Thermoelectric properties of PbTe/Ag bulk materials fabricated by electroless silver plating and spark plasma sintering

• Main Authors: Yi-HsuanTang, 唐宜萱
• Other Authors: Chii-Shyang Hwang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/79180886821281579421

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 101 === For changing carrier concentration and increasing electrical conductivity and Seebeck coefficient, and then enhancing the power factor of the PbTe/Ag bulk materials, in this study, PbTe/Ag hybrid powders were prepared using the electroless plating methods and sintered by spark plasma sintering (SPS) at 50 MPa from 300 oC to 400 oC. Effects of Ag comtents and SPS temperatures on the microstructures and thermoelectric properties of PbTe/Ag bulks were investigated. The amounts of silver particles coating on the PbTe powders could be controled by adding the suitable amounts of the reducing agent, and the sizes of silver particles were 100 ~ 200 nm. After SPS sintering, the silver not only agglomerated in micro-scale on the grain boundaries of the PbTe but also formed solid solution in PbTe, including interstitial mainly and substitutional solid solutions. The electric conductivity of PbTe/Ag bulks could be transformed from p-type to n-type with the increase of silver. The power factor of PbTe/Ag bulks increased with the silver contents and the sintering temperatures. The maximum ZT value, 0.27, was obtained from the PbTe/Ag bulk material prepared by SPS at 400 oC with 6.81 wt% silver measured at 610 K. The carrier concentration of the n-type PbTe/Ag (with 8.96 wt% Ag) bulk materials at room temperature decreased with increasing SPS sintering temperatures. The relative densities, carrier mobilities and Seebeck coefficients of the bulk materials all increased with sintering temperatures. of The PbTe/Ag-400 oC bulk material with 8.96 wt% sliver had the maximum power factor,1.15 mW/m-K2 at 609 K, which was 28 times higher than PbTe-400 oC bulk without silver.