DOE OSTI2020
Tm3Pm is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Tm sites. In the first Tm site, Tm is bonded to eight Tm and four equivalent Pm atoms to form TmPm4Tm8 cuboctahedra that share corners with twelve equivalent TmPm4Tm8 cuboctahedra, edges with eight equivalent PmTm12 cuboctahedra, edges with sixteen TmPm4Tm8 cuboctahedra, faces with four equivalent PmTm12 cuboctahedra, and faces with fourteen TmPm4Tm8 cuboctahedra. There are four shorter (3.53 Å) and four longer (3.54 Å) Tm–Tm bond lengths. All Tm–Pm bond lengths are 3.54 Å. In the second Tm site, Tm is bonded to eight equivalent Tm and four equivalent Pm atoms to form TmPm4Tm8 cuboctahedra that share corners with four equivalent TmPm4Tm8 cuboctahedra, corners with eight equivalent PmTm12 cuboctahedra, edges with twenty-four TmPm4Tm8 cuboctahedra, faces with six equivalent PmTm12 cuboctahedra, and faces with twelve TmPm4Tm8 cuboctahedra. All Tm–Pm bond lengths are 3.53 Å. Pm is bonded to twelve Tm atoms to form PmTm12 cuboctahedra that share corners with four equivalent PmTm12 cuboctahedra, corners with eight equivalent TmPm4Tm8 cuboctahedra, edges with eight equivalent PmTm12 cuboctahedra, edges with sixteen equivalent TmPm4Tm8 cuboctahedra, faces with four equivalent PmTm12 cuboctahedra, and faces with fourteen TmPm4Tm8 cuboctahedra.