ErEu is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. Er(1) is bonded to six equivalent Er(1) and six equivalent Eu(1) atoms to form ErEu6Er6 cuboctahedra that share corners with eighteen equivalent Er(1)Eu6Er6 cuboctahedra, edges with six equivalent Er(1)Eu6Er6 cuboctahedra, edges with twelve equivalent Eu(1)Eu6Er6 cuboctahedra, faces with eight equivalent Er(1)Eu6Er6 cuboctahedra, and faces with twelve equivalent Eu(1)Eu6Er6 cuboctahedra. Eu(1) is bonded to six equivalent Er(1) and six equivalent Eu(1) atoms to form EuEu6Er6 cuboctahedra that share corners with eighteen equivalent Eu(1)Eu6Er6 cuboctahedra, edges with six equivalent Eu(1)Eu6Er6 cuboctahedra, edges with twelve equivalent Er(1)Eu6Er6 cuboctahedra, faces with eight equivalent Eu(1)Eu6Er6 cuboctahedra, and faces with twelve equivalent Er(1)Eu6Er6 cuboctahedra.
ErEu is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. Er(1) is bonded to six equivalent Er(1) and six equivalent Eu(1) atoms to form ErEu6Er6 cuboctahedra that share corners with eighteen equivalent Er(1)Eu6Er6 cuboctahedra, edges with six equivalent Er(1)Eu6Er6 cuboctahedra, edges with twelve equivalent Eu(1)Eu6Er6 cuboctahedra, faces with eight equivalent Er(1)Eu6Er6 cuboctahedra, and faces with twelve equivalent Eu(1)Eu6Er6 cuboctahedra. All Er(1)-Er(1) bond lengths are 3.66 Å. All Er(1)-Eu(1) bond lengths are 3.69 Å. Eu(1) is bonded to six equivalent Er(1) and six equivalent Eu(1) atoms to form EuEu6Er6 cuboctahedra that share corners with eighteen equivalent Eu(1)Eu6Er6 cuboctahedra, edges with six equivalent Eu(1)Eu6Er6 cuboctahedra, edges with twelve equivalent Er(1)Eu6Er6 cuboctahedra, faces with eight equivalent Eu(1)Eu6Er6 cuboctahedra, and faces with twelve equivalent Er(1)Eu6Er6 cuboctahedra. All Eu(1)-Eu(1) bond lengths are 3.66 Å.