Materials Data on Mg2Cr2O5 by Materials Project

Abstract

Mg2Cr2O5 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Mg2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.08–2.50 Å. Cr3+ is bonded to five O2- atoms to form corner-sharing CrO5 trigonal bipyramids. There are a spread of Cr–O bond distances ranging from 1.93–2.00 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Mg2+ and two equivalent Cr3+ atoms to form distorted OMg4Cr2 octahedra that share corners with eight equivalent OMg2Cr2 tetrahedra, corners with four equivalent OMg2Cr2 trigonal pyramids, edges with two equivalent OMg4Cr2 octahedra, edges with two equivalent OMg2Cr2 tetrahedra, and edges with four equivalent OMg2Cr2 trigonal pyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and two equivalent Cr3+ atoms to form distorted OMg2Cr2 tetrahedra that share corners with four equivalent OMg4Cr2 octahedra, corners with four equivalent OMg2Cr2 tetrahedra, corners with four equivalent OMg2Cr2 trigonal pyramids, an edgeedge with one OMg4Cr2 octahedra, and edges with two equivalent OMg2Cr2 trigonal pyramids. The corner-sharing octahedra tilt angles range from 18–60°. In the third O2- site, O2- is bonded to two equivalent Mg2+ and two equivalent Cr3+ atoms to form distorted OMg2Cr2 trigonal pyramids that share corners with two equivalent OMg4Cr2 octahedra, corners with four equivalent OMg2Cr2 tetrahedra, corners with two equivalent OMg2Cr2 trigonal pyramids, edges with two equivalent OMg4Cr2 octahedra, edges with two equivalent OMg2Cr2 tetrahedra, and an edgeedge with one OMg2Cr2 trigonal pyramid. The corner-sharing octahedral tilt angles are 58°.