Thermoelectric Properties Of PbS-based Materails Synthesized By Hydrothermal Method

Today, as the accelerating of environmental pollution and energy crisisproblemes, the development of eco-friendly new energy materials have receivedextensively attention from all over the world. Thermoelectric material is a kind ofmaterial which can not only convert thermal energy into electrical energy directly, butalsois pollution-free, high performance with wide application prospect in the field ofsolar energy, geothermal, generate power from industrial waste heat and so on. In thispaper, pure PbS and PbS with different doping were systhesized by hydrothermalmethod. The PbS powders with different components were consolidated into bulkceramic by spark plasma sintering (SPS) and cold press, respectively, themicrostructure and thermal properties of the materials were characterized. The maincontents of the thesis are as follows:(1) PbS powders were synthesized by hydrothermal method, the influence of thesynthesis process on the morphology was studied by changing the temperature of thehydrothermal process and the addition of the surfactant. The results showed thatdendritic PbS powders were systhesized without the addition of the surfactant, and thegrain size reduce with the increased synthesis temperature. Moreover, the morphologyof the PbS powder changed with the added surfactant, and the grain size was furtherreduced.(2) Pure PbS powders were synthesized by hydrothermal method at150°C and180°C, and then the two kinds of powders were consolidated into bulk ceramic byspark plasma sintering (SPS) and cold press, respectively. CThe microstructure ofsamples before and after sintering were characterized by scanning electronmicroscope (SEM), obvious crack was found in the sample consolidated by cold-pressprocess. The results of thermoelectric performance test showed that the ZT value ofthe two samples consolidated by SPS and cold press both increase with the increasedtemperature, the corresponding maximum ZT value at the highest test temperaturewere0.29and0.16respectively.(3) The Bi2S3doped PbS powders with different component were systhesized byhydrothermal method and the powders were consolidated into bulk ceramic by sparkplasma sintering (SPS). The thermoelecteric performance test results showed that thethermal conductivity of the doped samples were reduced and the corresponding conductivity were increased simultaneously. The ZT value of all the samples wereincrease with the increased temperature, and the maximum ZT value increased from0.29to0.55when the dopping content reached1%.(4) The Bi2S3and Cu2S co-doped PbS powder were systhesized by hydrothermalmethod and were consolidated into bulk ceramic by SPS too. The XPS results showedthat Bi2S3and Cu2S were doped into PbS successfully. The effcet of doping Cu2S onthe grain morphology and size of PbS was not obvious. When both the doping contentof Bi2S3and Cu2S reached1%, the corresponding ZT value and the power factorreached0.83and6.5μWcm-1k-2at773K，respectively.