AlFe2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. In the second Fe site, Fe(2) is bonded to six equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra and edges with six equivalent Fe(1)O6 octahedra. Al(1) is bonded to one O(2) and three equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent Fe(2)O6 octahedra and corners with nine equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Al(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to three equivalent Fe(1) and one Al(1) atom.
AlFe2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. Both Fe(1)-O(2) bond lengths are 2.11 Å. All Fe(1)-O(1) bond lengths are 2.11 Å. In the second Fe site, Fe(2) is bonded to six equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra and edges with six equivalent Fe(1)O6 octahedra. All Fe(2)-O(1) bond lengths are 2.07 Å. Al(1) is bonded to one O(2) and three equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent Fe(2)O6 octahedra and corners with nine equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-55°. The Al(1)-O(2) bond length is 1.79 Å. All Al(1)-O(1) bond lengths are 1.82 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Al(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to three equivalent Fe(1) and one Al(1) atom.