Fe4NiCdO8 is Spinel-derived structured and crystallizes in the trigonal R3m space group. There are two inequivalent Fe sites. In the first Fe site, 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(1)O6 octahedra and corners with nine equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. In the second Fe site, Fe(2) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra, corners with three equivalent Cd(1)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. Ni(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form NiO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra, corners with three equivalent Cd(1)O4 tetrahedra, and edges with six equivalent Fe(2)O6 octahedra. Cd(1) is bonded to one O(4) and three equivalent O(3) atoms to form CdO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with nine equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-62°. 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 Fe(1), two equivalent Fe(2), and one Ni(1) atom. In the second O site, O(2) is bonded to one Fe(1) and three equivalent Fe(2) atoms to form distorted OFe4 trigonal pyramids that share corners with six equivalent O(3)CdFe2Ni tetrahedra and corners with three equivalent O(4)CdFe3 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Fe(2), one Ni(1), and one Cd(1) atom to form distorted OCdFe2Ni tetrahedra that share corners with two equivalent O(3)CdFe2Ni tetrahedra,  a cornercorner with one O(4)CdFe3 trigonal pyramid, corners with two equivalent O(2)Fe4 trigonal pyramids, edges with two equivalent O(3)CdFe2Ni tetrahedra, and  an edgeedge with one O(4)CdFe3 trigonal pyramid. In the fourth O site, O(4) is bonded to three equivalent Fe(2) and one Cd(1) atom to form distorted OCdFe3 trigonal pyramids that share corners with three equivalent O(3)CdFe2Ni tetrahedra, corners with three equivalent O(2)Fe4 trigonal pyramids, and edges with three equivalent O(3)CdFe2Ni tetrahedra.
Fe4NiCdO8 is Spinel-derived structured and crystallizes in the trigonal R3m space group. There are two inequivalent Fe sites. In the first Fe site, 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(1)O6 octahedra and corners with nine equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. The Fe(1)-O(2) bond length is 2.01 Å. All Fe(1)-O(1) bond lengths are 1.96 Å. In the second Fe site, Fe(2) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra, corners with three equivalent Cd(1)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The Fe(2)-O(2) bond length is 2.13 Å. The Fe(2)-O(4) bond length is 2.02 Å. Both Fe(2)-O(1) bond lengths are 2.12 Å. Both Fe(2)-O(3) bond lengths are 1.99 Å. Ni(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form NiO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra, corners with three equivalent Cd(1)O4 tetrahedra, and edges with six equivalent Fe(2)O6 octahedra. All Ni(1)-O(1) bond lengths are 2.16 Å. All Ni(1)-O(3) bond lengths are 2.06 Å. Cd(1) is bonded to one O(4) and three equivalent O(3) atoms to form CdO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with nine equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-62°. The Cd(1)-O(4) bond length is 2.14 Å. All Cd(1)-O(3) bond lengths are 2.13 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 Fe(1), two equivalent Fe(2), and one Ni(1) atom. In the second O site, O(2) is bonded to one Fe(1) and three equivalent Fe(2) atoms to form distorted OFe4 trigonal pyramids that share corners with six equivalent O(3)CdFe2Ni tetrahedra and corners with three equivalent O(4)CdFe3 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Fe(2), one Ni(1), and one Cd(1) atom to form distorted OCdFe2Ni tetrahedra that share corners with two equivalent O(3)CdFe2Ni tetrahedra,  a cornercorner with one O(4)CdFe3 trigonal pyramid, corners with two equivalent O(2)Fe4 trigonal pyramids, edges with two equivalent O(3)CdFe2Ni tetrahedra, and  an edgeedge with one O(4)CdFe3 trigonal pyramid. In the fourth O site, O(4) is bonded to three equivalent Fe(2) and one Cd(1) atom to form distorted OCdFe3 trigonal pyramids that share corners with three equivalent O(3)CdFe2Ni tetrahedra, corners with three equivalent O(2)Fe4 trigonal pyramids, and edges with three equivalent O(3)CdFe2Ni tetrahedra.