Major enhancement of the thermoelectric performance in Pr/Nb-doped SrTiO₃ under strain

The electronic structure and thermoelectric properties of strained (biaxially and uniaxially) $Sr0.95Pr0.05TiO3$ and $SrTi0.95Nb0.05O3$ are investigated in the temperature range from 300 K to 1200 K. Substitutions of Pr at the Sr site and Nb at the Ti site generate n-type doping and thus improve the thermoelectric performance as compared to pristine SrTiO₃. Further enhancement is achieved by the application of strain, for example, of the Seebeck coefficient by 21% for $Sr0.95Pr0.05TiO3$ and 10% for $SrTi0.95Nb0.05O3$ at room temperature in the case of 5% biaxial strain. At 1200 K, we predict figures of merit of 0.58 and 0.55 for 2.5% biaxially strained $Sr0.95Pr0.05TiO3$ and $SrTi0.95Nb0.05O3$⁠, respectively, which are the highest values reported for rare earth doped SrTiO₃.