Er3Ce is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to four equivalent Er(1), four equivalent Er(2), and four equivalent Ce(1) atoms to form ErCe4Er8 cuboctahedra that share corners with twelve equivalent Er(1)Ce4Er8 cuboctahedra, edges with eight equivalent Er(1)Ce4Er8 cuboctahedra, edges with eight equivalent Er(2)Ce4Er8 cuboctahedra, edges with eight equivalent Ce(1)Er12 cuboctahedra, faces with four equivalent Er(2)Ce4Er8 cuboctahedra, faces with four equivalent Ce(1)Er12 cuboctahedra, and faces with ten equivalent Er(1)Ce4Er8 cuboctahedra. In the second Er site, Er(2) is bonded to eight equivalent Er(1) and four equivalent Ce(1) atoms to form ErCe4Er8 cuboctahedra that share corners with four equivalent Er(2)Ce4Er8 cuboctahedra, corners with eight equivalent Ce(1)Er12 cuboctahedra, edges with eight equivalent Er(2)Ce4Er8 cuboctahedra, edges with sixteen equivalent Er(1)Ce4Er8 cuboctahedra, faces with four equivalent Er(2)Ce4Er8 cuboctahedra, faces with six equivalent Ce(1)Er12 cuboctahedra, and faces with eight equivalent Er(1)Ce4Er8 cuboctahedra. Ce(1) is bonded to four equivalent Er(2) and eight equivalent Er(1) atoms to form CeEr12 cuboctahedra that share corners with four equivalent Ce(1)Er12 cuboctahedra, corners with eight equivalent Er(2)Ce4Er8 cuboctahedra, edges with eight equivalent Ce(1)Er12 cuboctahedra, edges with sixteen equivalent Er(1)Ce4Er8 cuboctahedra, faces with four equivalent Ce(1)Er12 cuboctahedra, faces with six equivalent Er(2)Ce4Er8 cuboctahedra, and faces with eight equivalent Er(1)Ce4Er8 cuboctahedra.
Er3Ce is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to four equivalent Er(1), four equivalent Er(2), and four equivalent Ce(1) atoms to form ErCe4Er8 cuboctahedra that share corners with twelve equivalent Er(1)Ce4Er8 cuboctahedra, edges with eight equivalent Er(1)Ce4Er8 cuboctahedra, edges with eight equivalent Er(2)Ce4Er8 cuboctahedra, edges with eight equivalent Ce(1)Er12 cuboctahedra, faces with four equivalent Er(2)Ce4Er8 cuboctahedra, faces with four equivalent Ce(1)Er12 cuboctahedra, and faces with ten equivalent Er(1)Ce4Er8 cuboctahedra. All Er(1)-Er(1) bond lengths are 3.53 Å. All Er(1)-Er(2) bond lengths are 3.52 Å. All Er(1)-Ce(1) bond lengths are 3.52 Å. In the second Er site, Er(2) is bonded to eight equivalent Er(1) and four equivalent Ce(1) atoms to form ErCe4Er8 cuboctahedra that share corners with four equivalent Er(2)Ce4Er8 cuboctahedra, corners with eight equivalent Ce(1)Er12 cuboctahedra, edges with eight equivalent Er(2)Ce4Er8 cuboctahedra, edges with sixteen equivalent Er(1)Ce4Er8 cuboctahedra, faces with four equivalent Er(2)Ce4Er8 cuboctahedra, faces with six equivalent Ce(1)Er12 cuboctahedra, and faces with eight equivalent Er(1)Ce4Er8 cuboctahedra. All Er(2)-Ce(1) bond lengths are 3.53 Å. Ce(1) is bonded to four equivalent Er(2) and eight equivalent Er(1) atoms to form CeEr12 cuboctahedra that share corners with four equivalent Ce(1)Er12 cuboctahedra, corners with eight equivalent Er(2)Ce4Er8 cuboctahedra, edges with eight equivalent Ce(1)Er12 cuboctahedra, edges with sixteen equivalent Er(1)Ce4Er8 cuboctahedra, faces with four equivalent Ce(1)Er12 cuboctahedra, faces with six equivalent Er(2)Ce4Er8 cuboctahedra, and faces with eight equivalent Er(1)Ce4Er8 cuboctahedra.