Effect of (Pb,Ge)Te addition on the phase stability and the thermoelectric properties of AgSbTe2

Although AgSbTe2 exhibits excellent thermoelectric properties, the single phase is unstable and second phases such as Ag2Te and Sb2Te3 are easy to precipitate. In the present study, we tried to stabilize the AgSbTe2 phase by adding a small amount of another phase. Here we chose Pb0.16Ge0.84Te as the adding phase because the crystal structure and the lattice parameter were completely the same as those of AgSbTe2. The samples of (Ag0.5Sb0.5Te)(1-x)(Pb0.16Ge0.84Te)(x) (x = 0, 0.01, 0.02, 0.05, and 0.1) were prepared and the phase stability and the thermoelectric properties were examined. The AgSbTe2 phase was stabilized in the samples of x = 0.01 and 0.02. All the samples exhibited large thermoelectric figure of merit.