Synthesis, structures, and conductivities of the new layered compounds Ta3Pd3Te14 and TaNiTe5

The new layered ternary chalcogenides Ta3Pd3Te14 and TaNiTe5 have been prepared by high-temperature reactions of the elements. They have been characterized by single crystal X-ray diffraction methods. The compound Ta3Pd3Te14 crystallizes with two formula units in the monoclinic space groupC22h-P21m in a cell with dimensionsa = 14.088(19), b = 3.737(3), c = 20.560(19)Å, and β = 103.73(5)°. TaNiTe5 crystallizes with four formula units in the orthorhombic space groupD172h-Cmcm in a cell with dimensionsa = 3.659(2), b = 13.122(10), c = 15.111(11)Å. Both are layer structures. TaNiTe5 is isostructural with the previously synthesized compound NbNiTe5. The layers for TaNiTe5 contain Ta atoms in a bicapped trigonal prismatic Te environment and Ni atoms in an octahedral environment. The layers for Ta3Pd3Te14 are made up of octahedral and bicapped trigonal prismatic Ta atoms and octahedral Pd atoms coordinated by Te. Electrical conductivity measurements indicate that both of these compounds are metallic; for Ta3Pd3Te14,σ297 ≈ 2.2 × 103 Ω−1cm−1 and for TaNiTe5,σ297 ≈ 2.6 × 104 Ω−1cm−1. Magnetic susceptibility measurements show that TaNiTe5 is paramagnetic.