Dy2Fe15Al2 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 18-coordinate geometry to six equivalent Fe(2) and twelve equivalent Fe(3) atoms. In the second Dy site, Dy(2) is bonded in a 20-coordinate geometry to six equivalent Fe(1), six equivalent Fe(2), six equivalent Fe(3), and two equivalent Al(1) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Dy(2), four equivalent Fe(2), four equivalent Fe(3), and two equivalent Al(1) atoms to form distorted FeDy2Al2Fe8 cuboctahedra that share corners with four equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, corners with eight equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Dy3AlFe8 cuboctahedra, edges with four equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, edges with six equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with four equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with six equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, and faces with eight equivalent Fe(2)Dy2Al2Fe8 cuboctahedra. In the second Fe site, Fe(2) is bonded to one Dy(1), one Dy(2), two equivalent Fe(1), two equivalent Fe(2), four equivalent Fe(3), and two equivalent Al(1) atoms to form distorted FeDy2Al2Fe8 cuboctahedra that share corners with four equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, corners with eight equivalent Fe(3)Dy3AlFe8 cuboctahedra, corners with twelve equivalent Fe(2)Dy2Al2Fe8 cuboctahedra,  an edgeedge with one Fe(2)Dy2Al2Fe8 cuboctahedra, edges with two equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, edges with two equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with four equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, faces with seven equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, and faces with ten equivalent Fe(3)Dy3AlFe8 cuboctahedra. In the third Fe site, Fe(3) is bonded to one Dy(2), two equivalent Dy(1), two equivalent Fe(1), two equivalent Fe(3), four equivalent Fe(2), and one Al(1) atom to form distorted FeDy3AlFe8 cuboctahedra that share corners with five equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, corners with eight equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Dy3AlFe8 cuboctahedra, edges with two equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, edges with three equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, edges with five equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with two equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, faces with eight equivalent Fe(3)Dy3AlFe8 cuboctahedra, and faces with ten equivalent Fe(2)Dy2Al2Fe8 cuboctahedra. Al(1) is bonded in a 14-coordinate geometry to one Dy(2), three equivalent Fe(1), three equivalent Fe(3), six equivalent Fe(2), and one Al(1) atom.
Dy2Fe15Al2 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 18-coordinate geometry to six equivalent Fe(2) and twelve equivalent Fe(3) atoms. All Dy(1)-Fe(2) bond lengths are 2.92 Å. There are six shorter (3.14 Å) and six longer (3.24 Å) Dy(1)-Fe(3) bond lengths. In the second Dy site, Dy(2) is bonded in a 20-coordinate geometry to six equivalent Fe(1), six equivalent Fe(2), six equivalent Fe(3), and two equivalent Al(1) atoms. All Dy(2)-Fe(1) bond lengths are 3.20 Å. All Dy(2)-Fe(2) bond lengths are 2.94 Å. All Dy(2)-Fe(3) bond lengths are 3.16 Å. Both Dy(2)-Al(1) bond lengths are 2.95 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Dy(2), four equivalent Fe(2), four equivalent Fe(3), and two equivalent Al(1) atoms to form distorted FeDy2Al2Fe8 cuboctahedra that share corners with four equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, corners with eight equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Dy3AlFe8 cuboctahedra, edges with four equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, edges with six equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with four equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with six equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, and faces with eight equivalent Fe(2)Dy2Al2Fe8 cuboctahedra. All Fe(1)-Fe(2) bond lengths are 2.47 Å. All Fe(1)-Fe(3) bond lengths are 2.43 Å. Both Fe(1)-Al(1) bond lengths are 2.56 Å. In the second Fe site, Fe(2) is bonded to one Dy(1), one Dy(2), two equivalent Fe(1), two equivalent Fe(2), four equivalent Fe(3), and two equivalent Al(1) atoms to form distorted FeDy2Al2Fe8 cuboctahedra that share corners with four equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, corners with eight equivalent Fe(3)Dy3AlFe8 cuboctahedra, corners with twelve equivalent Fe(2)Dy2Al2Fe8 cuboctahedra,  an edgeedge with one Fe(2)Dy2Al2Fe8 cuboctahedra, edges with two equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, edges with two equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with four equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, faces with seven equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, and faces with ten equivalent Fe(3)Dy3AlFe8 cuboctahedra. There is one shorter (2.51 Å) and one longer (2.56 Å) Fe(2)-Fe(2) bond length. There are two shorter (2.53 Å) and two longer (2.61 Å) Fe(2)-Fe(3) bond lengths. Both Fe(2)-Al(1) bond lengths are 2.82 Å. In the third Fe site, Fe(3) is bonded to one Dy(2), two equivalent Dy(1), two equivalent Fe(1), two equivalent Fe(3), four equivalent Fe(2), and one Al(1) atom to form distorted FeDy3AlFe8 cuboctahedra that share corners with five equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, corners with eight equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, corners with ten equivalent Fe(3)Dy3AlFe8 cuboctahedra, edges with two equivalent Fe(2)Dy2Al2Fe8 cuboctahedra, edges with three equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, edges with five equivalent Fe(3)Dy3AlFe8 cuboctahedra, faces with two equivalent Fe(1)Dy2Al2Fe8 cuboctahedra, faces with eight equivalent Fe(3)Dy3AlFe8 cuboctahedra, and faces with ten equivalent Fe(2)Dy2Al2Fe8 cuboctahedra. Both Fe(3)-Fe(3) bond lengths are 2.41 Å. The Fe(3)-Al(1) bond length is 2.61 Å. Al(1) is bonded in a 14-coordinate geometry to one Dy(2), three equivalent Fe(1), three equivalent Fe(3), six equivalent Fe(2), and one Al(1) atom. The Al(1)-Al(1) bond length is 2.51 Å.