Synthesis, crystal structure and thermoelectric properties of a new metal telluride Ba3Ag3InTe6. Issue 9 (14th June 2017) - Lee, M.-Y.
Abstract : A new p-type semiconductor Ba3 Ag3 InTe6 with transport properties dominated by the layer [Ag3 Te4 ] 5− distributed in the valence band. Abstract : A new metal telluride Ba3 Ag3 InTe6 was synthesized by a solid-state reaction at 650 °C. Crystal data: Orthorhombic, Cmc 21, a = 4.5669(3) Å, b = 27.9366(16) Å, c = 13.3819(8) Å, V = 1707.3(2) Å 3, and Z = 4. This compound adopts a new two-dimensional structure constructed by AgTe4 and InTe4 tetrahedra and Ba 2+ cations. The edge-sharing AgTe4 tetrahedra form a puckered layer of [Ag3 Te4 ] 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.