Influence of Ag_2Te Doping on the Thermoelectric Properties of p-type Bi_(0.5)Sb_(1.5)Te_3 Bulk Alloys

(Ag2Te)x(Bi0.5Sb1.5Te3)1-x(x=0,0.025,0.05,0.1) alloys were synthesized by Melting-Ball Milling-Spark Plasma Sintering method.Transport properties measurements indicate that the Ag2Te-doping can affect the temperature dependence of thermoelectric properties of the samples significantly.Samples with Ag2Te-doping have better thermoelectric performances in the temperature range from 450 K to 550 K.Appropriate amount of Ag2Te can enhance the phonon scattering of the alloys effectively,which lead to the lower thermal conductivities for these samples.Over the entire temperature range,sample(Ag2Te)0.05(Bi0.5Sb1.5Te3)0.95 exhibits the lowest lattice thermal conductivities,ranging within 0.2-0.3 W/(m·K) from room temperature to 575 K.The maximum ZT value of 0.84 is obtained at 575 K for the sample(Ag2Te)0.05(Bi0.5Sb1.5Te3)0.95.Compared with the one without doping,the ZT value is increased by almost 20%.