The Effect of Porosity and Milling Induced Defects on the Thermoelectric Properties of p‐Type Bi2Te3‐Based Bulks

The p‐type (Bi,Sb) 2 Te 3 bulks are prepared from ball‐milling powders by resistance pressure sintering method and their thermoelectric properties are investigated as a function of ball milling time. Prolonging milling time would introduce more anti‐site defects, interaction of vacancies and antisite defect, grain‐boundaries and interface defects, leading to lower carrier concentration and mobility. The peak value of ZT = 1.0 is achieved at 300 K for the 5 h sample. When the testing temperature is over 323 K, the ZT value of the 0 h sample is higher than that of the 5 h sample. The effect of porosity on the thermoelectric properties is also investigated by effective medium theory. As the porosity increased, the electrical resistivity increases and the thermal conductivity decrease.