Thermoelectric properties of Ag-doped n-type (Bi2Te3)0.9–(Bi2−xAgxSe3)0.1 (x=0–0.4) alloys prepared by spark plasma sintering

Ag-doped n-type (Bi2Te3)0.9–(Bi2−xAgxSe3)0.1 (x=0–0.4) alloys were prepared by spark plasma sintering and their physical properties evaluated. When at low Ag content (x=0.05), the temperature dependence of the lattice thermal conductivity follows the trend of (Bi2Te3)0.9–(Bi2Se3)0.1; while at higher Ag content, a relatively rapid reduction above 400 K can be observed due possibly to the enhancement of scattering of phonons by the increased defects. The Seebeck coefficient increases with Ag content, with some loss of electrical conductivity, but the maximum dimensionless figure of merit ZT can be obtained to be 0.86 for the alloy with x=0.4 at 505 K, about 0.2 higher than that of the alloy (Bi2Te3)0.9–(Bi2Se3)0.1 without Ag-doping.