FeCo3O8 is trigonal omega-derived structured and crystallizes in the tetragonal P4_3 space group. Fe(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form FeO6 octahedra that share 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. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CoO6 octahedra that share edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. In the second Co site, Co(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CoO6 octahedra that share edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. In the third Co site, Co(3) is bonded to one O(5), one O(7), two equivalent O(3), and two equivalent O(8) atoms to form CoO6 octahedra that share edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Fe(1) and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Co(2) and two equivalent Co(3) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(1), and one Co(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(2), and one Co(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Co(2) and two equivalent Co(1) atoms. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(2), and one Co(3) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Fe(1) and two equivalent Co(3) atoms.
FeCo3O8 is trigonal omega-derived structured and crystallizes in the tetragonal P4_3 space group. Fe(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form FeO6 octahedra that share 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. The Fe(1)-O(1) bond length is 1.89 Å. The Fe(1)-O(2) bond length is 1.89 Å. The Fe(1)-O(4) bond length is 1.88 Å. The Fe(1)-O(5) bond length is 1.89 Å. The Fe(1)-O(7) bond length is 1.89 Å. The Fe(1)-O(8) bond length is 1.89 Å. There are three inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CoO6 octahedra that share edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(2)O6 octahedra. The Co(1)-O(2) bond length is 1.90 Å. The Co(1)-O(4) bond length is 1.90 Å. There is one shorter (1.89 Å) and one longer (1.90 Å) Co(1)-O(1) bond length. Both Co(1)-O(6) bond lengths are 1.87 Å. In the second Co site, Co(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CoO6 octahedra that share edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. The Co(2)-O(2) bond length is 1.90 Å. The Co(2)-O(3) bond length is 1.87 Å. The Co(2)-O(4) bond length is 1.90 Å. The Co(2)-O(5) bond length is 1.90 Å. The Co(2)-O(6) bond length is 1.87 Å. The Co(2)-O(7) bond length is 1.90 Å. In the third Co site, Co(3) is bonded to one O(5), one O(7), two equivalent O(3), and two equivalent O(8) atoms to form CoO6 octahedra that share edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra, and edges with two equivalent Co(3)O6 octahedra. The Co(3)-O(5) bond length is 1.90 Å. The Co(3)-O(7) bond length is 1.90 Å. Both Co(3)-O(3) bond lengths are 1.87 Å. Both Co(3)-O(8) bond lengths are 1.90 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Fe(1) and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Co(2) and two equivalent Co(3) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(1), and one Co(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(2), and one Co(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Co(2) and two equivalent Co(1) atoms. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Fe(1), one Co(2), and one Co(3) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Fe(1) and two equivalent Co(3) atoms.