Materials Data on Na2Ti(SiO4)2 by Materials Project

Abstract

Na2Ti(SiO4)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Na sites. In the first Na site, Na is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Na–O bond distances ranging from 2.34–2.70 Å. In the second Na site, Na is bonded to six O atoms to form distorted NaO6 octahedra that share corners with two equivalent SiO4 tetrahedra, corners with two equivalent NaO4 trigonal pyramids, edges with two equivalent NaO6 octahedra, and an edgeedge with one NaO4 trigonal pyramid. There are a spread of Na–O bond distances ranging from 2.31–2.59 Å. In the third Na site, Na is bonded to four equivalent O atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent NaO6 octahedra, corners with four equivalent SiO4 tetrahedra, an edgeedge with one NaO6 octahedra, and edges with two equivalent NaO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 79°. There are two shorter (2.22 Å) and two longer (2.35 Å) Na–O bond lengths. Ti is bonded to six O atoms to form TiO6 octahedra that share corners with four SiO4 tetrahedra and edges with two equivalent TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.85–2.16 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 corners with three equivalent TiO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 30–56°. 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 NaO6 octahedra, a cornercorner with one TiO6 octahedra, corners with two equivalent SiO4 tetrahedra, and corners with two equivalent NaO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 30–50°. There are a spread of Si–O bond distances ranging from 1.59–1.68 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a distorted rectangular see-saw-like geometry to one Na, two equivalent Ti, and one Si atom. In the second O site, O is bonded in a water-like geometry to two equivalent Na atoms. In the third O site, O is bonded in a 3-coordinate geometry to one Na and two equivalent Si atoms. In the fourth O site, O is bonded in a distorted T-shaped geometry to one Na, one Ti, and one Si atom. In the fifth O site, O is bonded in a 2-coordinate geometry to two equivalent Na and two equivalent Si atoms. In the sixth O site, O is bonded in a 3-coordinate geometry to one Na, one Ti, and one Si atom. In the seventh O site, O is bonded in a 4-coordinate geometry to three Na and one Si atom. In the eighth O site, O is bonded in a trigonal non-coplanar geometry to one Na and two equivalent Ti atoms.