Ho3Eu is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to four equivalent Ho(1), four equivalent Ho(2), and four equivalent Eu(1) atoms to form HoEu4Ho8 cuboctahedra that share corners with twelve equivalent Ho(1)Eu4Ho8 cuboctahedra, edges with eight equivalent Ho(1)Eu4Ho8 cuboctahedra, edges with eight equivalent Ho(2)Eu4Ho8 cuboctahedra, edges with eight equivalent Eu(1)Ho12 cuboctahedra, faces with four equivalent Ho(2)Eu4Ho8 cuboctahedra, faces with four equivalent Eu(1)Ho12 cuboctahedra, and faces with ten equivalent Ho(1)Eu4Ho8 cuboctahedra. In the second Ho site, Ho(2) is bonded to eight equivalent Ho(1) and four equivalent Eu(1) atoms to form HoEu4Ho8 cuboctahedra that share corners with four equivalent Ho(2)Eu4Ho8 cuboctahedra, corners with eight equivalent Eu(1)Ho12 cuboctahedra, edges with eight equivalent Ho(2)Eu4Ho8 cuboctahedra, edges with sixteen equivalent Ho(1)Eu4Ho8 cuboctahedra, faces with four equivalent Ho(2)Eu4Ho8 cuboctahedra, faces with six equivalent Eu(1)Ho12 cuboctahedra, and faces with eight equivalent Ho(1)Eu4Ho8 cuboctahedra. Eu(1) is bonded to four equivalent Ho(2) and eight equivalent Ho(1) atoms to form EuHo12 cuboctahedra that share corners with four equivalent Eu(1)Ho12 cuboctahedra, corners with eight equivalent Ho(2)Eu4Ho8 cuboctahedra, edges with eight equivalent Eu(1)Ho12 cuboctahedra, edges with sixteen equivalent Ho(1)Eu4Ho8 cuboctahedra, faces with four equivalent Eu(1)Ho12 cuboctahedra, faces with six equivalent Ho(2)Eu4Ho8 cuboctahedra, and faces with eight equivalent Ho(1)Eu4Ho8 cuboctahedra.
Ho3Eu is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ho sites. In the first Ho site, Ho(1) is bonded to four equivalent Ho(1), four equivalent Ho(2), and four equivalent Eu(1) atoms to form HoEu4Ho8 cuboctahedra that share corners with twelve equivalent Ho(1)Eu4Ho8 cuboctahedra, edges with eight equivalent Ho(1)Eu4Ho8 cuboctahedra, edges with eight equivalent Ho(2)Eu4Ho8 cuboctahedra, edges with eight equivalent Eu(1)Ho12 cuboctahedra, faces with four equivalent Ho(2)Eu4Ho8 cuboctahedra, faces with four equivalent Eu(1)Ho12 cuboctahedra, and faces with ten equivalent Ho(1)Eu4Ho8 cuboctahedra. All Ho(1)-Ho(1) bond lengths are 3.45 Å. All Ho(1)-Ho(2) bond lengths are 3.45 Å. All Ho(1)-Eu(1) bond lengths are 3.45 Å. In the second Ho site, Ho(2) is bonded to eight equivalent Ho(1) and four equivalent Eu(1) atoms to form HoEu4Ho8 cuboctahedra that share corners with four equivalent Ho(2)Eu4Ho8 cuboctahedra, corners with eight equivalent Eu(1)Ho12 cuboctahedra, edges with eight equivalent Ho(2)Eu4Ho8 cuboctahedra, edges with sixteen equivalent Ho(1)Eu4Ho8 cuboctahedra, faces with four equivalent Ho(2)Eu4Ho8 cuboctahedra, faces with six equivalent Eu(1)Ho12 cuboctahedra, and faces with eight equivalent Ho(1)Eu4Ho8 cuboctahedra. All Ho(2)-Eu(1) bond lengths are 3.45 Å. Eu(1) is bonded to four equivalent Ho(2) and eight equivalent Ho(1) atoms to form EuHo12 cuboctahedra that share corners with four equivalent Eu(1)Ho12 cuboctahedra, corners with eight equivalent Ho(2)Eu4Ho8 cuboctahedra, edges with eight equivalent Eu(1)Ho12 cuboctahedra, edges with sixteen equivalent Ho(1)Eu4Ho8 cuboctahedra, faces with four equivalent Eu(1)Ho12 cuboctahedra, faces with six equivalent Ho(2)Eu4Ho8 cuboctahedra, and faces with eight equivalent Ho(1)Eu4Ho8 cuboctahedra.