Materials Data on Mg3Si4 by Materials Project

Abstract

Mg3Si4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Mg sites. In the first Mg site, Mg is bonded to one Mg and six Si atoms to form distorted MgMgSi6 octahedra that share corners with three equivalent SiMg4Si3 pentagonal bipyramids. The Mg–Mg bond length is 3.25 Å. There are a spread of Mg–Si bond distances ranging from 2.81–2.96 Å. In the second Mg site, Mg is bonded in a 3-coordinate geometry to three Mg and seven Si atoms. There are one shorter (3.22 Å) and one longer (3.26 Å) Mg–Mg bond lengths. There are a spread of Mg–Si bond distances ranging from 2.78–3.19 Å. In the third Mg site, Mg is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.69–3.01 Å. In the fourth Mg site, Mg is bonded in a 4-coordinate geometry to one Mg and six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.67–3.09 Å. In the fifth Mg site, Mg is bonded in a 5-coordinate geometry to seven Si atoms. There are a spread of Mg–Si bond distances ranging from 2.71–3.12 Å. In the sixth Mg site, Mg is bonded in a 5-coordinate geometry to one Mg and six Si atoms. There are a spread of Mg–Si bond distances ranging from 2.66–3.15 Å. There are eight inequivalent Si sites. In the first Si site, Si is bonded to four Mg and three Si atoms to form distorted SiMg4Si3 pentagonal bipyramids that share corners with three equivalent MgMgSi6 octahedra. The corner-sharing octahedra tilt angles range from 37–123°. There are a spread of Si–Si bond distances ranging from 2.38–2.43 Å. In the second Si site, Si is bonded in a 9-coordinate geometry to seven Mg and two Si atoms. There are one shorter (2.46 Å) and one longer (2.51 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 8-coordinate geometry to six Mg and two Si atoms. There are one shorter (2.42 Å) and one longer (2.43 Å) Si–Si bond lengths. In the fourth Si site, Si is bonded in a 7-coordinate geometry to four Mg and three Si atoms. The Si–Si bond length is 2.43 Å. In the fifth Si site, Si is bonded in a 7-coordinate geometry to four Mg and three Si atoms. The Si–Si bond length is 2.37 Å. In the sixth Si site, Si is bonded in a 7-coordinate geometry to three Mg and four Si atoms. The Si–Si bond length is 2.41 Å. In the seventh Si site, Si is bonded in a 7-coordinate geometry to six Mg and one Si atom. In the eighth Si site, Si is bonded in a 7-coordinate geometry to five Mg and two Si atoms.