DOI: 10.17188/1262760
title: Materials Data on Na4TiSe4 by Materials Project

description: Na4TiSe4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are eight inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with four NaSe6 octahedra, corners with four TiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, an edgeedge with one NaSe6 octahedra, an edgeedge with one TiSe4 tetrahedra, an edgeedge with one NaSe5 trigonal bipyramid, and faces with two equivalent NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 40–57°. There are a spread of Na–Se bond distances ranging from 2.90–3.48 Å. In the second Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with four NaSe6 octahedra, corners with four TiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, an edgeedge with one NaSe6 octahedra, an edgeedge with one TiSe4 tetrahedra, an edgeedge with one NaSe5 trigonal bipyramid, and faces with two equivalent NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 31–54°. There are a spread of Na–Se bond distances ranging from 2.98–3.43 Å. In the third Na1+ site, Na1+ is bonded to six Se2- atoms to form distorted NaSe6 octahedra that share corners with four NaSe6 octahedra, corners with two equivalent TiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, an edgeedge with one NaSe6 octahedra, edges with two equivalent TiSe4 tetrahedra, and edges with three NaSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 31–48°. There are a spread of Na–Se bond distances ranging from 2.93–3.24 Å. In the fourth Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.89–3.39 Å. In the fifth Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.96–3.13 Å. In the sixth Na1+ site, Na1+ is bonded to five Se2- atoms to form distorted NaSe5 trigonal bipyramids that share corners with four NaSe6 octahedra, a cornercorner with one TiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, edges with two NaSe6 octahedra, edges with two equivalent TiSe4 tetrahedra, and edges with three NaSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Na–Se bond distances ranging from 2.97–3.14 Å. In the seventh Na1+ site, Na1+ is bonded to five Se2- atoms to form NaSe5 trigonal bipyramids that share corners with two equivalent NaSe6 octahedra, corners with three TiSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, edges with three NaSe6 octahedra, an edgeedge with one TiSe4 tetrahedra, and edges with three NaSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 25–73°. There are a spread of Na–Se bond distances ranging from 2.88–3.18 Å. In the eighth Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four Se2- atoms. There are a spread of Na–Se bond distances ranging from 3.00–3.08 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to four Se2- atoms to form TiSe4 tetrahedra that share corners with six NaSe6 octahedra, corners with two equivalent NaSe5 trigonal bipyramids, and edges with three NaSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 29–62°. There are a spread of Ti–Se bond distances ranging from 2.39–2.43 Å. In the second Ti4+ site, Ti4+ is bonded to four Se2- atoms to form TiSe4 tetrahedra that share corners with four NaSe6 octahedra, corners with two NaSe5 trigonal bipyramids, and edges with four NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 38–68°. There are a spread of Ti–Se bond distances ranging from 2.38–2.44 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to six Na1+ and one Ti4+ atom. In the second Se2- site, Se2- is bonded in a 7-coordinate geometry to six Na1+ and one Ti4+ atom. In the third Se2- site, Se2- is bonded in a distorted pentagonal bipyramidal geometry to six Na1+ and one Ti4+ atom. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Na1+ and one Ti4+ atom. In the fifth Se2- site, Se2- is bonded in a 7-coordinate geometry to six Na1+ and one Ti4+ atom. In the sixth Se2- site, Se2- is bonded in a 6-coordinate geometry to five Na1+ and one Ti4+ atom. In the seventh Se2- site, Se2- is bonded in a 6-coordinate geometry to five Na1+ and one Ti4+ atom. In the eighth Se2- site, Se2- is bonded in a 1-coordinate geometry to four Na1+ and one Ti4+ atom.