Synthesis, crystal structure and thermoelectric properties of a new metal telluride Ba3Ag3InTe6

Abstract

A new metal telluride Ba3Ag3InTe6 was synthesized by a solid-state reaction at 650 °C. Crystal data: Orthorhombic, Cmc21, a = 4.5669(3) Å, b = 27.9366(16) Å, c = 13.3819(8) Å, V = 1707.3(2) Å3, and Z = 4. This compound adopts a new two-dimensional structure constructed by AgTe4 and InTe4 tetrahedra and Ba2+ cations. The edge-sharing AgTe4 tetrahedra form a puckered layer of [Ag3Te4]5- and the corner-sharing InTe4 tetrahedra form a zig-zag chain of [InTe2]- that dangles from both edges of the layer. The band gap determined by UV-vis-NIR absorption spectra is estimated to be around 0.48 eV. This compound is a p-type semiconductor with high Seebeck coefficients of 325-334 μV K-1 in an entire temperature range of 320-400 K. The electrical conductivity of 9.4 S cm-1 and the thermal conductivity of 0.35 W mK-1 give a ZT value of 0.11 at 400 K. The electronic band structure reveals a direct band gap at the Γ point of the face centered primitive Brillouin zone. The density of states (DOS) analysis shows that the p-type hole transport is mostly achieved through the layer consisting of AgTe4 tetrahedra. © 2017 the Partner Organisations.