DOI: 10.17188/1716103
title: Materials Data on Na3Ca4TiSi4(O8F)2 by Materials Project

description: Na3Ca4TiSi4(O8F)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are three inequivalent Na sites. In the first Na site, Na is bonded to six O and two F atoms to form distorted NaO6F2 hexagonal bipyramids that share edges with two equivalent NaO4F2 octahedra, edges with two equivalent TiO6 octahedra, and edges with four SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.38–2.73 Å. There are one shorter (2.28 Å) and one longer (2.31 Å) Na–F bond lengths. In the second Na site, Na is bonded in a 6-coordinate geometry to four O and two F atoms. There are a spread of Na–O bond distances ranging from 2.38–2.95 Å. There are one shorter (2.31 Å) and one longer (2.34 Å) Na–F bond lengths. In the third 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 NaO6F2 hexagonal bipyramids, and edges with two equivalent TiO6 octahedra. There are a spread of Na–O bond distances ranging from 2.39–2.75 Å. There are one shorter (2.31 Å) and one longer (2.34 Å) Na–F bond lengths. There are four 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 2.35–2.68 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 2.41–2.75 Å. The Ca–F bond length is 2.29 Å. In the third Ca site, Ca is bonded in a 6-coordinate geometry to five O and one F atom. There are a spread of Ca–O bond distances ranging from 2.42–2.52 Å. The Ca–F bond length is 2.27 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 2.34–2.76 Å. Ti is bonded to six O atoms to form distorted TiO6 octahedra that share corners with four SiO4 tetrahedra, edges with two equivalent NaO6F2 hexagonal bipyramids, and edges with two equivalent NaO4F2 octahedra. There are a spread of Ti–O bond distances ranging from 1.74–2.19 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 NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 40–73°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedral tilt angles are 21°. 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 a cornercorner with one NaO4F2 octahedra, a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 17–79°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedral tilt angles are 42°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. There are sixteen inequivalent O sites. In the first O site, O is bonded in a 4-coordinate geometry to two Na, one Ti, and one Si atom. In the second O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. 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 two Na, one Ti, and one Si atom. In the fifth O site, O is bonded in a distorted 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 two Na, one Ti, and one Si atom. In the seventh O site, O is bonded in a 2-coordinate geometry to one Na and two Si atoms. In the eighth O site, O is bonded in a 4-coordinate geometry to two Na, one Ti, and one Si atom. In the ninth O site, O is bonded in a 1-coordinate geometry to two Ca and one Si atom. In the tenth O site, O is bonded to two Na, one Ca, and one Ti atom to form distorted ONa2CaTi tetrahedra that share corners with three OCa3Si tetrahedra and corners with two equivalent FNa3Ca trigonal pyramids. In the eleventh O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with seven ONa2CaTi tetrahedra and corners with two equivalent FNa3Ca trigonal pyramids. In the twelfth O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the thirteenth O site, O is bonded to three Ca and one Si atom to form distorted corner-sharing OCa3Si tetrahedra. In the fourteenth O site, O is bonded to three Ca and one Si atom to form distorted corner-sharing OCa3Si tetrahedra. In the fifteenth O site, O is bonded in a 2-coordinate geometry to one Na and two Si atoms. In the sixteenth O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with eight ONa2CaTi tetrahedra and a cornercorner with one FNa3Ca trigonal pyramid. There are two inequivalent F sites. In the first F site, F is bonded in a rectangular see-saw-like geometry to three Na and one Ca atom. In the second F site, F is bonded to three Na and one Ca atom to form distorted FNa3Ca trigonal pyramids that share corners with five ONa2CaTi tetrahedra.