Density Functional Theory (DFT) perspectives of thermoelectric transportation in Sr-doped LaCoO3

The density functional theory (DFT) approach has been widely used to inquire thermoelectric properties of several classes of materials before their practical deployment. In the present work, a series of Sr-doped LaCoO3 has been modeled to simulate their temperature dependent thermoelectric properties. The calculated band structure reveals metallic nature of all the compositions. The synergetic effects of partial doping of Sr at La-site along with the structural transition of LaCoO3 from cubic to rhombohedral, results in a simultaneous increase in the electrical conductivity and Seebeck coefficient. Furthermore, electrons were the majority charge carriers as evidenced by the negative Seebeck coefficient values. The optimized Sr-doping contents has resulted in the highest power factor (PF) value of 1422 µW/mK2 at 600 K which is about 200 % larger than that of the pure LaCoO3. The highest value for dimensionless figure-of-merit (ZT) is 0.069 which is slightly overestimated because the lattice thermal part of the total thermal conductivity was ignored. These findings paved a valuable path to understand the intriguing doping effects over structural and thermal transportation mechanism in LaCoO3.