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share a cornercorner with one FNa2Ca2 tetrahedra and corners with eight ONa2CaTi tetrahedra. In the third O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with two equivalent FNa2Ca2 tetrahedra and corners with seven ONa2CaTi tetrahedra. In the fourth O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, one Ti, and one Si atom. In the fifth O site, O is bonded in a rectangular see-saw-like geometry to two Na, one Ca, and one Ti atom. In the sixth O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, one Ti, and one Si atom. In the seventh O site, O is bonded in a 1-coordinate geometry to three Ca and one Si atom. In the eighth O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, one Ti, and one Si atom. In the ninth O site, O is bonded to two Na, one Ca, and one Ti atom to form distorted ONa2CaTi tetrahedra that share corners with two equivalent FNa2Ca2 tetrahedra, corners with three OCa3Si tetrahedra, and corners with two equivalent FNa2Ca2 trigonal pyramids. In the tenth O site, O is bonded in a 2-coordinate geometry to two Ca and two Si atoms. In the eleventh O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with six OCa3Si tetrahedra and corners with two equivalent FNa2Ca2 trigonal pyramids. In the twelfth O site, O is bonded in a 1-coordinate geometry to three Ca and one Si atom. In the thirteenth O site, O is bonded in a distorted rectangular see-saw-like geometry to one Na, one Ca, one Ti, 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 three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with six OCa3Si tetrahedra and a cornercorner with one FNa2Ca2 trigonal pyramid. In the sixteenth O site, O is bonded in a 1-coordinate geometry to three Ca and one Si atom. There are two inequivalent F sites. In the first F site, F is bonded to two Na and two Ca atoms to form distorted FNa2Ca2 trigonal pyramids that share a cornercorner with one FNa2Ca2 tetrahedra, corners with five ONa2CaTi tetrahedra, and an edgeedge with one FNa2Ca2 tetrahedra. In the second F site, F is bonded to two Na and two Ca atoms to form distorted FNa2Ca2 tetrahedra that share corners with five ONa2CaTi tetrahedra, a cornercorner with one FNa2Ca2 trigonal pyramid, and an edgeedge with one FNa2Ca2 trigonal pyramid.