DOE OSTI2020
RbEu3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Rb is bonded to twelve Eu atoms to form RbEu12 cuboctahedra that share corners with four equivalent RbEu12 cuboctahedra, corners with eight equivalent EuRb4Eu8 cuboctahedra, edges with eight equivalent RbEu12 cuboctahedra, edges with sixteen equivalent EuRb4Eu8 cuboctahedra, faces with four equivalent RbEu12 cuboctahedra, and faces with fourteen EuRb4Eu8 cuboctahedra. There are four shorter (4.22 Å) and eight longer (4.25 Å) Rb–Eu bond lengths. There are two inequivalent Eu sites. In the first Eu site, Eu is bonded to four equivalent Rb and eight Eu atoms to form EuRb4Eu8 cuboctahedra that share corners with twelve equivalent EuRb4Eu8 cuboctahedra, edges with eight equivalent RbEu12 cuboctahedra, edges with sixteen EuRb4Eu8 cuboctahedra, faces with four equivalent RbEu12 cuboctahedra, and faces with fourteen EuRb4Eu8 cuboctahedra. There are four shorter (4.22 Å) and four longer (4.25 Å) Eu–Eu bond lengths. In the second Eu site, Eu is bonded to four equivalent Rb and eight equivalent Eu atoms to form distorted EuRb4Eu8 cuboctahedra that share corners with four equivalent EuRb4Eu8 cuboctahedra, corners with eight equivalent RbEu12 cuboctahedra, edges with twenty-four EuRb4Eu8 cuboctahedra, faces with six equivalent RbEu12 cuboctahedra, and faces with twelve EuRb4Eu8 cuboctahedra.