DOE OSTI2020
Rb3Tb is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Rb sites. In the first Rb site, Rb is bonded to eight Rb and four equivalent Tb atoms to form RbRb8Tb4 cuboctahedra that share corners with twelve equivalent RbRb8Tb4 cuboctahedra, edges with eight equivalent TbRb12 cuboctahedra, edges with sixteen RbRb8Tb4 cuboctahedra, faces with four equivalent TbRb12 cuboctahedra, and faces with fourteen RbRb8Tb4 cuboctahedra. There are four shorter (4.41 Å) and four longer (4.62 Å) Rb–Rb bond lengths. All Rb–Tb bond lengths are 4.62 Å. In the second Rb site, Rb is bonded to eight equivalent Rb and four equivalent Tb atoms to form distorted RbRb8Tb4 cuboctahedra that share corners with four equivalent RbRb8Tb4 cuboctahedra, corners with eight equivalent TbRb12 cuboctahedra, edges with twenty-four RbRb8Tb4 cuboctahedra, faces with six equivalent TbRb12 cuboctahedra, and faces with twelve RbRb8Tb4 cuboctahedra. All Rb–Tb bond lengths are 4.41 Å. Tb is bonded to twelve Rb atoms to form TbRb12 cuboctahedra that share corners with four equivalent TbRb12 cuboctahedra, corners with eight equivalent RbRb8Tb4 cuboctahedra, edges with eight equivalent TbRb12 cuboctahedra, edges with sixteen equivalent RbRb8Tb4 cuboctahedra, faces with four equivalent TbRb12 cuboctahedra, and faces with fourteen RbRb8Tb4 cuboctahedra.