DOE OSTI2020
TmBi3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm is bonded to twelve Bi atoms to form TmBi12 cuboctahedra that share corners with four equivalent TmBi12 cuboctahedra, edges with eight equivalent TmBi12 cuboctahedra, edges with sixteen equivalent BiTm4Bi8 cuboctahedra, faces with four equivalent TmBi12 cuboctahedra, and faces with eight equivalent BiTm4Bi8 cuboctahedra. There are four shorter (3.31 Å) and eight longer (3.61 Å) Tm–Bi bond lengths. There are two inequivalent Bi sites. In the first Bi site, Bi is bonded to four equivalent Tm and eight Bi atoms to form distorted BiTm4Bi8 cuboctahedra that share corners with twelve equivalent BiTm4Bi8 cuboctahedra, edges with eight equivalent TmBi12 cuboctahedra, edges with eight equivalent BiTm4Bi8 cuboctahedra, faces with four equivalent TmBi12 cuboctahedra, and faces with ten equivalent BiTm4Bi8 cuboctahedra. There are four shorter (3.31 Å) and four longer (3.61 Å) Bi–Bi bond lengths. In the second Bi site, Bi is bonded in a square co-planar geometry to four equivalent Tm and eight equivalent Bi atoms.