BaAl2Sb2O7 crystallizes in the trigonal R32 space group. Ba(1) is bonded to six equivalent O(1) atoms to form distorted BaO6 pentagonal pyramids that share corners with six equivalent Al(1)O4 tetrahedra. Al(1) is bonded to one O(2) and three equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent Ba(1)O6 pentagonal pyramids and  a cornercorner with one Al(1)O4 tetrahedra. Sb(1) is bonded in a distorted T-shaped geometry to three equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ba(1), one Al(1), and one Sb(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Al(1) atoms.
BaAl2Sb2O7 crystallizes in the trigonal R32 space group. Ba(1) is bonded to six equivalent O(1) atoms to form distorted BaO6 pentagonal pyramids that share corners with six equivalent Al(1)O4 tetrahedra. All Ba(1)-O(1) bond lengths are 2.82 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 Ba(1)O6 pentagonal pyramids and  a cornercorner with one Al(1)O4 tetrahedra. The Al(1)-O(2) bond length is 1.73 Å. All Al(1)-O(1) bond lengths are 1.79 Å. Sb(1) is bonded in a distorted T-shaped geometry to three equivalent O(1) atoms. All Sb(1)-O(1) bond lengths are 1.98 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ba(1), one Al(1), and one Sb(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Al(1) atoms.