DOE OSTI2020
U3La crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent U sites. In the first U site, U is bonded to eight U and four equivalent La atoms to form distorted ULa4U8 cuboctahedra that share corners with four equivalent LaU12 cuboctahedra, corners with fourteen ULa4U8 cuboctahedra, edges with six equivalent LaU12 cuboctahedra, edges with twelve ULa4U8 cuboctahedra, faces with four equivalent LaU12 cuboctahedra, and faces with sixteen ULa4U8 cuboctahedra. There are a spread of U–U bond distances ranging from 2.86–3.44 Å. There are two shorter (3.16 Å) and two longer (3.40 Å) U–La bond lengths. In the second U site, U is bonded to eight equivalent U and four equivalent La atoms to form distorted ULa4U8 cuboctahedra that share corners with four equivalent LaU12 cuboctahedra, corners with fourteen ULa4U8 cuboctahedra, edges with six equivalent LaU12 cuboctahedra, edges with twelve equivalent ULa4U8 cuboctahedra, faces with four equivalent LaU12 cuboctahedra, and faces with sixteen ULa4U8 cuboctahedra. There are two shorter (3.16 Å) and two longer (3.40 Å) U–La bond lengths. In the third U site, U is bonded to eight equivalent U and four equivalent La atoms to form distorted ULa4U8 cuboctahedra that share corners with four equivalent LaU12 cuboctahedra, corners with fourteen ULa4U8 cuboctahedra, edges with six equivalent LaU12 cuboctahedra, edges with twelve equivalent ULa4U8 cuboctahedra, faces with four equivalent LaU12 cuboctahedra, and faces with sixteen ULa4U8 cuboctahedra. There are two shorter (3.16 Å) and two longer (3.40 Å) U–La bond lengths. La is bonded to twelve U atoms to form LaU12 cuboctahedra that share corners with six equivalent LaU12 cuboctahedra, corners with twelve ULa4U8 cuboctahedra, edges with eighteen ULa4U8 cuboctahedra, faces with eight equivalent LaU12 cuboctahedra, and faces with twelve ULa4U8 cuboctahedra.