Enhancement of thermoelectric performances of BiCuSeO through Y doping and grain refining

Thermoelectric properties of BiCuSeO oxyselenide ceramics were improved combining Y doping and grain refinement. Bi1−xYxCuSeO (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) (called as BYCSO below) samples were prepared by mechanical alloying and resistance pressing sintering (RPS). The testing results indicate that Y doping can increase the carrier concentration and electrical conductivity, increase the thermal conductivity. On the basis of Y doping, grain refinement by increasing ball milling strength was indicated to increase the concentration of Cu vacancies, which enhanced the electrical conductivity and power factor, and reduce the thermal conductivity. Finally, the ZT value is increased to 0.93, which is 98% higher than that of the pure sample.