Materials Data on MgAl2O4 by Materials Project

Abstract

MgAl2O4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Mg2+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.04–2.58 Å. Al3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing AlO6 octahedra. The corner-sharing octahedra tilt angles range from 0–51°. There are a spread of Al–O bond distances ranging from 1.85–2.00 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Al3+ atoms to form distorted OMg2Al3 trigonal bipyramids that share corners with five equivalent OMg2Al2 tetrahedra, corners with two equivalent OMg2Al3 trigonal bipyramids, an edgeedge with one OMg2Al2 tetrahedra, and edges with five equivalent OMg2Al3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and two equivalent Al3+ atoms to form distorted OMg2Al2 tetrahedra that share corners with two equivalent OMg2Al2 tetrahedra, corners with ten equivalent OMg2Al3 trigonal bipyramids, and edges with two equivalent OMg2Al3 trigonal bipyramids. In the third O2- site, O2- is bonded in a distorted square co-planar geometry to two equivalent Mg2+ and four equivalent Al3+ atoms.