Ca3Eu is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Ca(1) is bonded to eight equivalent Ca(1) and four equivalent Eu(1) atoms to form CaCa8Eu4 cuboctahedra that share corners with four equivalent Eu(1)Ca12 cuboctahedra, corners with fourteen equivalent Ca(1)Ca8Eu4 cuboctahedra, edges with six equivalent Eu(1)Ca12 cuboctahedra, edges with twelve equivalent Ca(1)Ca8Eu4 cuboctahedra, faces with four equivalent Eu(1)Ca12 cuboctahedra, and faces with sixteen equivalent Ca(1)Ca8Eu4 cuboctahedra. Eu(1) is bonded to twelve equivalent Ca(1) atoms to form EuCa12 cuboctahedra that share corners with six equivalent Eu(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(1)Ca8Eu4 cuboctahedra, edges with eighteen equivalent Ca(1)Ca8Eu4 cuboctahedra, faces with eight equivalent Eu(1)Ca12 cuboctahedra, and faces with twelve equivalent Ca(1)Ca8Eu4 cuboctahedra.
Ca3Eu is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Ca(1) is bonded to eight equivalent Ca(1) and four equivalent Eu(1) atoms to form CaCa8Eu4 cuboctahedra that share corners with four equivalent Eu(1)Ca12 cuboctahedra, corners with fourteen equivalent Ca(1)Ca8Eu4 cuboctahedra, edges with six equivalent Eu(1)Ca12 cuboctahedra, edges with twelve equivalent Ca(1)Ca8Eu4 cuboctahedra, faces with four equivalent Eu(1)Ca12 cuboctahedra, and faces with sixteen equivalent Ca(1)Ca8Eu4 cuboctahedra. There are a spread of Ca(1)-Ca(1) bond distances ranging from 3.96-3.99 Å. There are two shorter (3.96 Å) and two longer (3.99 Å) Ca(1)-Eu(1) bond lengths. Eu(1) is bonded to twelve equivalent Ca(1) atoms to form EuCa12 cuboctahedra that share corners with six equivalent Eu(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(1)Ca8Eu4 cuboctahedra, edges with eighteen equivalent Ca(1)Ca8Eu4 cuboctahedra, faces with eight equivalent Eu(1)Ca12 cuboctahedra, and faces with twelve equivalent Ca(1)Ca8Eu4 cuboctahedra.