Ba6Rh4Al2O15 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(1), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(5), and four equivalent O(2) atoms. In the third Ba site, Ba(3) is bonded in a 10-coordinate geometry to two equivalent O(1), four equivalent O(2), and four equivalent O(5) 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(3) atoms. There are two inequivalent Rh sites. In the first Rh site, Rh(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(5) atoms to form distorted RhO5 square pyramids that share corners with three equivalent Rh(2)O6 octahedra and  an edgeedge with one Rh(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 9-12°. In the second Rh site, Rh(2) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form RhO6 octahedra that share corners with three equivalent Rh(1)O5 square pyramids and corners with three equivalent Al(1)O4 tetrahedra. Al(1) is bonded to one O(4), one O(6), and two equivalent O(3) atoms to form AlO4 tetrahedra that share corners with three equivalent Rh(2)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-34°. There are six inequivalent O sites. In the first O site, O(4) is bonded in a 1-coordinate geometry to one Ba(4), two equivalent Ba(1), one Rh(2), and one Al(1) atom. In the second O site, O(5) is bonded to two equivalent Ba(2), two equivalent Ba(3), and two equivalent Rh(1) atoms to form a mixture of distorted corner and face-sharing OBa4Rh2 octahedra. The corner-sharing octahedral tilt angles range from 6-65°. In the third O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(4) and two equivalent Al(1) atoms. In the fourth O site, O(1) is bonded to one Ba(1), one Ba(3), two equivalent Ba(2), one Rh(1), and one Rh(2) atom to form a mixture of distorted corner and face-sharing OBa4Rh2 octahedra. The corner-sharing octahedral tilt angles range from 11-65°. In the fifth O site, O(2) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Rh(1), and one Rh(2) atom. In the sixth O site, O(3) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(4), two equivalent Ba(1), one Rh(2), and one Al(1) atom.
Ba6Rh4Al2O15 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(1), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. The Ba(1)-O(1) bond length is 2.83 Å. Both Ba(1)-O(2) bond lengths are 2.64 Å. Both Ba(1)-O(4) bond lengths are 2.95 Å. There are two shorter (2.87 Å) and two longer (3.01 Å) Ba(1)-O(3) bond lengths. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(5), and four equivalent O(2) atoms. Both Ba(2)-O(1) bond lengths are 2.87 Å. Both Ba(2)-O(3) bond lengths are 3.12 Å. Both Ba(2)-O(5) bond lengths are 2.94 Å. There are two shorter (2.79 Å) and two longer (3.08 Å) Ba(2)-O(2) bond lengths. In the third Ba site, Ba(3) is bonded in a 10-coordinate geometry to two equivalent O(1), four equivalent O(2), and four equivalent O(5) atoms. Both Ba(3)-O(1) bond lengths are 2.83 Å. All Ba(3)-O(2) bond lengths are 3.11 Å. There are two shorter (2.88 Å) and two longer (2.98 Å) Ba(3)-O(5) bond lengths. 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(3) atoms. Both Ba(4)-O(4) bond lengths are 2.67 Å. Both Ba(4)-O(6) bond lengths are 3.03 Å. All Ba(4)-O(3) bond lengths are 2.90 Å. There are two inequivalent Rh sites. In the first Rh site, Rh(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(5) atoms to form distorted RhO5 square pyramids that share corners with three equivalent Rh(2)O6 octahedra and  an edgeedge with one Rh(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 9-12°. The Rh(1)-O(1) bond length is 2.40 Å. Both Rh(1)-O(2) bond lengths are 2.02 Å. Both Rh(1)-O(5) bond lengths are 2.02 Å. In the second Rh site, Rh(2) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form RhO6 octahedra that share corners with three equivalent Rh(1)O5 square pyramids and corners with three equivalent Al(1)O4 tetrahedra. The Rh(2)-O(1) bond length is 1.98 Å. The Rh(2)-O(4) bond length is 2.46 Å. Both Rh(2)-O(2) bond lengths are 2.03 Å. Both Rh(2)-O(3) bond lengths are 2.06 Å. Al(1) is bonded to one O(4), one O(6), and two equivalent O(3) atoms to form AlO4 tetrahedra that share corners with three equivalent Rh(2)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-34°. The Al(1)-O(4) bond length is 1.76 Å. The Al(1)-O(6) bond length is 1.77 Å. Both Al(1)-O(3) bond lengths are 1.76 Å. There are six inequivalent O sites. In the first O site, O(4) is bonded in a 1-coordinate geometry to one Ba(4), two equivalent Ba(1), one Rh(2), and one Al(1) atom. In the second O site, O(5) is bonded to two equivalent Ba(2), two equivalent Ba(3), and two equivalent Rh(1) atoms to form a mixture of distorted corner and face-sharing OBa4Rh2 octahedra. The corner-sharing octahedral tilt angles range from 6-65°. In the third O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(4) and two equivalent Al(1) atoms. In the fourth O site, O(1) is bonded to one Ba(1), one Ba(3), two equivalent Ba(2), one Rh(1), and one Rh(2) atom to form a mixture of distorted corner and face-sharing OBa4Rh2 octahedra. The corner-sharing octahedral tilt angles range from 11-65°. In the fifth O site, O(2) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), one Rh(1), and one Rh(2) atom. In the sixth O site, O(3) is bonded in a 2-coordinate geometry to one Ba(2), one Ba(4), two equivalent Ba(1), one Rh(2), and one Al(1) atom.