Ni2FeO4 is Spinel structured and crystallizes in the trigonal R-3m space group. Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form FeO4 tetrahedra that share corners with three equivalent Ni(2)O6 octahedra and corners with nine equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 57°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the second Ni site, Ni(2) is bonded to six equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Fe(1)O4 tetrahedra and edges with six equivalent Ni(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Ni(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded to one Fe(1) and three equivalent Ni(1) atoms to form distorted corner-sharing OFeNi3 trigonal pyramids.
Ni2FeO4 is Spinel structured and crystallizes in the trigonal R-3m space group. Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form FeO4 tetrahedra that share corners with three equivalent Ni(2)O6 octahedra and corners with nine equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 57°. The Fe(1)-O(2) bond length is 1.90 Å. All Fe(1)-O(1) bond lengths are 1.91 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. Both Ni(1)-O(2) bond lengths are 2.02 Å. All Ni(1)-O(1) bond lengths are 2.06 Å. In the second Ni site, Ni(2) is bonded to six equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Fe(1)O4 tetrahedra and edges with six equivalent Ni(1)O6 octahedra. All Ni(2)-O(1) bond lengths are 2.00 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Ni(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded to one Fe(1) and three equivalent Ni(1) atoms to form distorted corner-sharing OFeNi3 trigonal pyramids.