High electrical conductivity and enhanced thermoelectric properties in La-Nb co-doped (Sr_1/3Ba_1/3Ca_1/3)TiO₃-based oxides

Here, we report a series of (Sr_1/3Ba_1/3Ca_1/3)TiO₃-based oxides with different La-Nb doping levels synthesized by solid-state reaction and graphite-burial sintering method. The results indicate that La-Nb co-doping significantly enhances the electrical conductivity by increasing carrier concentration, leading to a remarkable improvement in power factor (∼1665 μW/(m·K²) at 773 K). Additionally, the lattice thermal conductivity is reduced due to the enhanced phonon scattering caused by point defects and pores. As a result, a peak ZT value of 0.36 at 773 K is achieved for the 5% La-10% Nb co-doped sample, 200% higher compared to the un-doped sample. This work highlights the promising potential of the (Sr_1/3Ba_1/3Ca_1/3)TiO₃-based oxides as environmentally-friendly thermoelectric materials.