Ba5Cu2Al3 crystallizes in the trigonal R3m space group. There are five inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 3-coordinate geometry to three equivalent Ba(2), three equivalent Cu(1), and three equivalent Al(1) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Ba(3), three equivalent Ba(1), one Cu(1), and three equivalent Cu(2) atoms. In the third Ba site, Ba(3) is bonded in a distorted trigonal non-coplanar geometry to one Ba(2), three equivalent Ba(4), three equivalent Cu(2), and three equivalent Al(1) atoms. In the fourth Ba site, Ba(4) is bonded in a 12-coordinate geometry to three equivalent Ba(3), three equivalent Cu(2), and six equivalent Al(1) atoms. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to three equivalent Cu(1) and six equivalent Al(1) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 10-coordinate geometry to one Ba(2), three equivalent Ba(1), three equivalent Ba(5), and three equivalent Al(1) atoms. In the second Cu site, Cu(2) is bonded in a 9-coordinate geometry to three equivalent Ba(2), three equivalent Ba(3), and three equivalent Ba(4) atoms. Al(1) is bonded in a 11-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(4), two equivalent Ba(5), one Cu(1), and four equivalent Al(1) atoms.
Ba5Cu2Al3 crystallizes in the trigonal R3m space group. There are five inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 3-coordinate geometry to three equivalent Ba(2), three equivalent Cu(1), and three equivalent Al(1) atoms. All Ba(1)-Ba(2) bond lengths are 4.14 Å. All Ba(1)-Cu(1) bond lengths are 3.47 Å. All Ba(1)-Al(1) bond lengths are 3.68 Å. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Ba(3), three equivalent Ba(1), one Cu(1), and three equivalent Cu(2) atoms. The Ba(2)-Ba(3) bond length is 3.61 Å. The Ba(2)-Cu(1) bond length is 3.74 Å. All Ba(2)-Cu(2) bond lengths are 4.11 Å. In the third Ba site, Ba(3) is bonded in a distorted trigonal non-coplanar geometry to one Ba(2), three equivalent Ba(4), three equivalent Cu(2), and three equivalent Al(1) atoms. All Ba(3)-Ba(4) bond lengths are 3.50 Å. All Ba(3)-Cu(2) bond lengths are 3.44 Å. All Ba(3)-Al(1) bond lengths are 3.69 Å. In the fourth Ba site, Ba(4) is bonded in a 12-coordinate geometry to three equivalent Ba(3), three equivalent Cu(2), and six equivalent Al(1) atoms. All Ba(4)-Cu(2) bond lengths are 4.03 Å. All Ba(4)-Al(1) bond lengths are 3.49 Å. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to three equivalent Cu(1) and six equivalent Al(1) atoms. All Ba(5)-Cu(1) bond lengths are 3.27 Å. All Ba(5)-Al(1) bond lengths are 3.42 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 10-coordinate geometry to one Ba(2), three equivalent Ba(1), three equivalent Ba(5), and three equivalent Al(1) atoms. All Cu(1)-Al(1) bond lengths are 2.67 Å. In the second Cu site, Cu(2) is bonded in a 9-coordinate geometry to three equivalent Ba(2), three equivalent Ba(3), and three equivalent Ba(4) atoms. Al(1) is bonded in a 11-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(4), two equivalent Ba(5), one Cu(1), and four equivalent Al(1) atoms. There are two shorter (2.81 Å) and two longer (2.83 Å) Al(1)-Al(1) bond lengths.