DOI: 10.17188/1729288
title: Materials Data on Mg6Si5 by Materials Project

description: Mg6Si5 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are twelve inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five Si+2.40- atoms to form MgSi5 trigonal bipyramids that share corners with five MgSi4 tetrahedra, corners with two equivalent MgSi5 trigonal bipyramids, edges with two equivalent MgSi6 octahedra, edges with five MgSi4 tetrahedra, and edges with three MgSi5 trigonal bipyramids. There are four shorter (2.87 Å) and one longer (3.00 Å) Mg–Si bond lengths. In the second Mg2+ site, Mg2+ is bonded in a 4-coordinate geometry to six Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.70–3.06 Å. In the third Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.83–3.06 Å. In the fourth Mg2+ site, Mg2+ is bonded in a 7-coordinate geometry to seven Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.94–3.03 Å. In the fifth Mg2+ site, Mg2+ is bonded to five Si+2.40- atoms to form distorted MgSi5 trigonal bipyramids that share corners with two equivalent MgSi4 tetrahedra, corners with two equivalent MgSi5 trigonal bipyramids, edges with two equivalent MgSi4 tetrahedra, and edges with three MgSi5 trigonal bipyramids. There are a spread of Mg–Si bond distances ranging from 2.76–2.93 Å. In the sixth Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.74–3.03 Å. In the seventh Mg2+ site, Mg2+ is bonded in a 1-coordinate geometry to eight Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.63–3.10 Å. In the eighth Mg2+ site, Mg2+ is bonded in a 7-coordinate geometry to seven Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.88–3.06 Å. In the ninth Mg2+ site, Mg2+ is bonded to four Si+2.40- atoms to form MgSi4 tetrahedra that share corners with two equivalent MgSi6 octahedra, corners with seven MgSi4 tetrahedra, an edgeedge with one MgSi6 octahedra, an edgeedge with one MgSi4 tetrahedra, and edges with four MgSi5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 27°. There are a spread of Mg–Si bond distances ranging from 2.74–2.79 Å. In the tenth Mg2+ site, Mg2+ is bonded to four Si+2.40- atoms to form MgSi4 tetrahedra that share corners with two equivalent MgSi6 octahedra, corners with four MgSi4 tetrahedra, corners with three equivalent MgSi5 trigonal bipyramids, edges with two equivalent MgSi6 octahedra, edges with two equivalent MgSi4 tetrahedra, and an edgeedge with one MgSi5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 53°. There are a spread of Mg–Si bond distances ranging from 2.73–2.80 Å. In the eleventh Mg2+ site, Mg2+ is bonded to six Si+2.40- atoms to form distorted MgSi6 octahedra that share corners with seven MgSi4 tetrahedra, edges with two equivalent MgSi6 octahedra, edges with four MgSi4 tetrahedra, and edges with two equivalent MgSi5 trigonal bipyramids. There are a spread of Mg–Si bond distances ranging from 2.86–3.08 Å. In the twelfth Mg2+ site, Mg2+ is bonded to four Si+2.40- atoms to form distorted MgSi4 tetrahedra that share corners with three equivalent MgSi6 octahedra, corners with five MgSi4 tetrahedra, corners with four MgSi5 trigonal bipyramids, an edgeedge with one MgSi6 octahedra, edges with three MgSi4 tetrahedra, and edges with two equivalent MgSi5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 29–47°. There are a spread of Mg–Si bond distances ranging from 2.69–2.77 Å. There are ten inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to six Mg2+ and three Si+2.40- atoms. There are one shorter (2.42 Å) and two longer (2.54 Å) Si–Si bond lengths. In the second Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to six Mg2+ and three Si+2.40- atoms. There are one shorter (2.41 Å) and one longer (2.49 Å) Si–Si bond lengths. In the third Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to nine Mg2+ atoms. In the fourth Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to eight Mg2+ and one Si+2.40- atom. The Si–Si bond length is 2.43 Å. In the fifth Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to eight Mg2+ and one Si+2.40- atom. The Si–Si bond length is 2.51 Å. In the sixth Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to four Mg2+ and three Si+2.40- atoms. Both Si–Si bond lengths are 2.57 Å. In the seventh Si+2.40- site, Si+2.40- is bonded in a 1-coordinate geometry to five Mg2+ and two equivalent Si+2.40- atoms. In the eighth Si+2.40- site, Si+2.40- is bonded in a distorted q6 geometry to five Mg2+ and four Si+2.40- atoms. In the ninth Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to nine Mg2+ atoms. In the tenth Si+2.40- site, Si+2.40- is bonded in a 1-coordinate geometry to eight Mg2+ and one Si+2.40- atom.