Materials Data on MgSi2 by Materials Project

Abstract

MgSi2 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to four Si atoms to form MgSi4 tetrahedra that share corners with two equivalent SiMg2Si3 square pyramids, corners with two equivalent MgSi4 tetrahedra, corners with six equivalent SiMgSi4 tetrahedra, an edgeedge with one SiMg2Si3 square pyramid, and an edgeedge with one MgSi4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.68–2.74 Å. In the second Mg site, Mg is bonded in a 8-coordinate geometry to six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.85–3.17 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 6-coordinate geometry to four Mg and two equivalent Si atoms. Both Si–Si bond lengths are 2.35 Å. In the second Si site, Si is bonded to one Mg and four Si atoms to form distorted SiMgSi4 tetrahedra that share corners with four equivalent SiMg2Si3 square pyramids, corners with two equivalent SiMgSi4 tetrahedra, and corners with six equivalent MgSi4 tetrahedra. There are one shorter (2.39 Å) and one longer (2.43 Å) Si–Si bond lengths. In the third Si site, Si is bonded to two equivalent Mg and three Si atoms to form distorted SiMg2Si3 square pyramids that share corners with two equivalent MgSi4 tetrahedra, corners with four equivalent SiMgSi4 tetrahedra, edges with two equivalent SiMg2Si3 square pyramids, and an edgeedge with one MgSi4 tetrahedra. There are two shorter (2.37 Å) and one longer (2.40 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded in a 6-coordinate geometry to three Mg and three Si atoms.