Thermoelectric properties of fine-grained sintered (Bi2Te3)25-(Sb2Te3)75 p-type solid solution
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P-type semiconductor alloy compacts of the composition (Bi2Te3)25-(Sb2Te3)75 with grain size (L) in the range 30 > L > 20 μm, 20 > L > 15 μm, 15 > L > 10 μm, 10 > L > 5 and L < 5 μm were prepared by cold press at a pressure of 77 × 107 Nm−2. The samples were sintered at 673 K. Measurements of the Seebeck coefficient, electrical resistivity and thermal conductivity were carried out. The experimental results show that the Seebeck coefficient increases, but not much from the single crystal. The electrical resistivity increases in particular for the size L < 5 μm with a reduction in grain size. The total thermal conductivity seriously decreases as grain size decreases. It is concluded that the figure of merit of the compacted alloy would be significantly improved through the use of fine-grained powders of size 30−10 μm.
KeywordsGrain Size Thermal Conductivity Solid Solution Electrical Resistivity Material Processing
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