EFFECT OF SINTERING TEMPERATURE ON THE PROPERTIES OFPOWDERED (Bi_(0.25)Sb_(0.75))_2Te_3THERMOELECTRIC COMPOUND SINTEREDAT SEVERAL TEMPERATURES

摘要

(Bi_(0.25)Sb_(0.75))_2Te_3thermoelectric material was powdered and sintered by heating the powder up to350-500 °C under pressure of 500MPa. The microstructures of sintered materials were found to bewell aligned along the basal planes in transverse direction, particularly when sintered at lowertemperatures. Carrier concentration, electrical and thermal conductivities in transverse directionwere higher than those in longitudinal direction by a factor of about 3 when sintered at lowtemperatures. The factor arose with increasing the sintering temperature, particularly whenexceeded 500 °C. Generally, both the electrical and thermal conductivity of the material increasedwith increasing sintering temperature. Seebeck coefficient in longitudinal direction was more orless equal compared to that in the transverse direction, and showed a general tendency todecrease with increasing sintering temperature. In terms of power factor (a~2σ), optimum sinteringcondition is 500 °C, leading to a maximum (a~2σ) value of around 61.7 and 21.00 pWK2, intransverse and longitudinal directions, respectively.