Double perovskite Pr2CoFeO6 thermoelectric oxide: roles of Sr-doping and micro/nanostructuring

Double perovskite Pr2CoFeO6 thermoelectric oxide: roles of Sr-doping and micro/nanostructuring

Owing to their excellent thermal stability, non-toxicity, and low cost, oxide-based thermoelectric materials have considerably expanded research interests and industrial application. Here, we, for the first time, report a new-type Pr2CoFeO6 oxide-based thermoelectric materials from both theoretical and experimental aspects. Our first-principles calculation results indicate that Pr2CoFeO6 is a p-type semiconductor with narrow bandgap. The experimental thermoelectric evaluation shows that pristine Pr2CoFeO6, synthesized by a combination of sol-gel method and conventional sintering, has a peak figure of merit, ZT of 0.015 at 773 K with a high positive Seebeck coefficient of 250 μV K-1 and very low thermal conductivity of 0.7 W m-1 K-1 at this temperature. Further Sr2+ doping on Pr-sites (Pr3+) enhances the carrier concentration from 4.03×1014 cm-3 to 5.22×1017 cm-3, contributing to an improved power factor up to 46 μW m-1 K-2. Besides, Sr-doping induces point defects in the matrix and further suppresses the thermal conductivity to 0.58 W m-1 K-1, leading to a promising ZT up to 0.05 at 673 K in Pr1.8Sr0.2CoFeO6, which is significantly improved by 233 % compared to pristine Pr2CoFeO6. We also predict that a high ZT of >0.2 can be achieved by the optimization of carrier density, band engineering, and energy filtering, which is comparable to many other oxide-based thermoelectric materials.