Materials Data on Mg2Ni2O5 by Materials Project
Mg2Ni2O5 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Mg2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Mg–O bond distances ranging from 2.09–2.72 Å. Ni3+ is bonded to five O2- atoms to form corner-sharing NiO5 square pyramids. There are a spread of Ni–O bond distances ranging from 1.90–1.99 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Mg2+ and two equivalent Ni3+ atoms to form distorted OMg4Ni2 octahedra that share corners with eight equivalent OMg2Ni2 tetrahedra, edges with two equivalent OMg4Ni2 octahedra, and edges with two equivalent OMg2Ni2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Mg2+ and two equivalent Ni3+ atoms to form OMg2Ni2 tetrahedra that share corners with four equivalent OMg4Ni2 octahedra, corners with four equivalent OMg2Ni2 tetrahedra, and an edgeedge with one OMg4Ni2 octahedra. The corner-sharing octahedra tilt angles range from 19–61°. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Mg2+ and two equivalent Ni3+ atoms.