Materials Data on Mg2Si2O5 by Materials Project

Abstract

Mg2Si2O5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a body-centered cubic geometry to eight equivalent O atoms. All Mg–O bond lengths are 2.28 Å. In the second Mg site, Mg is bonded to twelve O atoms to form MgO12 cuboctahedra that share corners with four equivalent MgO12 cuboctahedra, faces with four equivalent MgO12 cuboctahedra, and faces with eight equivalent SiO5 square pyramids. There are eight shorter (2.49 Å) and four longer (2.58 Å) Mg–O bond lengths. Si is bonded to five O atoms to form SiO5 square pyramids that share corners with five equivalent SiO5 square pyramids and faces with four equivalent MgO12 cuboctahedra. There is one shorter (1.78 Å) and four longer (1.83 Å) Si–O bond length. There are two inequivalent O sites. In the first O site, O is bonded to four Mg and two equivalent Si atoms to form a mixture of distorted corner, edge, and face-sharing OMg4Si2 octahedra. The corner-sharing octahedra tilt angles range from 0–69°. In the second O site, O is bonded in a distorted linear geometry to four equivalent Mg and two equivalent Si atoms.