NiCo2O4 is Spinel-like structured and crystallizes in the triclinic P-1 space group. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. In the third Co site, Co(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. In the fourth Co site, Co(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. Ni(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form NiO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, corners with three equivalent Co(3)O6 octahedra, and corners with three equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-74°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Co(2), one Co(3), one Co(4), and one Ni(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Co(1), one Co(3), one Co(4), and one Ni(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(4), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one Ni(1) atom.
NiCo2O4 is Spinel-like structured and crystallizes in the triclinic P-1 space group. There are four inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(2)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. Both Co(1)-O(2) bond lengths are 1.93 Å. Both Co(1)-O(3) bond lengths are 2.03 Å. Both Co(1)-O(4) bond lengths are 2.07 Å. In the second Co site, Co(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(3)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. Both Co(2)-O(1) bond lengths are 1.93 Å. Both Co(2)-O(3) bond lengths are 2.06 Å. Both Co(2)-O(4) bond lengths are 2.03 Å. In the third Co site, Co(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(4)O6 octahedra. Both Co(3)-O(1) bond lengths are 1.98 Å. Both Co(3)-O(2) bond lengths are 2.20 Å. Both Co(3)-O(4) bond lengths are 1.87 Å. In the fourth Co site, Co(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CoO6 octahedra that share corners with six equivalent Ni(1)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. Both Co(4)-O(1) bond lengths are 2.19 Å. Both Co(4)-O(2) bond lengths are 1.99 Å. Both Co(4)-O(3) bond lengths are 1.87 Å. Ni(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form NiO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, corners with three equivalent Co(3)O6 octahedra, and corners with three equivalent Co(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-74°. The Ni(1)-O(1) bond length is 2.01 Å. The Ni(1)-O(2) bond length is 2.01 Å. The Ni(1)-O(3) bond length is 1.97 Å. The Ni(1)-O(4) bond length is 1.97 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Co(2), one Co(3), one Co(4), and one Ni(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Co(1), one Co(3), one Co(4), and one Ni(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(4), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Co(1), one Co(2), one Co(3), and one Ni(1) atom.