DOI: 10.17188/1750934
title: Materials Data on Na2Ti2Si2O11 by Materials Project

description: Na2Ti2Si2O11 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Na2Ti2Si2O11 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Na sites. In the first Na site, Na is bonded to eight O atoms to form distorted NaO8 hexagonal bipyramids that share corners with two equivalent NaO8 hexagonal bipyramids, corners with two equivalent TiO6 octahedra, edges with four SiO4 tetrahedra, and edges with two equivalent TiO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Na–O bond distances ranging from 2.46–2.80 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.31–2.77 Å. There are two inequivalent Ti sites. In the first Ti site, Ti is bonded to five O atoms to form TiO5 trigonal bipyramids that share a cornercorner with one TiO6 octahedra, corners with four SiO4 tetrahedra, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 46°. There are a spread of Ti–O bond distances ranging from 1.80–1.95 Å. In the second Ti site, Ti is bonded to six O atoms to form TiO6 octahedra that share corners with two equivalent NaO8 hexagonal bipyramids, corners with three SiO4 tetrahedra, a cornercorner with one TiO5 trigonal bipyramid, and edges with two equivalent TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.82–2.23 Å. There are two 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, a cornercorner with one SiO4 tetrahedra, corners with two equivalent TiO5 trigonal bipyramids, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 51°. 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 corners with two equivalent TiO6 octahedra, a cornercorner with one SiO4 tetrahedra, corners with two equivalent TiO5 trigonal bipyramids, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are eleven inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Na, one Ti, and one Si atom. In the second O site, O is bonded in a 4-coordinate geometry to two equivalent Na and two Si atoms. In the third O site, O is bonded in a 4-coordinate geometry to one Na, two equivalent Ti, and one Si atom. In the fourth O site, O is bonded in a 4-coordinate geometry to two equivalent Na, one Ti, and one Si atom. In the fifth O site, O is bonded in a bent 120 degrees geometry to one Na and one O atom. The O–O bond length is 1.23 Å. In the sixth O site, O is bonded in a 4-coordinate geometry to two Na and two equivalent Ti atoms. In the seventh O site, O is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na and two Ti atoms. In the eighth O site, O is bonded in a distorted bent 150 degrees geometry to one Na, one Ti, and one Si atom. In the ninth O site, O is bonded in a 3-coordinate geometry to one Na, one Ti, and one Si atom. In the tenth O site, O is bonded in a single-bond geometry to one O atom. In the eleventh O site, O is bonded in a distorted trigonal non-coplanar geometry to one Na, one Ti, and one Si atom.