Abnormal Crystal Growth and Transport Properties of Sintered (Bi_0.2Sb_0.8)₂Te₃ Thermoelectric Alloys with Ag Addition

抄録

A combination of mechanical alloying and pulse discharge sintering was employed to fabricate the bulk (Bi_0.2Sb_0.8)₂Te₃ thermoelectric alloys with addition of Ag up to 1.0mass%. Addition of Ag up to 0.5mass% has little influence on the microstructure of the compact. However, when 1.0mass% Ag was added, an abnormal grain growth was observed in the compact during sintering at 618K. In this bulk sample, Ag particles were detected by scanning/transmission electron microscope. Thermoelectric property measurements indicate that addition of Ag optimizes the power factor, but simultaneously considerably enhances the thermal conductivity and finally markedly degrades the room-temperature figure of merit of the (Bi_0.2Sb_0.8)₂Te₃ alloy.