DOI: 10.17188/1656378
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 to six O and two F atoms to form distorted NaO6F2 hexagonal bipyramids that share edges with two equivalent TiO6 octahedra and edges with four SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.41–2.75 Å. There are one shorter (2.25 Å) and one longer (2.29 Å) Na–F bond lengths. In the second Na site, Na is bonded in a 6-coordinate geometry to five O and one F atom. There are a spread of Na–O bond distances ranging from 2.43–2.69 Å. The Na–F bond length is 2.46 Å. There are five inequivalent Ca sites. In the first Ca site, Ca is bonded in a 6-coordinate geometry to four O and two F atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.43 Å. There are one shorter (2.33 Å) and one longer (2.42 Å) Ca–F bond lengths. In the second Ca site, Ca is bonded in a 6-coordinate geometry to four O and two F atoms. There are a spread of Ca–O bond distances ranging from 2.38–2.41 Å. There are one shorter (2.34 Å) and one longer (2.41 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 TiO6 octahedra, corners with five SiO4 tetrahedra, and an edgeedge with one CaO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Ca–O bond distances ranging from 2.30–2.41 Å. In the fourth Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with five SiO4 tetrahedra, and an edgeedge with one CaO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Ca–O bond distances ranging from 2.34–2.43 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 2.35–2.58 Å. The Ca–F bond length is 2.35 Å. Ti is bonded to six O atoms to form TiO6 octahedra that share corners with two CaO6 octahedra, corners with four SiO4 tetrahedra, and edges with two equivalent NaO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 52–54°. There are a spread of Ti–O bond distances ranging from 1.88–2.04 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 two equivalent CaO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 35–52°. 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 two equivalent CaO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one NaO6F2 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 36–51°. 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 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 33–56°. There are a spread of Si–O bond distances ranging from 1.61–1.66 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 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 34–58°. There is two shorter (1.62 Å) and two longer (1.66 Å) Si–O bond length. There are sixteen inequivalent O sites. In the first O site, O is bonded to three Ca and one Ti atom to form distorted OCa3Ti tetrahedra that share a cornercorner with one OCa3Ti tetrahedra, corners with four FNa2Ca2 tetrahedra, a cornercorner with one ONaCa2Si trigonal pyramid, and an edgeedge with one OCa3Ti tetrahedra. In the second O site, O is bonded to three Ca and one Ti atom to form distorted OCa3Ti tetrahedra that share corners with two OCa3Ti tetrahedra, corners with four FNa2Ca2 tetrahedra, a cornercorner with one ONaCa2Si trigonal pyramid, and an edgeedge with one OCa3Ti tetrahedra. In the third O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, and one Si atom. In the fourth O site, O is bonded in a 3-coordinate geometry to two Ca and one Si atom. In the fifth O site, O is bonded in a distorted trigonal non-coplanar geometry to one Na, one Ca, and one Si atom. In the sixth O site, O is bonded in a distorted trigonal planar geometry to two Ca 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 2-coordinate geometry to one Na and two Si atoms. In the ninth 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 tenth O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, one Ti, and one Si atom. In the eleventh O site, O is bonded to one Na, two Ca, and one Si atom to form distorted ONaCa2Si trigonal pyramids that share a cornercorner with one FNa2Ca2 tetrahedra, corners with two OCa3Ti tetrahedra, and an edgeedge with one ONaCa2Si tetrahedra. 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 in a 4-coordinate 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 one Na, one Ca, one Ti, and one Si atom. In the fifteenth O site, O is bonded in a 4-coordinate geometry to one Na, two Ca, and one Si atom. In the sixteenth O site, O is bonded to one Na, two Ca, and one Si atom to form distorted ONaCa2Si tetrahedra that share a cornercorner with one OCa3Ti tetrahedra, corners with two FNa2Ca2 tetrahedra, and an edgeedge with one ONaCa2Si trigonal pyramid. There are two inequivalent F sites. In the first F site, F is bonded to two Na and two Ca atoms to form FNa2Ca2 tetrahedra that share a cornercorner with one FNaCa3 tetrahedra, corners with five OCa3Ti tetrahedra, a cornercorner with one ONaCa2Si trigonal pyramid, and an edgeedge with one FNaCa3 tetrahedra. In the second F site, F is bonded to one Na and three Ca atoms to form FNaCa3 tetrahedra that share a cornercorner with one FNa2Ca2 tetrahedra, corners with five OCa3Ti tetrahedra, and an edgeedge with one FNa2Ca2 tetrahedra.