Enhanced Figure-of-Merit in Se-Doped p-Type AgSbTe2 Thermoelectric Compound

Polycrystalline, sintered samples of p-type AgSbSexTe2−x (x = 0−0.04) were prepared from high purity elements by a melt-quench technique followed by spark plasma sintering. X-ray diffraction and differential scanning calorimetry thermal analysis indicate that a small amount of Se doping (x ≥ 0.02) can effectively inhibit the emergence of the Ag2Te and Ag0.35Sb0.09Te0.56 impurity phases. Therefore, samples with x ≥ 0.02 form a homogeneous single-phase solid solution and in the temperature range 400−700 K have considerably larger electrical conductivity compared with that of samples with x = 0 and x = 0.01. Combined with a low lattice thermal conductivity, samples with x ≥ 0.02 have a higher figure of merit ZT that reaches values of 1.37 at 565 K, representing a 26% enhancement with respect to an undoped AgSbTe2 at the same temperature. The results indicate that doping with Se is an effective way to enhance the thermoelectric performance of p-type AgSbTe2.