DOI: 10.17188/1732789
title: Materials Data on Mg6Si5 by Materials Project

description: Mg6Si5 crystallizes in the triclinic P1 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 distorted MgSi5 square pyramids that share corners with three equivalent MgSi6 octahedra, corners with two equivalent MgSi4 tetrahedra, corners with two equivalent MgSi5 trigonal bipyramids, an edgeedge with one MgSi6 octahedra, edges with two equivalent MgSi5 square pyramids, edges with six MgSi4 tetrahedra, and an edgeedge with one MgSi5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 45–56°. There are a spread of Mg–Si bond distances ranging from 2.89–3.05 Å. 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 2.68–3.11 Å. In the third Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to eight Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.88–3.13 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 2.85–3.01 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 MgSi5 square pyramids, corners with two equivalent MgSi4 tetrahedra, an edgeedge with one MgSi5 square pyramid, edges with two equivalent MgSi4 tetrahedra, and edges with two equivalent MgSi5 trigonal bipyramids. There are a spread of Mg–Si bond distances ranging from 2.69–2.95 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 2.83–3.07 Å. In the seventh Mg2+ site, Mg2+ is bonded in a 5-coordinate geometry to five Si+2.40- atoms. There are a spread of Mg–Si bond distances ranging from 2.84–2.87 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 2.79–3.05 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, edges with two equivalent MgSi5 square pyramids, edges with two MgSi4 tetrahedra, and edges with two equivalent MgSi5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 50°. There are one shorter (2.66 Å) and three longer (2.71 Å) Mg–Si bond lengths. In the tenth Mg2+ site, Mg2+ is bonded to six Si+2.40- atoms to form distorted MgSi6 octahedra that share corners with three equivalent MgSi5 square pyramids, corners with four MgSi4 tetrahedra, edges with two equivalent MgSi6 octahedra, an edgeedge with one MgSi5 square pyramid, and edges with four MgSi4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.79–3.01 Å. In the eleventh 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, edges with two equivalent MgSi6 octahedra, edges with two equivalent MgSi5 square pyramids, and edges with two MgSi4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of Mg–Si bond distances ranging from 2.58–2.73 Å. In the twelfth Mg2+ site, Mg2+ is bonded to four Si+2.40- atoms to form MgSi4 tetrahedra that share corners with two equivalent MgSi5 square pyramids, corners with eight MgSi4 tetrahedra, corners with two equivalent MgSi5 trigonal bipyramids, edges with two equivalent MgSi6 octahedra, edges with two equivalent MgSi5 square pyramids, and edges with two MgSi4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.69–2.76 Å. There are ten inequivalent Si+2.40- sites. In the first Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to four Mg2+ and three Si+2.40- atoms. There are a spread of Si–Si bond distances ranging from 2.33–2.49 Å. In the second Si+2.40- site, Si+2.40- is bonded in a 7-coordinate geometry to four Mg2+ and three Si+2.40- atoms. There are one shorter (2.33 Å) and one longer (2.41 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 2.48 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 2.50 Å. In the sixth Si+2.40- site, Si+2.40- is bonded in a 9-coordinate geometry to eight Mg2+ and one Si+2.40- atom. In the seventh Si+2.40- site, Si+2.40- is bonded in a 1-coordinate geometry to seven Mg2+ and two equivalent Si+2.40- atoms. Both Si–Si bond lengths are 2.40 Å. In the eighth Si+2.40- site, Si+2.40- is bonded in a 8-coordinate geometry to four 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 9-coordinate geometry to six Mg2+ and three Si+2.40- atoms.