CaEu3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded to four equivalent Eu(2) and eight equivalent Eu(1) atoms to form CaEu12 cuboctahedra that share corners with four equivalent Ca(1)Eu12 cuboctahedra, corners with eight equivalent Eu(2)Ca4Eu8 cuboctahedra, edges with eight equivalent Ca(1)Eu12 cuboctahedra, edges with sixteen equivalent Eu(1)Ca4Eu8 cuboctahedra, faces with four equivalent Ca(1)Eu12 cuboctahedra, faces with six equivalent Eu(2)Ca4Eu8 cuboctahedra, and faces with eight equivalent Eu(1)Ca4Eu8 cuboctahedra. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to four equivalent Ca(1), four equivalent Eu(1), and four equivalent Eu(2) atoms to form EuCa4Eu8 cuboctahedra that share corners with twelve equivalent Eu(1)Ca4Eu8 cuboctahedra, edges with eight equivalent Ca(1)Eu12 cuboctahedra, edges with eight equivalent Eu(1)Ca4Eu8 cuboctahedra, edges with eight equivalent Eu(2)Ca4Eu8 cuboctahedra, faces with four equivalent Ca(1)Eu12 cuboctahedra, faces with four equivalent Eu(2)Ca4Eu8 cuboctahedra, and faces with ten equivalent Eu(1)Ca4Eu8 cuboctahedra. In the second Eu site, Eu(2) is bonded to four equivalent Ca(1) and eight equivalent Eu(1) atoms to form EuCa4Eu8 cuboctahedra that share corners with four equivalent Eu(2)Ca4Eu8 cuboctahedra, corners with eight equivalent Ca(1)Eu12 cuboctahedra, edges with eight equivalent Eu(2)Ca4Eu8 cuboctahedra, edges with sixteen equivalent Eu(1)Ca4Eu8 cuboctahedra, faces with four equivalent Eu(2)Ca4Eu8 cuboctahedra, faces with six equivalent Ca(1)Eu12 cuboctahedra, and faces with eight equivalent Eu(1)Ca4Eu8 cuboctahedra.
CaEu3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded to four equivalent Eu(2) and eight equivalent Eu(1) atoms to form CaEu12 cuboctahedra that share corners with four equivalent Ca(1)Eu12 cuboctahedra, corners with eight equivalent Eu(2)Ca4Eu8 cuboctahedra, edges with eight equivalent Ca(1)Eu12 cuboctahedra, edges with sixteen equivalent Eu(1)Ca4Eu8 cuboctahedra, faces with four equivalent Ca(1)Eu12 cuboctahedra, faces with six equivalent Eu(2)Ca4Eu8 cuboctahedra, and faces with eight equivalent Eu(1)Ca4Eu8 cuboctahedra. All Ca(1)-Eu(2) bond lengths are 3.93 Å. All Ca(1)-Eu(1) bond lengths are 3.98 Å. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to four equivalent Ca(1), four equivalent Eu(1), and four equivalent Eu(2) atoms to form EuCa4Eu8 cuboctahedra that share corners with twelve equivalent Eu(1)Ca4Eu8 cuboctahedra, edges with eight equivalent Ca(1)Eu12 cuboctahedra, edges with eight equivalent Eu(1)Ca4Eu8 cuboctahedra, edges with eight equivalent Eu(2)Ca4Eu8 cuboctahedra, faces with four equivalent Ca(1)Eu12 cuboctahedra, faces with four equivalent Eu(2)Ca4Eu8 cuboctahedra, and faces with ten equivalent Eu(1)Ca4Eu8 cuboctahedra. All Eu(1)-Eu(1) bond lengths are 3.93 Å. All Eu(1)-Eu(2) bond lengths are 3.98 Å. In the second Eu site, Eu(2) is bonded to four equivalent Ca(1) and eight equivalent Eu(1) atoms to form EuCa4Eu8 cuboctahedra that share corners with four equivalent Eu(2)Ca4Eu8 cuboctahedra, corners with eight equivalent Ca(1)Eu12 cuboctahedra, edges with eight equivalent Eu(2)Ca4Eu8 cuboctahedra, edges with sixteen equivalent Eu(1)Ca4Eu8 cuboctahedra, faces with four equivalent Eu(2)Ca4Eu8 cuboctahedra, faces with six equivalent Ca(1)Eu12 cuboctahedra, and faces with eight equivalent Eu(1)Ca4Eu8 cuboctahedra.