DOE OSTI2020
Tm5Ni2Sb crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent Tm sites. In the first Tm site, Tm is bonded to four equivalent Ni and two equivalent Sb atoms to form distorted TmNi4Sb2 octahedra that share corners with six equivalent TmNi4Sb2 octahedra, corners with sixteen equivalent TmNi3Sb2 trigonal bipyramids, and faces with eight equivalent TmNi3Sb2 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 0–51°. All Tm–Ni bond lengths are 2.91 Å. Both Tm–Sb bond lengths are 3.36 Å. In the second Tm site, Tm is bonded to three equivalent Ni and two equivalent Sb atoms to form distorted TmNi3Sb2 trigonal bipyramids that share corners with four equivalent TmNi4Sb2 octahedra, corners with twelve equivalent TmNi3Sb2 trigonal bipyramids, edges with seven equivalent TmNi3Sb2 trigonal bipyramids, faces with two equivalent TmNi4Sb2 octahedra, and a faceface with one TmNi3Sb2 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 42–61°. There are two shorter (2.83 Å) and one longer (2.88 Å) Tm–Ni bond lengths. Both Tm–Sb bond lengths are 3.19 Å. Ni is bonded in a 9-coordinate geometry to eight Tm and one Ni atom. The Ni–Ni bond length is 2.76 Å. Sb is bonded in a 10-coordinate geometry to ten Tm atoms.