DOI: 10.17188/1747092
title: Materials Data on Na2Ca5TiSi4(O8F)2 by Materials Project

description: Na2Ca5TiSi4(O8F)2 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first 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 2.46–2.67 Å. There are one shorter (2.39 Å) and one longer (2.40 Å) Na–F bond lengths. In the second Na site, Na is bonded to six O and two F atoms to form distorted NaO6F2 hexagonal bipyramids that share a cornercorner with one CaO5F octahedra, edges with two equivalent CaO4F2 octahedra, edges with two equivalent TiO6 octahedra, and edges with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 61°. There are a spread of Na–O bond distances ranging from 2.38–2.79 Å. There are one shorter (2.28 Å) and one longer (2.29 Å) Na–F bond lengths. There are five inequivalent Ca sites. In the first Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one CaO4F2 octahedra, a cornercorner with one TiO6 octahedra, corners with five SiO4 tetrahedra, and edges with two CaO6 octahedra. The corner-sharing octahedra tilt angles range from 52–69°. There are a spread of Ca–O bond distances ranging from 2.33–2.41 Å. In the second Ca site, Ca is bonded to four O and two F atoms to form distorted CaO4F2 octahedra that share corners with three CaO6 octahedra, corners with two SiO4 tetrahedra, edges with two equivalent NaO6F2 hexagonal bipyramids, and edges with two equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–69°. There are a spread of Ca–O bond distances ranging from 2.35–2.52 Å. There are one shorter (2.29 Å) and one longer (2.30 Å) Ca–F bond lengths. In the third Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one CaO4F2 octahedra, a cornercorner with one TiO6 octahedra, corners with five SiO4 tetrahedra, and edges with three CaO6 octahedra. The corner-sharing octahedra tilt angles range from 47–63°. There are a spread of Ca–O bond distances ranging from 2.33–2.41 Å. In the fourth Ca site, Ca is bonded to five O and one F atom to form distorted CaO5F octahedra that share a cornercorner with one NaO6F2 hexagonal bipyramid, a cornercorner with one CaO4F2 octahedra, corners with five SiO4 tetrahedra, and edges with three CaO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ca–O bond distances ranging from 2.38–2.52 Å. The Ca–F bond length is 2.31 Å. In the fifth 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 2.36–2.54 Å. The Ca–F bond length is 2.31 Å. Ti is bonded to six O atoms to form TiO6 octahedra that share corners with two CaO6 octahedra, corners with four SiO4 tetrahedra, edges with two equivalent NaO6F2 hexagonal bipyramids, and edges with two equivalent CaO4F2 octahedra. The corner-sharing octahedra tilt angles range from 47–52°. There are a spread of Ti–O bond distances ranging from 1.80–2.13 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 TiO6 octahedra, corners with three CaO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 36–63°. There are a spread of Si–O bond distances ranging from 1.62–1.66 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, corners with five CaO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 28–73°. 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 TiO6 octahedra, corners with five CaO4F2 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 24–73°. 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, corners with four CaO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 39–73°. 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 4-coordinate geometry to three Ca and one Si atom. 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, corners with three ONaCa2Ti tetrahedra, a cornercorner with one ONaCa2Ti trigonal pyramid, and an edgeedge with one OCa3Si tetrahedra. In the third O site, O is bonded in a 3-coordinate geometry to two Ca and one Si atom. In the fourth O site, O is bonded in a distorted trigonal planar geometry to two Ca and one Si atom. In the fifth O site, O is bonded in a 2-coordinate geometry to one Na and two Si atoms. 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 distorted trigonal planar geometry to two 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 in a distorted trigonal planar geometry to two Ca and one Si atom. 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 FNa2Ca2 tetrahedra, a cornercorner with one ONaCa2Ti trigonal pyramid, and edges with two OCa3Si tetrahedra. In the eleventh O site, O is bonded to one Na, two Ca, and one Ti atom to form distorted ONaCa2Ti trigonal pyramids that share corners with three OCa3Si tetrahedra, corners with four FNa2Ca2 tetrahedra, and an edgeedge with one ONaCa2Ti tetrahedra. In the twelfth O site, O is bonded to one Na, two Ca, and one Ti atom to form distorted ONaCa2Ti tetrahedra that share corners with two OCa3Si tetrahedra, corners with four FNa2Ca2 tetrahedra, a cornercorner with one ONaCa2Ti trigonal pyramid, and an edgeedge with one ONaCa2Ti trigonal pyramid. In the thirteenth O site, O is bonded in a 4-coordinate geometry to two Na, one Ti, and one Si atom. In the fourteenth O site, O is bonded to three Ca and one Si atom to form distorted OCa3Si tetrahedra that share corners with two FNa2Ca2 tetrahedra, corners with three OCa3Si tetrahedra, and an edgeedge with one OCa3Si tetrahedra. In the fifteenth O site, O is bonded in a 4-coordinate geometry to two Na, one Ti, and one Si atom. In the sixteenth O site, O is bonded in a 2-coordinate geometry to one Na and two Si atoms. 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 tetrahedra that share a cornercorner with one FNa2Ca2 tetrahedra, corners with four OCa3Si tetrahedra, corners with two equivalent ONaCa2Ti trigonal pyramids, and an edgeedge with one FNa2Ca2 tetrahedra. In the second F site, F is bonded to two Na and two Ca atoms to form FNa2Ca2 tetrahedra that share a cornercorner with one FNa2Ca2 tetrahedra, corners with five OCa3Si tetrahedra, corners with two equivalent ONaCa2Ti trigonal pyramids, and an edgeedge with one FNa2Ca2 tetrahedra.