Ultrahigh electrical conductivities and low lattice thermal conductivities of La, Dy, and Nb Co-doped SrTiO3 thermoelectric materials with complex structures

Microstructural modifications and appropriate element doping are necessary to simultaneously enhance the electrical conductivities and reduce the lattice thermal conductivities of thermoelectric materials . Herein, we propose a strategy of multielement doping combined with a burial sintering process to promote thermoelectric properties. Three-element doped Sr 0.9 La 0.05 Dy 0.05 Ti 1− x Nb x O 3 ( x = 0, 0.05, 0.10, 0.15, and 0.20) powders were synthesized by high-energy ball milling, and corresponding bulk samples were prepared by carbon burial sintering. In the bulk samples, we obtained the desired microstructures composed of shell-vesicular architectures with dense dislocations and second phase particles. These materials had ultrahigh electrical conductivities (∼5300 S cm −1 at 300 K), low lattice thermal conductivities (∼1.6 W m −1 K −1 from 700 to 1100 K when x = 0.2) and low total thermal conductivities (minimum value of 2.95 W m −1 K −1 when x = 0.05 at 1100 K). The maximum zT values were 0.28 when x = 0.05 and 0.27 when x = 0.2 at 1100 K. This strategy provides a possible direction for improving the thermoelectric properties of SrTiO 3 based materials.