Materials Data on Mg2AsO5 by Materials Project

Abstract

Mg2AsO5 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four equivalent AsO4 tetrahedra, corners with four equivalent MgO5 trigonal bipyramids, and edges with two equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.19 Å. In the second Mg site, Mg is bonded to five O atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent MgO6 octahedra, corners with four equivalent AsO4 tetrahedra, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 50–65°. There are a spread of Mg–O bond distances ranging from 2.00–2.06 Å. As is bonded to four O atoms to form AsO4 tetrahedra that share corners with four equivalent MgO6 octahedra and corners with four equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 54–65°. All As–O bond lengths are 1.72 Å. There are four inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to two equivalent Mg and one As atom. In the second O site, O is bonded in a distorted trigonal planar geometry to three Mg atoms. In the third O site, O is bonded in a trigonal planar geometry to two equivalent Mg and one As atom. In the fourth O site, O is bonded in a trigonal planar geometry to two Mg and one As atom.