Ba3TiAl10O20 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(4) and four equivalent O(2) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), and four equivalent O(5) atoms. Ti(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form TiO6 octahedra that share corners with four equivalent Al(1)O4 tetrahedra and edges with four equivalent Al(2)O6 octahedra. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and corners with three equivalent Al(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-64°. In the second Al site, Al(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with two equivalent Al(3)O4 tetrahedra, corners with four equivalent Al(1)O4 tetrahedra,  an edgeedge with one Al(2)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. In the third Al site, Al(3) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra,  a cornercorner with one Al(3)O4 tetrahedra, and corners with three equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. There are six inequivalent O sites. In the first O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ba(2), one Al(1), and one Al(3) atom. In the second O site, O(3) is bonded to one Ba(2), one Ti(1), and two equivalent Al(2) atoms to form a mixture of distorted corner and edge-sharing OBaTiAl2 tetrahedra. In the third O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Al(3) atoms. In the fourth O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Al(1), and one Al(3) atom. In the fifth O site, O(6) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the sixth O site, O(1) is bonded in a 3-coordinate geometry to one Ba(2), one Ti(1), one Al(1), and one Al(2) atom.
Ba3TiAl10O20 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to two equivalent O(4) and four equivalent O(2) atoms. Both Ba(1)-O(4) bond lengths are 2.69 Å. All Ba(1)-O(2) bond lengths are 2.80 Å. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), and four equivalent O(5) atoms. The Ba(2)-O(3) bond length is 2.60 Å. Both Ba(2)-O(1) bond lengths are 3.03 Å. Both Ba(2)-O(2) bond lengths are 2.79 Å. There are two shorter (2.85 Å) and two longer (3.18 Å) Ba(2)-O(5) bond lengths. Ti(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form TiO6 octahedra that share corners with four equivalent Al(1)O4 tetrahedra and edges with four equivalent Al(2)O6 octahedra. Both Ti(1)-O(3) bond lengths are 1.92 Å. All Ti(1)-O(1) bond lengths are 1.99 Å. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and corners with three equivalent Al(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-64°. The Al(1)-O(1) bond length is 1.79 Å. The Al(1)-O(2) bond length is 1.76 Å. The Al(1)-O(5) bond length is 1.75 Å. The Al(1)-O(6) bond length is 1.82 Å. In the second Al site, Al(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with two equivalent Al(3)O4 tetrahedra, corners with four equivalent Al(1)O4 tetrahedra,  an edgeedge with one Al(2)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. Both Al(2)-O(1) bond lengths are 1.93 Å. Both Al(2)-O(3) bond lengths are 2.01 Å. Both Al(2)-O(6) bond lengths are 1.94 Å. In the third Al site, Al(3) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra,  a cornercorner with one Al(3)O4 tetrahedra, and corners with three equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. The Al(3)-O(2) bond length is 1.77 Å. The Al(3)-O(4) bond length is 1.77 Å. The Al(3)-O(5) bond length is 1.76 Å. The Al(3)-O(6) bond length is 1.82 Å. There are six inequivalent O sites. In the first O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ba(2), one Al(1), and one Al(3) atom. In the second O site, O(3) is bonded to one Ba(2), one Ti(1), and two equivalent Al(2) atoms to form a mixture of distorted corner and edge-sharing OBaTiAl2 tetrahedra. In the third O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Al(3) atoms. In the fourth O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Al(1), and one Al(3) atom. In the fifth O site, O(6) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the sixth O site, O(1) is bonded in a 3-coordinate geometry to one Ba(2), one Ti(1), one Al(1), and one Al(2) atom.