NiCo2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to six equivalent O(2) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra and edges with six equivalent Co(2)O6 octahedra. In the second Co site, Co(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. Ni(1) is bonded to one O(1) and three equivalent O(2) atoms to form NiO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra and corners with nine equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-60°. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Co(2) and one Ni(1) atom to form a mixture of distorted corner and edge-sharing OCo3Ni tetrahedra. In the second O site, O(2) is bonded to one Co(1), two equivalent Co(2), and one Ni(1) atom to form a mixture of distorted corner and edge-sharing OCo3Ni trigonal pyramids.
NiCo2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to six equivalent O(2) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra and edges with six equivalent Co(2)O6 octahedra. All Co(1)-O(2) bond lengths are 1.93 Å. In the second Co site, Co(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. Both Co(2)-O(1) bond lengths are 1.91 Å. All Co(2)-O(2) bond lengths are 1.93 Å. Ni(1) is bonded to one O(1) and three equivalent O(2) atoms to form NiO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra and corners with nine equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-60°. The Ni(1)-O(1) bond length is 2.03 Å. All Ni(1)-O(2) bond lengths are 1.95 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Co(2) and one Ni(1) atom to form a mixture of distorted corner and edge-sharing OCo3Ni tetrahedra. In the second O site, O(2) is bonded to one Co(1), two equivalent Co(2), and one Ni(1) atom to form a mixture of distorted corner and edge-sharing OCo3Ni trigonal pyramids.