Effect of Ag⁺ doping and Ag addition on the thermoelectric properties of KSr₂Nb₅O₁₅

The electron and phonon thermal transport behavior of Ag ⁺ doped KSr₂Nb₅O₁₅ were discussed by using the first-principles calculations. The band gap was reduced after Ag⁺ doping, and the electrons near the Fermi level had stronger transition capability, which effectively increased the carrier concentration and electrical conductivity and reduced the thermal conductivity, thereby improving the ZT of the doped KSr₂Nb₅O₁₅ from 0.6298 to 0.7214 (1200 K) under ideal conditions. In addition, the solid-state reaction method was used to prepare Ag nanoparticle added KSr₂Nb₅O₁₅ samples, and their thermoelectric performance was tested. The experimental results and the calculated results showed a good consistent trend in which Ag improved the thermoelectric properties of KSr₂Nb₅O₁₅. When the amount of addition of nanosized Ag was 20 wt%, the power factor and ZT of the material were the highest at 1073 K, which were 0.228 mW/(K²·m) and 0.1090, respectively. This research shows how to improve the thermoelectric performance of KSr₂Nb₅O₁₅ ceramics and broaden their temperature range for application.