Structure and properties of triclinic Ni 0.85Mo 6Te 8

Abstract

The structure of Ni 0.85Mo 6Te 8 was refined from single-crystal X-ray diffraction data at room temperature. It is triclinic, space group P 1, a = 7.028(2) A ̊ , b = 7.100(2) A ̊ , c = 7.102(2) A ̊ , α = 91.23(2)°, β = 95.73(2)°, γ = 90.82(2)°, V = 352.48 A ̊ 3, Z = 1 ; 1619 reflections, 75 refined parameters, R = 0.031. The Mo atoms form distorted octahedral clusters (2.69 Å ≤ d intra[MoMo] ≤ 2.81 Å; 3.58 Å < d inter[MoMo]). The Ni atoms are disordered (site occupancy: 0.423(7); d[ NiNi] = 2.586(6) A ̊ ) , and interact strongly with one Mo 6 cluster ( d[ NiMo] = 2.603(3) and 2.958(3) A ̊ ), and weakly with another ( d[ NiMo] = 2.985(3) A ̊ ). The structure transforms at 1057(5) K into a rhombohedral modification ( a hex = 10.457(2) A ̊ , c hex = 11.866(3) A ̊ at 1073 K). Measurements on powders suggest metallic conductivity (5.1 × 10 −4 Ω-cm at 293 K) and weakly temperature-dependent paramagnetism (110 × 10 −6 emu/g at 100 K).