AlNbO4 crystallizes in the monoclinic C2/m space group. Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. Al(1) is bonded to one O(1), one O(3), one O(4), and three equivalent O(2) atoms to form a mixture of corner and edge-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 24°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Nb(1) and one Al(1) atom. In the second O site, O(2) is bonded to one Nb(1) and three equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing ONbAl3 trigonal pyramids. In the third O site, O(3) is bonded in a linear geometry to one Nb(1) and one Al(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Nb(1) and one Al(1) atom.
AlNbO4 crystallizes in the monoclinic C2/m space group. Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. The Nb(1)-O(2) bond length is 2.21 Å. The Nb(1)-O(3) bond length is 1.81 Å. Both Nb(1)-O(1) bond lengths are 1.98 Å. There is one shorter (1.89 Å) and one longer (2.33 Å) Nb(1)-O(4) bond length. Al(1) is bonded to one O(1), one O(3), one O(4), and three equivalent O(2) atoms to form a mixture of corner and edge-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 24°. The Al(1)-O(1) bond length is 1.93 Å. The Al(1)-O(3) bond length is 1.84 Å. The Al(1)-O(4) bond length is 1.85 Å. There are two shorter (1.94 Å) and one longer (1.96 Å) Al(1)-O(2) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Nb(1) and one Al(1) atom. In the second O site, O(2) is bonded to one Nb(1) and three equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing ONbAl3 trigonal pyramids. In the third O site, O(3) is bonded in a linear geometry to one Nb(1) and one Al(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Nb(1) and one Al(1) atom.