Materials Data on MgSi2 by Materials Project

Abstract

MgSi2 is Tungsten Carbide-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six Si atoms to form MgSi6 octahedra that share corners with six SiMg3Si3 octahedra, edges with six MgSi6 octahedra, and edges with six SiMg3Si3 octahedra. The corner-sharing octahedral tilt angles are 17°. There are a spread of Mg–Si bond distances ranging from 2.87–2.89 Å. In the second Mg site, Mg is bonded to six Si atoms to form MgSi6 octahedra that share corners with six SiMg3Si3 octahedra, edges with six MgSi6 octahedra, and edges with six SiMg3Si3 octahedra. The corner-sharing octahedral tilt angles are 17°. There are four shorter (2.88 Å) and two longer (2.89 Å) Mg–Si bond lengths. In the third Mg site, Mg is bonded to six Si atoms to form MgSi6 octahedra that share corners with six SiMg3Si3 octahedra, edges with six MgSi6 octahedra, and edges with six SiMg3Si3 octahedra. The corner-sharing octahedra tilt angles range from 16–17°. There are a spread of Mg–Si bond distances ranging from 2.87–2.89 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded to three Mg and three Si atoms to form distorted SiMg3Si3 octahedra that share corners with three MgSi6 octahedra, corners with three SiMg3Si3 octahedra, edges with three MgSi6 octahedra, and edges with nine SiMg3Si3 octahedra. The corner-sharing octahedra tilt angles range from 0–17°. All Si–Si bond lengths are 2.37 Å. In the second Si site, Si is bonded to three Mg and three Si atoms to form distorted SiMg3Si3 octahedra that share corners with three equivalent MgSi6 octahedra, corners with three SiMg3Si3 octahedra, edges with three MgSi6 octahedra, and edges with nine SiMg3Si3 octahedra. The corner-sharing octahedra tilt angles range from 0–17°. Both Si–Si bond lengths are 2.37 Å. In the third Si site, Si is bonded to three Mg and three Si atoms to form distorted SiMg3Si3 octahedra that share corners with three MgSi6 octahedra, corners with three SiMg3Si3 octahedra, edges with three MgSi6 octahedra, and edges with nine SiMg3Si3 octahedra. The corner-sharing octahedra tilt angles range from 0–17°. There are one shorter (2.36 Å) and two longer (2.37 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded to three Mg and three Si atoms to form distorted SiMg3Si3 octahedra that share corners with three equivalent MgSi6 octahedra, corners with three SiMg3Si3 octahedra, edges with three MgSi6 octahedra, and edges with nine SiMg3Si3 octahedra. The corner-sharing octahedra tilt angles range from 0–17°.