Ba6Dy2Al4O15 crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(7), two equivalent O(2), two equivalent O(5), and four equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(6), and four equivalent O(2) atoms. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one O(7), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to two equivalent O(4), two equivalent O(6), and four equivalent O(2) atoms. Dy(1) is bonded to one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form DyO6 octahedra that share corners with three equivalent Al(1)O4 tetrahedra and corners with three equivalent Al(2)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(5), and two equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent Dy(1)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 6-28°. In the second Al site, Al(2) is bonded to one O(4), one O(6), and two equivalent O(2) atoms to form AlO4 tetrahedra that share corners with three equivalent Dy(1)O6 octahedra and  a cornercorner with one Al(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 15-38°. There are seven inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Ba(3) and two equivalent Al(1) atoms. In the second O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Ba(4) and two equivalent Al(2) atoms. In the third O site, O(5) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Dy(1), and one Al(1) atom. In the fourth O site, O(6) is bonded in a 5-coordinate geometry to one Ba(4), two equivalent Ba(2), one Dy(1), and one Al(2) atom. In the fifth O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Ba(3) and two equivalent Ba(1) atoms. In the sixth O site, O(1) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Dy(1), and one Al(1) atom. In the seventh O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(4), two equivalent Ba(2), one Dy(1), and one Al(2) atom.
Ba6Dy2Al4O15 crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(7), two equivalent O(2), two equivalent O(5), and four equivalent O(1) atoms. The Ba(1)-O(7) bond length is 2.39 Å. Both Ba(1)-O(2) bond lengths are 3.17 Å. Both Ba(1)-O(5) bond lengths are 2.99 Å. There are two shorter (2.94 Å) and two longer (3.03 Å) Ba(1)-O(1) bond lengths. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(6), and four equivalent O(2) atoms. The Ba(2)-O(5) bond length is 3.24 Å. Both Ba(2)-O(1) bond lengths are 2.72 Å. Both Ba(2)-O(6) bond lengths are 3.05 Å. There are two shorter (2.86 Å) and two longer (3.11 Å) Ba(2)-O(2) bond lengths. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one O(7), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms. The Ba(3)-O(7) bond length is 2.49 Å. Both Ba(3)-O(3) bond lengths are 3.13 Å. Both Ba(3)-O(5) bond lengths are 2.94 Å. All Ba(3)-O(1) bond lengths are 3.10 Å. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to two equivalent O(4), two equivalent O(6), and four equivalent O(2) atoms. Both Ba(4)-O(4) bond lengths are 3.16 Å. Both Ba(4)-O(6) bond lengths are 2.70 Å. All Ba(4)-O(2) bond lengths are 2.96 Å. Dy(1) is bonded to one O(5), one O(6), two equivalent O(1), and two equivalent O(2) atoms to form DyO6 octahedra that share corners with three equivalent Al(1)O4 tetrahedra and corners with three equivalent Al(2)O4 tetrahedra. The Dy(1)-O(5) bond length is 2.24 Å. The Dy(1)-O(6) bond length is 2.38 Å. Both Dy(1)-O(1) bond lengths are 2.25 Å. Both Dy(1)-O(2) bond lengths are 2.28 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(5), and two equivalent O(1) atoms to form AlO4 tetrahedra that share corners with three equivalent Dy(1)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 6-28°. The Al(1)-O(3) bond length is 1.76 Å. The Al(1)-O(5) bond length is 1.77 Å. Both Al(1)-O(1) bond lengths are 1.81 Å. In the second Al site, Al(2) is bonded to one O(4), one O(6), and two equivalent O(2) atoms to form AlO4 tetrahedra that share corners with three equivalent Dy(1)O6 octahedra and  a cornercorner with one Al(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 15-38°. The Al(2)-O(4) bond length is 1.77 Å. The Al(2)-O(6) bond length is 1.78 Å. Both Al(2)-O(2) bond lengths are 1.78 Å. There are seven inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Ba(3) and two equivalent Al(1) atoms. In the second O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Ba(4) and two equivalent Al(2) atoms. In the third O site, O(5) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Dy(1), and one Al(1) atom. In the fourth O site, O(6) is bonded in a 5-coordinate geometry to one Ba(4), two equivalent Ba(2), one Dy(1), and one Al(2) atom. In the fifth O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Ba(3) and two equivalent Ba(1) atoms. In the sixth O site, O(1) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Dy(1), and one Al(1) atom. In the seventh O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(4), two equivalent Ba(2), one Dy(1), and one Al(2) atom.