Materials Data on Mg9Si5 by Materials Project

Abstract

Mg9Si5 crystallizes in the trigonal R32 space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded to four Si atoms to form a mixture of distorted edge and corner-sharing MgSi4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.65–2.80 Å. In the second Mg site, Mg is bonded to four Si atoms to form a mixture of distorted edge and corner-sharing MgSi4 tetrahedra. There are two shorter (2.73 Å) and two longer (2.80 Å) Mg–Si bond lengths. In the third Mg site, Mg is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.82–2.99 Å. In the fourth Mg site, Mg is bonded to four Si atoms to form a mixture of distorted edge and corner-sharing MgSi4 tetrahedra. There are two shorter (2.72 Å) and two longer (2.76 Å) Mg–Si bond lengths. There are five inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to nine Mg atoms. In the second Si site, Si is bonded in a 9-coordinate geometry to nine Mg atoms. In the third Si site, Si is bonded in a 7-coordinate geometry to six Mg and one Si atom. The Si–Si bond length is 2.50 Å. In the fourth Si site, Si is bonded in a 7-coordinate geometry to six Mg and one Si atom. In the fifth Si site, Si is bonded in a 9-coordinate geometry to nine Mg atoms.