Thermoelectric Properties of Ag-Doped n-Type (Bi2-xAgxTe3)0.96-(Bi2Se3)0.04 Pseudobinary Alloys

n-Type thermoelectric powders of (Bi2-x Ag (x) Te-3)(0.96)-(Bi2Se3)(0.04) (0 <= x <= 0.05) have been synthesized by mechanical alloying and then consolidated by spark plasma sintering. The analysis results show that the grain size of pure Bi, Te, Ag, and Se powders is decreased to about 1 mu m to 0.5 mu m after they are mechanically alloyed for 2 h. The power factor of bulk material increases with increasing Ag-doping content, while the trend for the lattice thermal conductivity is the opposite. Bulk (Bi0.99Ag0.04)(2)(Te0.96Se0.04)(3) after milling for 12 h exhibits a higher power factor, lower thermal conductivity, and thus a higher ZT of 0.74 at 373 K.