Materials Data on Ti4Si7Ni4 by Materials Project

Abstract

Ti4Ni4Si7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ti3+ sites. In the first Ti3+ site, Ti3+ is bonded to seven Si+2.86- atoms to form TiSi7 pentagonal bipyramids that share corners with eight equivalent NiSi6 octahedra, corners with eight TiSi7 pentagonal bipyramids, an edgeedge with one TiSi7 pentagonal bipyramid, faces with four equivalent NiSi6 octahedra, and faces with six TiSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 40–52°. There are a spread of Ti–Si bond distances ranging from 2.57–2.77 Å. In the second Ti3+ site, Ti3+ is bonded to seven Si+2.86- atoms to form distorted TiSi7 pentagonal bipyramids that share corners with eight equivalent NiSi6 octahedra, corners with eight TiSi7 pentagonal bipyramids, edges with three equivalent TiSi7 pentagonal bipyramids, faces with four equivalent NiSi6 octahedra, and faces with six TiSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 40–51°. There are a spread of Ti–Si bond distances ranging from 2.57–2.87 Å. Ni2+ is bonded to six Si+2.86- atoms to form distorted NiSi6 octahedra that share corners with six equivalent NiSi6 octahedra, corners with eight TiSi7 pentagonal bipyramids, edges with three equivalent NiSi6 octahedra, faces with two equivalent NiSi6 octahedra, and faces with four TiSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 35–41°. There are a spread of Ni–Si bond distances ranging from 2.33–2.38 Å. There are four inequivalent Si+2.86- sites. In the first Si+2.86- site, Si+2.86- is bonded in a 10-coordinate geometry to eight Ti3+ and two equivalent Si+2.86- atoms. There are one shorter (2.47 Å) and one longer (2.49 Å) Si–Si bond lengths. In the second Si+2.86- site, Si+2.86- is bonded in a 2-coordinate geometry to four Ti3+ and four equivalent Ni2+ atoms. In the third Si+2.86- site, Si+2.86- is bonded in a 9-coordinate geometry to five Ti3+ and four equivalent Ni2+ atoms. In the fourth Si+2.86- site, Si+2.86- is bonded in a 6-coordinate geometry to one Ti3+, four equivalent Ni2+, and one Si+2.86- atom. The Si–Si bond length is 2.35 Å.