Materials Data on Mg2Si by Materials Project

Abstract

Mg2Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five equivalent Si4- atoms to form MgSi5 trigonal bipyramids that share corners with twelve equivalent MgSi6 octahedra, corners with eight equivalent MgSi5 trigonal bipyramids, edges with six equivalent MgSi5 trigonal bipyramids, and faces with six equivalent MgSi6 octahedra. The corner-sharing octahedra tilt angles range from 30–60°. There are three shorter (2.67 Å) and two longer (3.04 Å) Mg–Si bond lengths. In the second Mg2+ site, Mg2+ is bonded to six equivalent Si4- atoms to form MgSi6 octahedra that share corners with twelve equivalent MgSi6 octahedra, corners with twelve equivalent MgSi5 trigonal bipyramids, edges with six equivalent MgSi6 octahedra, faces with two equivalent MgSi6 octahedra, and faces with six equivalent MgSi5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 52°. All Mg–Si bond lengths are 3.08 Å. Si4- is bonded in a 11-coordinate geometry to eleven Mg2+ atoms.