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Abstract: As a p-type semiconductor, Ga2Te5 has very low Seebeck coefficient and thermal conductivity. Cu, Sb co-doped Ga2Te5 based semiconductor was prepared by spark plasma sintering technique, and its band gap was measured decreasing from ΔEg//=1.77eV represented by intrinsic state to 1.50eV. X-ray analysis reveals the material crystallizes in the main phase Ga2Te5, but with Ga2Te3 and Sb2Te3 minor phases precipitated. The Seebeck coefficient increases from 150 (μV/K) to 275 (μV/K) with temperature elevation, while the electrical conductivity decrease from 5.2×103 (Ω-1. m-1) to 2.4×103 (Ω-1. m-1), but still much higher than that of single crystal of Ga2Te5 reported at the corresponding temperature. The great improvement of electrical properties is closely related to the band gap narrowing, even though the impurity phases precipitated can influence the measured band gap value. The highest ZT value of 0.21 was obtained at 631 K for the Cu, Sb co-doped Ga2Te5 based semiconductor. [Copyright &y& Elsevier]

Abstract: A novel ternary Ag-In-Se semiconductor was prepared using spark plasma sintering technique, and its crystal structure and thermoelectric properties were evaluated. XRD analysis and bandgap measurement indicated that this ternary compound crystallizes in a single phase AgIn5Se8 with its bandgap of 1.11 eV, smaller than that of In2Se3, it therefore is of higher electrical conductivity than In2Se3. The highest power factor and thermoelectric figure of merit ZT, thermal conductivity at 863 K are 2.74x10-4 W.K-2 .m-1, 0.61 and 0.39 W.K-2 .m-1, respectively. [Copyright &y& Elsevier]

MoS 2 nanosheets with size of several-hundred nanometers were prepared by a hydrothermal intercalation/exfoliation method, then MoS 2 /Bi 2 Te 3 composite nanopowders were prepared by a microwave-assisted wet chemical method using the MoS 2 nanosheets, TeO 2 , Bi(NO 3 ) 3 ·5H 2 O, KOH and ethylene glycol as raw materials. Bulk MoS 2 /Bi 2 Te 3 nanocomposites were prepared by hot pressing the MoS 2 /Bi 2 Te 3 composite nanopowders with MoS 2 nanosheet content ranging from 0 to 17 wt% at 80 MPa and 648 K in vacuum. X-ray photoelectron spectroscopy and X-ray diffraction analyses indicate that MoS 2 and Bi 2 Te 3 did not react each other during the hot pressing. FESEM observation reveals that the MoS 2 /Bi 2 Te 3 composite samples had a more compact microstructure than the pristine Bi 2 Te 3 bulk sample. The MoS 2 phase was relatively randomly dispersed in the composite. At a given temperature, the electrical conductivity of the composites increases first then decreases as the MoS 2 content increases, whereas the Seebeck coefficient of the bulk nanocomposites does not change much. A highest power factor, ~18.3 μW cm −1 K −2 which is about 30% higher than that of pristine Bi 2 Te 3 sample, at 319 K has been achieved from a nanocomposite sample containing 6 wt% MoS 2 . [ABSTRACT FROM AUTHOR]