DOE OSTI2020
Tm8CoGa3 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are four inequivalent Tm sites. In the first Tm site, Tm is bonded to one Co and four equivalent Ga atoms to form distorted TmGa4Co trigonal pyramids that share corners with two equivalent TmGa6 octahedra, corners with three equivalent TmGa3Co tetrahedra, corners with six equivalent TmGa4Co trigonal pyramids, an edgeedge with one TmGa3Co tetrahedra, edges with four equivalent TmGa4Co trigonal pyramids, and faces with two equivalent TmGa6 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. The Tm–Co bond length is 2.78 Å. There are a spread of Tm–Ga bond distances ranging from 2.90–3.76 Å. In the second Tm site, Tm is bonded to one Co and three equivalent Ga atoms to form distorted TmGa3Co tetrahedra that share corners with six equivalent TmGa6 octahedra, corners with nine equivalent TmGa4Co trigonal pyramids, and edges with three equivalent TmGa4Co trigonal pyramids. The corner-sharing octahedra tilt angles range from 16–47°. The Tm–Co bond length is 2.64 Å. All Tm–Ga bond lengths are 3.04 Å. In the third Tm site, Tm is bonded in a 3-coordinate geometry to one Co and four equivalent Ga atoms. The Tm–Co bond length is 2.75 Å. There are two shorter (3.13 Å) and two longer (3.65 Å) Tm–Ga bond lengths. In the fourth Tm site, Tm is bonded to six equivalent Ga atoms to form distorted TmGa6 octahedra that share corners with six equivalent TmGa3Co tetrahedra, corners with six equivalent TmGa4Co trigonal pyramids, faces with two equivalent TmGa6 octahedra, and faces with six equivalent TmGa4Co trigonal pyramids. There are three shorter (3.20 Å) and three longer (3.35 Å) Tm–Ga bond lengths. Co is bonded in a 7-coordinate geometry to seven Tm atoms. Ga is bonded in a 11-coordinate geometry to eleven Tm atoms.