DOE OSTI2020
Ni6SbTe2 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. there are four inequivalent Ni+1.17+ sites. In the first Ni+1.17+ site, Ni+1.17+ is bonded to two equivalent Sb3- and two equivalent Te2- atoms to form distorted NiSb2Te2 tetrahedra that share corners with two equivalent NiTe5 square pyramids, corners with ten NiSb2Te2 tetrahedra, and edges with five NiSb2Te2 tetrahedra. Both Ni–Sb bond lengths are 2.63 Å. Both Ni–Te bond lengths are 2.51 Å. In the second Ni+1.17+ site, Ni+1.17+ is bonded to two equivalent Sb3- and two equivalent Te2- atoms to form distorted NiSb2Te2 tetrahedra that share corners with four equivalent NiTe5 square pyramids, corners with ten NiSb2Te2 tetrahedra, edges with two equivalent NiTe5 square pyramids, and edges with five NiSb2Te2 tetrahedra. Both Ni–Sb bond lengths are 2.61 Å. Both Ni–Te bond lengths are 2.59 Å. In the third Ni+1.17+ site, Ni+1.17+ is bonded in a rectangular see-saw-like geometry to four equivalent Sb3- atoms. All Ni–Sb bond lengths are 2.69 Å. In the fourth Ni+1.17+ site, Ni+1.17+ is bonded to five Te2- atoms to form NiTe5 square pyramids that share corners with four equivalent NiTe5 square pyramids, corners with twelve NiSb2Te2 tetrahedra, edges with four equivalent NiTe5 square pyramids, and edges with four equivalent NiSb2Te2 tetrahedra. There are one shorter (2.51 Å) and four longer (2.70 Å) Ni–Te bond lengths. Sb3- is bonded to twelve Ni+1.17+ atoms to form a mixture of corner and face-sharing SbNi12 cuboctahedra. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 5-coordinate geometry to five Ni+1.17+ atoms. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to eight Ni+1.17+ atoms.