Syntheses, crystal structures, and characterization of two new Tl +-Cu 2+-Te 6+ oxides: Tl 4CuTeO 6 and Tl 6CuTe 2O 10

Crystals and polycrystalline powders of two new oxide materials, Tl 4CuTeO6 and Tl 6CuTe 2O 10, have been synthesized by hydrothermal and solid-state methods. The materials were structurally characterized by single-crystal X-ray diffraction. Tl 4CuTeO6 and Tl 6CuTe 2O 10 exhibit one dimensional anionic slabs of [CuTeO 6] 4� and [CuTe 2O 10] 6�, respectively. Common to both slabs is the occurrence of Cu 2+O 4 distorted squares and Te 6+O 6 octahedra. The slabs are separated by Tl + cations. For Tl 4CuTeO 6, magnetic measurements indicate a maximum at �8 K in the temperature dependence of the susceptibility. Low temperature neutron diffraction data confirm no long-range magnetic ordering occurs and the susceptibility was adequately accounted for by fits to a Heisenberg alternating chain model. For Tl 6CuTe 2O 10 on the other hand, magnetic measurements revealed paramagnetism with no evidence of long-range magnetic ordering. Infrared, UV-vis spectra, thermogravimetric, and differential thermal analyses are also reported. Crystal data: Tl 4CuTeO 6, Triclinic, space group P-1 (No. 2), a=5.8629(8)A, b=8.7848(11) A, c=9.2572(12)A, α = 66.0460(10), β = 74.2010(10), γ = 79.254(2), V=417.70(9) A 3, andZ=2; Tl 6CuTe 2O 10, orthorhombic, space group Pnma (No. 62), a=10.8628(6) �, b=11.4962(7)�, c=10.7238(6) �, V= 1339.20(13) � 3, and Z=4. © 2012 Elsevier Inc. All rights reserved.