Medium-entropy (Sr1/3Ba1/3Ca1/3)TiO3 perovskite oxide for thermoelectric applications

A novel ternary medium-entropy perovskite oxide , (Sr 1/3 Ba 1/3 Ca 1/3 )TiO 3 , is reported for thermoelectric applications; it was synthesized via solid-state reaction and graphite burial sintering. The formation and stability of the single-phase structure were evaluated using thermodynamic calculations and the Goldschmidt’s tolerance factor. The material was found to have a single-phase cubic perovskite structure with a homogeneous distribution of all elements. The medium entropy generates moderate carrier mobility , while the band flattening yields high Seebeck coefficient, resulting in a high power factor of 378.8 μW·m −1 ·K −2 at 773 K. The enhanced multi-phonon scattering derived from the medium entropy, oxygen vacancies , and porous structure significantly reduced the lattice thermal conductivity , with a lowest value of 1.90 W·m −1 ·K −1 at 773 K. As a result, a ZT max of 0.13 was attained at 773 K, which outperforms that of high-entropy SrTiO 3 -based oxides. This work provides a new direction to obtain high-performance thermoelectric materials through medium-entropy composition design.