Phase transformation and thermoelectric properties of p-type (Bi2Te3)0.25(Sb2Te3)0.75 prepared by mechanical alloying and hot pressing

Starting from elemental powder mixtures, p-type (Bi2Te3)0.25(Sb2Te3)0.75 thermoelectric alloys were fabricated via mechanical alloying (MA) and hot pressing in the present work. With the MA process proceeding, elemental Bi, Sb and Te reacted into (Bi2Te3)0.25(Sb2Te3)0.75 solid solution phase, the amount of the solid solution phase increased with prolonging MA time, and single phase (Bi2Te3)0.25(Sb2Te3)0.75 was obtained after MA for 12 h. Microstructure and thermoelectric properties of the hot-pressed samples were investigated. P-type (Bi2Te3)0.25(Sb2Te3)0.75 with slightly preferred orientation and fine grain size were obtained after hot pressing. The maximum figure of merit was obtained as 2.84 × 10−3 K−1 at room temperature.