Materials Data on Co2NiO4 by Materials Project
NiCo2O4 is Spinel-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six equivalent CoO6 octahedra and corners with six equivalent NiO6 octahedra. The corner-sharing octahedra tilt angles range from 56–60°. There is two shorter (1.86 Å) and two longer (1.94 Å) Co–O bond length. In the second Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent CoO4 tetrahedra, edges with two equivalent CoO6 octahedra, and edges with four equivalent NiO6 octahedra. There is two shorter (1.92 Å) and four longer (1.95 Å) Co–O bond length. Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with six equivalent CoO4 tetrahedra, edges with two equivalent NiO6 octahedra, and edges with four equivalent CoO6 octahedra. There are four shorter (2.02 Å) and two longer (2.04 Å) Ni–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two Co3+ and two equivalent Ni2+ atoms to form a mixture of distorted edge and corner-sharing OCo2Ni2 trigonal pyramids. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co3+ and one Ni2+ atom.