Effect of Bi³⁺ Doping on the Electronic Structure and Thermoelectric Properties of (Sr_0.889-xLa_0.111Bi_x)TiO_2.963: First-Principles Calculations

The electronic structure and thermoelectric properties of Bi³⁺-doped (Sr_0.889-xLa_0.111Bi_x)TiO_2.963 were studied by the first principles method. Doping Bi³⁺ can increase the cell parameters, cell asymmetry and band gap. With increasing Bi³⁺ content, the asymmetry of DOS relative to the Fermi level increases, which results in an enhanced Seebeck coefficient, increasing carrier mobility and decreasing carrier concentration. An appropriate Bi³⁺-doping concentration (7.4–14.8%) can increase the lattice distortion and reduce the lattice thermal conductivity of the material. An appropriate Bi³⁺-doping concentration (7.4%) can effectively optimize the electrical transport performance and improve the thermoelectric properties of strontium titanate. The optimal Bi³⁺-doping concentration is 7.4%, and Sr_0.815La_0.111Bi_0.074TiO_2.963 obtains a maximum ZT of 0.48. This work shows the mechanism of Bi³⁺ doping in enhancing the thermoelectric properties of strontium titanate.