Ba2Ag3AlO8 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(2) and four equivalent O(3) atoms to form distorted BaO8 hexagonal bipyramids that share corners with eight equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent Ag(1)O5 trigonal bipyramids, faces with five equivalent Ba(1)O8 hexagonal bipyramids, and faces with four equivalent Ag(2)O6 octahedra. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted AgO5 trigonal bipyramids that share corners with four equivalent Ba(1)O8 hexagonal bipyramids,  a cornercorner with one Ag(2)O6 octahedra, and corners with four equivalent Ag(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. In the second Ag site, Ag(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form AgO6 octahedra that share corners with four equivalent Ag(2)O6 octahedra, corners with two equivalent Ag(1)O5 trigonal bipyramids, and faces with eight equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedra are not tilted. 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 in a distorted see-saw-like geometry to two equivalent Ag(1) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded to four equivalent Ba(1) and two equivalent Ag(2) atoms to form a mixture of distorted edge, face, and corner-sharing OBa4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 0-58°. In the third O site, O(3) is bonded to four equivalent Ba(1), one Ag(1), and one Ag(2) atom to form a mixture of edge, face, and corner-sharing OBa4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 0-58°.
Ba2Ag3AlO8 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(2) and four equivalent O(3) atoms to form distorted BaO8 hexagonal bipyramids that share corners with eight equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent Ag(1)O5 trigonal bipyramids, faces with five equivalent Ba(1)O8 hexagonal bipyramids, and faces with four equivalent Ag(2)O6 octahedra. All Ba(1)-O(2) bond lengths are 2.84 Å. All Ba(1)-O(3) bond lengths are 2.84 Å. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted AgO5 trigonal bipyramids that share corners with four equivalent Ba(1)O8 hexagonal bipyramids,  a cornercorner with one Ag(2)O6 octahedra, and corners with four equivalent Ag(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. The Ag(1)-O(3) bond length is 2.43 Å. All Ag(1)-O(1) bond lengths are 2.10 Å. In the second Ag site, Ag(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form AgO6 octahedra that share corners with four equivalent Ag(2)O6 octahedra, corners with two equivalent Ag(1)O5 trigonal bipyramids, and faces with eight equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedra are not tilted. Both Ag(2)-O(3) bond lengths are 2.11 Å. All Ag(2)-O(2) bond lengths are 2.01 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 2.34 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Ag(1) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded to four equivalent Ba(1) and two equivalent Ag(2) atoms to form a mixture of distorted edge, face, and corner-sharing OBa4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 0-58°. In the third O site, O(3) is bonded to four equivalent Ba(1), one Ag(1), and one Ag(2) atom to form a mixture of edge, face, and corner-sharing OBa4Ag2 octahedra. The corner-sharing octahedral tilt angles range from 0-58°.