BiAlO3 crystallizes in the hexagonal P6_3cm space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1) and three equivalent O(3) atoms to form distorted AlO4 tetrahedra that share corners with three equivalent Al(1)O4 tetrahedra and corners with six equivalent Bi(1)O5 trigonal bipyramids. In the second Al site, Al(2) is bonded to one O(2) and three equivalent O(4) atoms to form AlO4 tetrahedra that share corners with six equivalent Bi(1)O5 trigonal bipyramids. Bi(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form BiO5 trigonal bipyramids that share corners with two equivalent Al(2)O4 tetrahedra, corners with four equivalent Al(1)O4 tetrahedra, and corners with six equivalent Bi(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Al(1) and three equivalent Bi(1) atoms to form corner-sharing OAlBi3 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Al(2) and three equivalent Bi(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Al(1) and one Bi(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Al(2) and one Bi(1) atom.
BiAlO3 crystallizes in the hexagonal P6_3cm space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1) and three equivalent O(3) atoms to form distorted AlO4 tetrahedra that share corners with three equivalent Al(1)O4 tetrahedra and corners with six equivalent Bi(1)O5 trigonal bipyramids. The Al(1)-O(1) bond length is 2.02 Å. All Al(1)-O(3) bond lengths are 2.00 Å. In the second Al site, Al(2) is bonded to one O(2) and three equivalent O(4) atoms to form AlO4 tetrahedra that share corners with six equivalent Bi(1)O5 trigonal bipyramids. The Al(2)-O(2) bond length is 1.84 Å. All Al(2)-O(4) bond lengths are 1.76 Å. Bi(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form BiO5 trigonal bipyramids that share corners with two equivalent Al(2)O4 tetrahedra, corners with four equivalent Al(1)O4 tetrahedra, and corners with six equivalent Bi(1)O5 trigonal bipyramids. The Bi(1)-O(2) bond length is 2.39 Å. The Bi(1)-O(3) bond length is 2.37 Å. The Bi(1)-O(4) bond length is 2.17 Å. Both Bi(1)-O(1) bond lengths are 2.32 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Al(1) and three equivalent Bi(1) atoms to form corner-sharing OAlBi3 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Al(2) and three equivalent Bi(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Al(1) and one Bi(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Al(2) and one Bi(1) atom.