Ba2Co3AlO8 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted corner-sharing CoO5 trigonal bipyramids. In the second Co site, Co(2) is bonded in a square co-planar geometry to four equivalent O(2) atoms. Al(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Co(1) and two equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing OAl2Co2 tetrahedra. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ba(1) and two equivalent Co(2) atoms. In the third O site, O(3) is bonded in a 1-coordinate geometry to four equivalent Ba(1) and one Co(1) atom.
Ba2Co3AlO8 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. All Ba(1)-O(2) bond lengths are 2.83 Å. All Ba(1)-O(3) bond lengths are 2.74 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted corner-sharing CoO5 trigonal bipyramids. The Co(1)-O(3) bond length is 1.81 Å. All Co(1)-O(1) bond lengths are 1.98 Å. In the second Co site, Co(2) is bonded in a square co-planar geometry to four equivalent O(2) atoms. All Co(2)-O(2) bond lengths are 1.88 Å. Al(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Al(1)-O(1) bond lengths are 2.23 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Co(1) and two equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing OAl2Co2 tetrahedra. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ba(1) and two equivalent Co(2) atoms. In the third O site, O(3) is bonded in a 1-coordinate geometry to four equivalent Ba(1) and one Co(1) atom.