DOE OSTI2020
UYb3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U is bonded to twelve Yb atoms to form UYb12 cuboctahedra that share corners with four equivalent UYb12 cuboctahedra, corners with eight equivalent YbYb8U4 cuboctahedra, edges with eight equivalent UYb12 cuboctahedra, edges with sixteen equivalent YbYb8U4 cuboctahedra, faces with four equivalent UYb12 cuboctahedra, and faces with fourteen YbYb8U4 cuboctahedra. There are four shorter (3.65 Å) and eight longer (3.72 Å) U–Yb bond lengths. There are two inequivalent Yb sites. In the first Yb site, Yb is bonded to four equivalent U and eight Yb atoms to form YbYb8U4 cuboctahedra that share corners with twelve equivalent YbYb8U4 cuboctahedra, edges with eight equivalent UYb12 cuboctahedra, edges with sixteen YbYb8U4 cuboctahedra, faces with four equivalent UYb12 cuboctahedra, and faces with fourteen YbYb8U4 cuboctahedra. There are four shorter (3.65 Å) and four longer (3.72 Å) Yb–Yb bond lengths. In the second Yb site, Yb is bonded to four equivalent U and eight equivalent Yb atoms to form distorted YbYb8U4 cuboctahedra that share corners with four equivalent YbYb8U4 cuboctahedra, corners with eight equivalent UYb12 cuboctahedra, edges with twenty-four YbYb8U4 cuboctahedra, faces with six equivalent UYb12 cuboctahedra, and faces with twelve YbYb8U4 cuboctahedra.