Materials Data on Hf4Co4Si7 by Materials Project

Abstract

Hf4Co4Si7 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 CoSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, edges with three equivalent HfSi7 pentagonal bipyramids, faces with four equivalent CoSi6 octahedra, and faces with six HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 44–52°. There are a spread of Hf–Si bond distances ranging from 2.75–2.85 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 CoSi6 octahedra, corners with eight HfSi7 pentagonal bipyramids, an edgeedge with one HfSi7 pentagonal bipyramid, faces with four equivalent CoSi6 octahedra, and faces with six HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–53°. There are a spread of Hf–Si bond distances ranging from 2.71–2.86 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 HfSi7 pentagonal bipyramids, edges with three equivalent CoSi6 octahedra, faces with two equivalent CoSi6 octahedra, and faces with four HfSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 32–36°. There are a spread of Co–Si bond distances ranging from 2.36–2.39 Å. 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 Hf4+ and four equivalent Co1+ atoms. In the second Si+2.86- site, Si+2.86- is bonded in a 6-coordinate geometry to one Hf4+, four equivalent Co1+, and one Si+2.86- atom. The Si–Si bond length is 2.36 Å. In the third 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 (2.52 Å) and one longer (2.53 Å) Si–Si bond lengths. In the fourth Si+2.86- site, Si+2.86- is bonded in a 12-coordinate geometry to four Hf4+ and four equivalent Co1+ atoms.