Processing bulk insulating CaTiO3 into a high-performance thermoelectric material

Abstract

The development of new high-performance thermoelectric (TE) materials has been garnering significant attention from both the academic communities and industrial fields. Owing to its abundance, eco-friendliness, low cost, and non-toxicity, the oxide CaTiO3 can be considered as a promising high-temperature TE material for large-scale applications. In this regard, this study successfully transformed the insulating CaTiO3 ceramic into a TE material with outstanding TE properties by substituting Ca2+ with La3+ and generating stable oxygen vacancies. The excellent performance of the La-doped samples is mainly attributed to the synergistic effect of La doping and stable oxygen vacancies, which lead to a deeper Fermi energy level and increased density of states. As a result, the power factor was significantly enhanced over a broad temperature range. Coupled with the decreased thermal conductivity resulting from the generated point defects and nano-precipitates to scatter phonons, the desired zT value of 0.4 at 1011 K for bulk Ca0.8La0.2TiO3 was achieved, which was 470% higher than that of pristine bulk CaTiO3. Therefore, our discovery can spark new routes to obtain high-performance TE ceramics and improve their TE performance by introducing dopants and oxygen vacancies.