Synthesis and Characterization of AgPb₁₈SbTe₂₀ doped with PbI₂

Abstract

  We attempted to synthesize solidified AgPb₁₈SbTe₂₀ doped with PbI₂, which is an n-type dopant for PbTe, and evaluated its electrical and thermal conduction properties in order to investigate the possibility of improving its performance. Large amounts of dispersed and interconnected precipitates with a size of approximately 100 μm were observed, and small cobweb-like precipitates were observed in these precipitates. The consistency of Ag, Sb, Te, and I in these areas was found to be higher than that in other areas. It is suggested that the precipitates are AgSbTe₂. The consistency of Ag in the small cobweb-like precipitates was found to be higher than that in other areas. It was evident that the carrier density at room temperature was approximately three times higher than that of undoped AgPb₁₈SbTe₂₀. It was found that the figure-of-merit at room temperature was 2.4 times higher than that of undoped AgPb₁₈SbTe₂₀. The temperature dependence of 1/(resistivity ρ × thermal conductivity κ), which is a factor of the performance of thermoelectric materials, was evaluated. It was found that 1/(ρκ) is larger than that of undoped AgPb₁₈SbTe₂₀ at temperatures below 170°C. It was suggested that doping of PbI₂ contributed to the improved thermoelectric performance.