Shift of tellurium solid-solubility limit and enhanced thermoelectric performance of bismuth antimony telluride milled with yttria-stabilized zirconia balls and vessels

As a thermoelectric material, Bi0.3Sb1.7Te3.0+x (x = 0‒0.05) was fabricated by mechanical alloying using yttria-stabilized zirconia (YSZ) ceramic balls and vessels, followed by hot pressing. The effects of the added tellurium on the thermoelectric properties of Bi0.3Sb1.7Te3.0 fabricated with YSZ milling media were investigated. All sintered samples were isotropic and showed p-type conduction. The tellurium solid-solubility limit for Bi0.3Sb1.7Te3.0 was determined to be x = 0.01 by differential thermal analysis (DTA). The solid-solubility limit of the sample fabricated using YSZ was narrower than that of the congener prepared with Si3N4 balls and stainless-steel metal vessels. Among the evaluated compositions, the Bi0.3Sb1.7Te3.01 sintered disk had the highest dimensionless figure of merit, ZT = 1.30, at room temperature. This value was superior to that of Bi0.3Sb1.7Te3.0+x fabricated using metal vessels. Thus, selection of the milling media affected the optimum doping amount and maximum ZT.

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