Materials Data on Hf2Si4Mo3 by Materials Project

Abstract

Hf2Mo3Si4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Hf4+ is bonded to seven Si4- atoms to form HfSi7 pentagonal bipyramids that share corners with four equivalent MoSi6 octahedra, corners with six equivalent HfSi7 pentagonal bipyramids, corners with five equivalent MoSi6 pentagonal pyramids, edges with two equivalent HfSi7 pentagonal bipyramids, edges with three equivalent MoSi6 pentagonal pyramids, faces with two equivalent MoSi6 octahedra, faces with three equivalent HfSi7 pentagonal bipyramids, and faces with three equivalent MoSi6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 46–51°. There are a spread of Hf–Si bond distances ranging from 2.72–2.88 Å. There are two inequivalent Mo+2.67+ sites. In the first Mo+2.67+ site, Mo+2.67+ is bonded to six Si4- atoms to form MoSi6 octahedra that share corners with four equivalent MoSi6 octahedra, corners with eight equivalent HfSi7 pentagonal bipyramids, corners with six equivalent MoSi6 pentagonal pyramids, faces with four equivalent HfSi7 pentagonal bipyramids, and faces with four equivalent MoSi6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 50°. There are a spread of Mo–Si bond distances ranging from 2.51–2.80 Å. In the second Mo+2.67+ site, Mo+2.67+ is bonded to six Si4- atoms to form distorted MoSi6 pentagonal pyramids that share corners with three equivalent MoSi6 octahedra, corners with five equivalent HfSi7 pentagonal bipyramids, corners with four equivalent MoSi6 pentagonal pyramids, edges with three equivalent HfSi7 pentagonal bipyramids, edges with three equivalent MoSi6 pentagonal pyramids, faces with two equivalent MoSi6 octahedra, faces with three equivalent HfSi7 pentagonal bipyramids, and a faceface with one MoSi6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 40–42°. There are a spread of Mo–Si bond distances ranging from 2.48–2.61 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to two equivalent Hf4+, six Mo+2.67+, and one Si4- atom. The Si–Si bond length is 2.49 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Hf4+, four Mo+2.67+, and one Si4- atom. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Hf4+, four Mo+2.67+, and one Si4- atom. The Si–Si bond length is 2.52 Å.