Materials Data on Hf4Si7Ni4 by Materials Project

Abstract

Hf4Ni4Si7 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to seven Si+2.86- atoms to form HfSi7 pentagonal bipyramids that share corners with eight equivalent NiSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, edges with three equivalent HfSi7 pentagonal bipyramids, faces with four equivalent NiSi6 octahedra, and faces with six HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 42–52°. There are a spread of Hf–Si bond distances ranging from 2.70–2.87 Å. In the second Hf4+ site, Hf4+ is bonded to seven Si+2.86- atoms to form HfSi7 pentagonal bipyramids that share corners with eight equivalent NiSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, an edgeedge with one HfSi7 pentagonal bipyramid, faces with four equivalent NiSi6 octahedra, and faces with six HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–52°. There are a spread of Hf–Si bond distances ranging from 2.69–2.87 Å. Ni1+ is bonded to six Si+2.86- atoms to form distorted NiSi6 octahedra that share corners with six equivalent NiSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, edges with three equivalent NiSi6 octahedra, faces with two equivalent NiSi6 octahedra, and faces with four HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 35–37°. There are four shorter (2.39 Å) and two longer (2.40 Å) Ni–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 6-coordinate geometry to one Hf4+, four equivalent Ni1+, and one Si+2.86- atom. The Si–Si bond length is 2.35 Å. In the second Si+2.86- site, Si+2.86- is bonded in a 10-coordinate geometry to eight Hf4+ and two equivalent Si+2.86- atoms. There are one shorter (2.55 Å) and one longer (2.56 Å) Si–Si bond lengths. In the third Si+2.86- site, Si+2.86- is bonded in a 9-coordinate geometry to five Hf4+ and four equivalent Ni1+ atoms. In the fourth Si+2.86- site, Si+2.86- is bonded in a 2-coordinate geometry to four Hf4+ and four equivalent Ni1+ atoms.