X-ray powder diffraction studies of Tl2TeBr6 and Tl2TeI6

The crystal structures of Tl 2 TeBr 6 and Tl 2 Tel 6 have been determined using X-ray powder diffraction techniques. Tl 2 TeBr 6 crystallizes in the tetragonal space group P4/mnc, with the lattice parameters: a = 7.468(1) A, c = 10.682(2) A, Z = 2. Tl 2 TeI 6 crystallizes in the monoclinic space group P2 1 /c, with the lattice parameters: a = 7.765(2) A, b = 8.174(2) A, c = 13.756(5) A, β = 124.2(1)°, Z = 2. The Rietveld refinement procedures were stopped when the intensity residuals R B = 0.038 for Tl 2 TeBr 6 and R B = 0.049 for Tl 2 TeI 6 had been reached. The crystal structures of both investigated ternary halides belong to the large family of K 2 PtC 6 -related structures.