Ba2InAlO5 crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, faces with six equivalent In(1)O6 octahedra, and faces with two equivalent Al(1)O4 tetrahedra. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. In(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form InO6 octahedra that share corners with three equivalent In(1)O6 octahedra, corners with three equivalent Al(1)O4 tetrahedra, and faces with three equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Al(1) is bonded to one O(3) and three equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent In(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 19°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one In(1), and one Al(1) atom. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent In(1) atoms to form a mixture of distorted face and corner-sharing OBa4In2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the third O site, O(3) is bonded in a linear geometry to two equivalent Al(1) atoms.
Ba2InAlO5 crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. All Ba(1)-O(2) bond lengths are 2.72 Å. All Ba(1)-O(1) bond lengths are 3.02 Å. In the second Ba site, Ba(2) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, faces with six equivalent In(1)O6 octahedra, and faces with two equivalent Al(1)O4 tetrahedra. All Ba(2)-O(1) bond lengths are 3.17 Å. All Ba(2)-O(2) bond lengths are 2.97 Å. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. All Ba(3)-O(1) bond lengths are 2.90 Å. In(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form InO6 octahedra that share corners with three equivalent In(1)O6 octahedra, corners with three equivalent Al(1)O4 tetrahedra, and faces with three equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. All In(1)-O(1) bond lengths are 2.21 Å. All In(1)-O(2) bond lengths are 2.17 Å. Al(1) is bonded to one O(3) and three equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent In(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 19°. The Al(1)-O(3) bond length is 1.73 Å. All Al(1)-O(1) bond lengths are 1.77 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one In(1), and one Al(1) atom. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent In(1) atoms to form a mixture of distorted face and corner-sharing OBa4In2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the third O site, O(3) is bonded in a linear geometry to two equivalent Al(1) atoms.