Materials Data on Ti4Co4Si7 by Materials Project

Abstract

Ti4Co4Si7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to seven Si+2.86- atoms to form TiSi7 pentagonal bipyramids that share corners with eight equivalent CoSi6 octahedra, corners with eight TiSi7 pentagonal bipyramids, edges with three equivalent TiSi7 pentagonal bipyramids, faces with four equivalent CoSi6 octahedra, and faces with six TiSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 42–51°. There are a spread of Ti–Si bond distances ranging from 2.61–2.80 Å. In the second Ti4+ site, Ti4+ is bonded to seven Si+2.86- atoms to form TiSi7 pentagonal bipyramids that share corners with eight equivalent CoSi6 octahedra, corners with eight TiSi7 pentagonal bipyramids, an edgeedge with one TiSi7 pentagonal bipyramid, faces with four equivalent CoSi6 octahedra, and faces with six TiSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 40–53°. There are a spread of Ti–Si bond distances ranging from 2.58–2.77 Å. Co1+ is bonded to six Si+2.86- atoms to form distorted CoSi6 octahedra that share corners with six equivalent CoSi6 octahedra, corners with eight TiSi7 pentagonal bipyramids, edges with three equivalent CoSi6 octahedra, faces with two equivalent CoSi6 octahedra, and faces with four TiSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 34–39°. There are two shorter (2.29 Å) and four longer (2.34 Å) Co–Si bond lengths. There are four inequivalent Si+2.86- sites. In the first Si+2.86- site, Si+2.86- is bonded in a 9-coordinate geometry to five Ti4+ and four equivalent Co1+ atoms. In the second Si+2.86- site, Si+2.86- is bonded in a 12-coordinate geometry to four Ti4+ and four equivalent Co1+ atoms. In the third Si+2.86- site, Si+2.86- is bonded in a 6-coordinate geometry to one Ti4+, four equivalent Co1+, and one Si+2.86- atom. The Si–Si bond length is 2.37 Å. In the fourth Si+2.86- site, Si+2.86- is bonded in a 10-coordinate geometry to eight Ti4+ and two equivalent Si+2.86- atoms. Both Si–Si bond lengths are 2.46 Å.