Enhanced Thermoelectric Performance in Na/Se Doped p-type AgSbTe_2 Compound

Two types of Na-doped and Na/Se co-doped polycrystalline,sintered samples of p-type AgSbTe2 thermo-electric compounds were prepared from high purity elements by a melt-quench technique followed by spark plasma sintering(Ⅰ: with excess Na or Na/Se,AgNa0.01SbTe2,AgNa0.01SbTe2Se0.04;Ⅱ : replacing corresponding elements by Na or Na/Se,Ag0.99Na0.01SbTe2,Ag0.99Na0.01SbTe1.96Se0.04).The impacts of Na-doping,Na/Se co-doping and doping form on electrical and thermal transport properties were investigated.Meanwhile,by comparing the thermoelectric performance of samples with different kinds of doping form,the optimal doping method is obtained.That is Na re-placing Ag,Se replacing Te with appropriate amount of excess Se.Due to the elevation of Seebeck coefficient by Na-doping and optimization of electrical and thermal conductivities by Se-doping,a maximum of ZT merit of 1.4 is achieved at 620 K for sample Ag0.99Na0.01SbTe1.96Se0.04,representing a 17% enhancement with respect to the undoped sample at the same temperature.