FeNiO3 is Ilmenite structured and crystallizes in the trigonal R3 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with six equivalent Ni(1)O6 octahedra, edges with three equivalent Fe(2)O6 octahedra, and  a faceface with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-60°. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form FeO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with six equivalent Ni(2)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, and  a faceface with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NiO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with six equivalent Fe(1)O6 octahedra, edges with three equivalent Ni(2)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-60°. In the second Ni site, Ni(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form NiO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with six equivalent Fe(2)O6 octahedra, edges with three equivalent Ni(1)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Fe(1), one Fe(2), one Ni(1), and one Ni(2) atom to form a mixture of distorted edge and corner-sharing OFe2Ni2 trigonal pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Ni(1), and one Ni(2) atom.
FeNiO3 is Ilmenite structured and crystallizes in the trigonal R3 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with six equivalent Ni(1)O6 octahedra, edges with three equivalent Fe(2)O6 octahedra, and  a faceface with one Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-60°. All Fe(1)-O(1) bond lengths are 1.96 Å. All Fe(1)-O(2) bond lengths are 2.08 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form FeO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with six equivalent Ni(2)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, and  a faceface with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. All Fe(2)-O(1) bond lengths are 2.02 Å. All Fe(2)-O(2) bond lengths are 1.93 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NiO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with six equivalent Fe(1)O6 octahedra, edges with three equivalent Ni(2)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-60°. All Ni(1)-O(1) bond lengths are 2.11 Å. All Ni(1)-O(2) bond lengths are 2.04 Å. In the second Ni site, Ni(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form NiO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with six equivalent Fe(2)O6 octahedra, edges with three equivalent Ni(1)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. All Ni(2)-O(1) bond lengths are 2.01 Å. All Ni(2)-O(2) bond lengths are 2.07 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Fe(1), one Fe(2), one Ni(1), and one Ni(2) atom to form a mixture of distorted edge and corner-sharing OFe2Ni2 trigonal pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Ni(1), and one Ni(2) atom.