Ho4HfAl15 is Uranium Silicide-derived structured and crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to four equivalent Al(2), four equivalent Al(4), and four equivalent Al(5) atoms to form HoAl12 cuboctahedra that share corners with four equivalent Ho(1)Al12 cuboctahedra, corners with four equivalent Ho(2)Al12 cuboctahedra, corners with four equivalent Hf(1)Al12 cuboctahedra, edges with four equivalent Al(1)Hf4Al8 cuboctahedra, edges with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra,  a faceface with one Ho(2)Al12 cuboctahedra,  a faceface with one Hf(1)Al12 cuboctahedra, faces with four equivalent Ho(1)Al12 cuboctahedra, faces with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with four equivalent Al(2)Ho4Al8 cuboctahedra, and faces with four equivalent Al(5)Ho4Al8 cuboctahedra. In the second Ho site, Ho(2) is bonded to four equivalent Al(3), four equivalent Al(5), and four equivalent Al(6) atoms to form HoAl12 cuboctahedra that share corners with four equivalent Ho(1)Al12 cuboctahedra, corners with eight equivalent Ho(2)Al12 cuboctahedra, edges with four equivalent Al(2)Ho4Al8 cuboctahedra, edges with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra, edges with eight equivalent Al(6)Ho4Al8 cuboctahedra,  a faceface with one Ho(1)Al12 cuboctahedra, faces with four equivalent Al(3)Ho4Al8 cuboctahedra, faces with four equivalent Al(5)Ho4Al8 cuboctahedra, faces with four equivalent Al(6)Ho4Al8 cuboctahedra, and faces with five equivalent Ho(2)Al12 cuboctahedra. Hf(1) is bonded to four equivalent Al(1) and eight equivalent Al(4) atoms to form HfAl12 cuboctahedra that share corners with four equivalent Hf(1)Al12 cuboctahedra, corners with eight equivalent Ho(1)Al12 cuboctahedra, edges with eight equivalent Al(2)Ho4Al8 cuboctahedra, edges with sixteen equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, faces with four equivalent Al(1)Hf4Al8 cuboctahedra, and faces with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra. There are six inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Hf(1) and eight equivalent Al(4) atoms to form AlHf4Al8 cuboctahedra that share corners with four equivalent Al(1)Hf4Al8 cuboctahedra, corners with eight equivalent Al(2)Ho4Al8 cuboctahedra, edges with eight equivalent Ho(1)Al12 cuboctahedra, edges with sixteen equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with two equivalent Al(2)Ho4Al8 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, faces with four equivalent Al(1)Hf4Al8 cuboctahedra, and faces with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra. In the second Al site, Al(2) is bonded to four equivalent Ho(1), four equivalent Al(4), and four equivalent Al(5) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(1)Hf4Al8 cuboctahedra, corners with four equivalent Al(2)Ho4Al8 cuboctahedra, corners with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with four equivalent Ho(2)Al12 cuboctahedra, edges with four equivalent Hf(1)Al12 cuboctahedra, edges with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra,  a faceface with one Al(1)Hf4Al8 cuboctahedra,  a faceface with one Al(3)Ho4Al8 cuboctahedra, faces with four equivalent Ho(1)Al12 cuboctahedra, faces with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with four equivalent Al(2)Ho4Al8 cuboctahedra, and faces with four equivalent Al(5)Ho4Al8 cuboctahedra. In the third Al site, Al(3) is bonded to four equivalent Ho(2), four equivalent Al(5), and four equivalent Al(6) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(2)Ho4Al8 cuboctahedra, corners with eight equivalent Al(3)Ho4Al8 cuboctahedra, edges with four equivalent Ho(1)Al12 cuboctahedra, edges with four equivalent Ho(2)Al12 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra, edges with eight equivalent Al(6)Ho4Al8 cuboctahedra,  a faceface with one Al(2)Ho4Al8 cuboctahedra, faces with four equivalent Ho(2)Al12 cuboctahedra, faces with four equivalent Al(5)Ho4Al8 cuboctahedra, faces with four equivalent Al(6)Ho4Al8 cuboctahedra, and faces with five equivalent Al(3)Ho4Al8 cuboctahedra. In the fourth Al site, Al(4) is bonded to two equivalent Ho(1), two equivalent Hf(1), two equivalent Al(1), two equivalent Al(2), and four equivalent Al(4) atoms to form distorted AlHo2Hf2Al8 cuboctahedra that share corners with four equivalent Al(5)Ho4Al8 cuboctahedra, corners with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with four equivalent Ho(1)Al12 cuboctahedra, edges with four equivalent Hf(1)Al12 cuboctahedra, edges with four equivalent Al(1)Hf4Al8 cuboctahedra, edges with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with four equivalent Al(2)Ho4Al8 cuboctahedra, edges with four equivalent Al(5)Ho4Al8 cuboctahedra,  a faceface with one Al(5)Ho4Al8 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, faces with two equivalent Hf(1)Al12 cuboctahedra, faces with two equivalent Al(1)Hf4Al8 cuboctahedra, faces with two equivalent Al(2)Ho4Al8 cuboctahedra, and faces with nine equivalent Al(4)Ho2Hf2Al8 cuboctahedra. In the fifth Al site, Al(5) is bonded to two equivalent Ho(1), two equivalent Ho(2), two equivalent Al(2), two equivalent Al(3), and four equivalent Al(5) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, corners with four equivalent Al(5)Ho4Al8 cuboctahedra, corners with four equivalent Al(6)Ho4Al8 cuboctahedra, edges with four equivalent Ho(1)Al12 cuboctahedra, edges with four equivalent Ho(2)Al12 cuboctahedra, edges with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with four equivalent Al(2)Ho4Al8 cuboctahedra, edges with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with four equivalent Al(6)Ho4Al8 cuboctahedra,  a faceface with one Al(4)Ho2Hf2Al8 cuboctahedra,  a faceface with one Al(6)Ho4Al8 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, faces with two equivalent Ho(2)Al12 cuboctahedra, faces with two equivalent Al(2)Ho4Al8 cuboctahedra, faces with two equivalent Al(3)Ho4Al8 cuboctahedra, and faces with eight equivalent Al(5)Ho4Al8 cuboctahedra. In the sixth Al site, Al(6) is bonded to four equivalent Ho(2), four equivalent Al(3), and four equivalent Al(6) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(6)Ho4Al8 cuboctahedra, corners with eight equivalent Al(5)Ho4Al8 cuboctahedra, edges with eight equivalent Ho(2)Al12 cuboctahedra, edges with eight equivalent Al(3)Ho4Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra, faces with two equivalent Al(5)Ho4Al8 cuboctahedra, faces with four equivalent Ho(2)Al12 cuboctahedra, faces with four equivalent Al(3)Ho4Al8 cuboctahedra, and faces with eight equivalent Al(6)Ho4Al8 cuboctahedra.
Ho4HfAl15 is Uranium Silicide-derived structured and crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to four equivalent Al(2), four equivalent Al(4), and four equivalent Al(5) atoms to form HoAl12 cuboctahedra that share corners with four equivalent Ho(1)Al12 cuboctahedra, corners with four equivalent Ho(2)Al12 cuboctahedra, corners with four equivalent Hf(1)Al12 cuboctahedra, edges with four equivalent Al(1)Hf4Al8 cuboctahedra, edges with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra,  a faceface with one Ho(2)Al12 cuboctahedra,  a faceface with one Hf(1)Al12 cuboctahedra, faces with four equivalent Ho(1)Al12 cuboctahedra, faces with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with four equivalent Al(2)Ho4Al8 cuboctahedra, and faces with four equivalent Al(5)Ho4Al8 cuboctahedra. All Ho(1)-Al(2) bond lengths are 2.98 Å. All Ho(1)-Al(4) bond lengths are 3.00 Å. All Ho(1)-Al(5) bond lengths are 3.01 Å. In the second Ho site, Ho(2) is bonded to four equivalent Al(3), four equivalent Al(5), and four equivalent Al(6) atoms to form HoAl12 cuboctahedra that share corners with four equivalent Ho(1)Al12 cuboctahedra, corners with eight equivalent Ho(2)Al12 cuboctahedra, edges with four equivalent Al(2)Ho4Al8 cuboctahedra, edges with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra, edges with eight equivalent Al(6)Ho4Al8 cuboctahedra,  a faceface with one Ho(1)Al12 cuboctahedra, faces with four equivalent Al(3)Ho4Al8 cuboctahedra, faces with four equivalent Al(5)Ho4Al8 cuboctahedra, faces with four equivalent Al(6)Ho4Al8 cuboctahedra, and faces with five equivalent Ho(2)Al12 cuboctahedra. All Ho(2)-Al(3) bond lengths are 2.98 Å. All Ho(2)-Al(5) bond lengths are 3.00 Å. All Ho(2)-Al(6) bond lengths are 2.99 Å. Hf(1) is bonded to four equivalent Al(1) and eight equivalent Al(4) atoms to form HfAl12 cuboctahedra that share corners with four equivalent Hf(1)Al12 cuboctahedra, corners with eight equivalent Ho(1)Al12 cuboctahedra, edges with eight equivalent Al(2)Ho4Al8 cuboctahedra, edges with sixteen equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, faces with four equivalent Al(1)Hf4Al8 cuboctahedra, and faces with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra. All Hf(1)-Al(1) bond lengths are 2.98 Å. All Hf(1)-Al(4) bond lengths are 2.91 Å. There are six inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Hf(1) and eight equivalent Al(4) atoms to form AlHf4Al8 cuboctahedra that share corners with four equivalent Al(1)Hf4Al8 cuboctahedra, corners with eight equivalent Al(2)Ho4Al8 cuboctahedra, edges with eight equivalent Ho(1)Al12 cuboctahedra, edges with sixteen equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with two equivalent Al(2)Ho4Al8 cuboctahedra, faces with four equivalent Hf(1)Al12 cuboctahedra, faces with four equivalent Al(1)Hf4Al8 cuboctahedra, and faces with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra. All Al(1)-Al(4) bond lengths are 2.91 Å. In the second Al site, Al(2) is bonded to four equivalent Ho(1), four equivalent Al(4), and four equivalent Al(5) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(1)Hf4Al8 cuboctahedra, corners with four equivalent Al(2)Ho4Al8 cuboctahedra, corners with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with four equivalent Ho(2)Al12 cuboctahedra, edges with four equivalent Hf(1)Al12 cuboctahedra, edges with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra,  a faceface with one Al(1)Hf4Al8 cuboctahedra,  a faceface with one Al(3)Ho4Al8 cuboctahedra, faces with four equivalent Ho(1)Al12 cuboctahedra, faces with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, faces with four equivalent Al(2)Ho4Al8 cuboctahedra, and faces with four equivalent Al(5)Ho4Al8 cuboctahedra. All Al(2)-Al(4) bond lengths are 3.02 Å. All Al(2)-Al(5) bond lengths are 2.99 Å. In the third Al site, Al(3) is bonded to four equivalent Ho(2), four equivalent Al(5), and four equivalent Al(6) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(2)Ho4Al8 cuboctahedra, corners with eight equivalent Al(3)Ho4Al8 cuboctahedra, edges with four equivalent Ho(1)Al12 cuboctahedra, edges with four equivalent Ho(2)Al12 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra, edges with eight equivalent Al(6)Ho4Al8 cuboctahedra,  a faceface with one Al(2)Ho4Al8 cuboctahedra, faces with four equivalent Ho(2)Al12 cuboctahedra, faces with four equivalent Al(5)Ho4Al8 cuboctahedra, faces with four equivalent Al(6)Ho4Al8 cuboctahedra, and faces with five equivalent Al(3)Ho4Al8 cuboctahedra. All Al(3)-Al(5) bond lengths are 2.99 Å. All Al(3)-Al(6) bond lengths are 2.99 Å. In the fourth Al site, Al(4) is bonded to two equivalent Ho(1), two equivalent Hf(1), two equivalent Al(1), two equivalent Al(2), and four equivalent Al(4) atoms to form distorted AlHo2Hf2Al8 cuboctahedra that share corners with four equivalent Al(5)Ho4Al8 cuboctahedra, corners with eight equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with four equivalent Ho(1)Al12 cuboctahedra, edges with four equivalent Hf(1)Al12 cuboctahedra, edges with four equivalent Al(1)Hf4Al8 cuboctahedra, edges with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with four equivalent Al(2)Ho4Al8 cuboctahedra, edges with four equivalent Al(5)Ho4Al8 cuboctahedra,  a faceface with one Al(5)Ho4Al8 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, faces with two equivalent Hf(1)Al12 cuboctahedra, faces with two equivalent Al(1)Hf4Al8 cuboctahedra, faces with two equivalent Al(2)Ho4Al8 cuboctahedra, and faces with nine equivalent Al(4)Ho2Hf2Al8 cuboctahedra. All Al(4)-Al(4) bond lengths are 2.98 Å. In the fifth Al site, Al(5) is bonded to two equivalent Ho(1), two equivalent Ho(2), two equivalent Al(2), two equivalent Al(3), and four equivalent Al(5) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, corners with four equivalent Al(5)Ho4Al8 cuboctahedra, corners with four equivalent Al(6)Ho4Al8 cuboctahedra, edges with four equivalent Ho(1)Al12 cuboctahedra, edges with four equivalent Ho(2)Al12 cuboctahedra, edges with four equivalent Al(4)Ho2Hf2Al8 cuboctahedra, edges with four equivalent Al(2)Ho4Al8 cuboctahedra, edges with four equivalent Al(3)Ho4Al8 cuboctahedra, edges with four equivalent Al(6)Ho4Al8 cuboctahedra,  a faceface with one Al(4)Ho2Hf2Al8 cuboctahedra,  a faceface with one Al(6)Ho4Al8 cuboctahedra, faces with two equivalent Ho(1)Al12 cuboctahedra, faces with two equivalent Ho(2)Al12 cuboctahedra, faces with two equivalent Al(2)Ho4Al8 cuboctahedra, faces with two equivalent Al(3)Ho4Al8 cuboctahedra, and faces with eight equivalent Al(5)Ho4Al8 cuboctahedra. All Al(5)-Al(5) bond lengths are 2.98 Å. In the sixth Al site, Al(6) is bonded to four equivalent Ho(2), four equivalent Al(3), and four equivalent Al(6) atoms to form distorted AlHo4Al8 cuboctahedra that share corners with four equivalent Al(6)Ho4Al8 cuboctahedra, corners with eight equivalent Al(5)Ho4Al8 cuboctahedra, edges with eight equivalent Ho(2)Al12 cuboctahedra, edges with eight equivalent Al(3)Ho4Al8 cuboctahedra, edges with eight equivalent Al(5)Ho4Al8 cuboctahedra, faces with two equivalent Al(5)Ho4Al8 cuboctahedra, faces with four equivalent Ho(2)Al12 cuboctahedra, faces with four equivalent Al(3)Ho4Al8 cuboctahedra, and faces with eight equivalent Al(6)Ho4Al8 cuboctahedra. All Al(6)-Al(6) bond lengths are 2.98 Å.