Microstructure and thermoelectric properties of Sr0.9La0.1TiO3/TiO2 biphase composite ceramics

Abstract As a well-known n-type perovskite thermoelectric oxides, SrTiO3 has always captured attention to find strategies for achieving high thermoelectric performance. In this paper, a series of reduced Sr0.9La0.1TiO3/TiO2 biphase composite ceramics were prepared via the solid-state reaction method. The effects of TiO2 on the microstructure and thermoelectric properties of the ceramics were investigated. The addition of TiO2 enhanced the carrier mobility via the formation of A-site cation vacancies and increased the carrier concentration probably through introducing oxygen vacancies in rutile TiO2 during the reduction process. Moreover, the additional phonon scattering provided by the interface between the second phase and matrix and oxygen vacancies decreased the thermal conductivity. When the TiO2 addition ratio was optimized to 25 wt%, a large power factor of 1.66 mW/K2/m and the ZT value of 0.24 were achieved at 447 K. The present strategy in this work may be feasible to broaden the range of operating temperature of SrTiO3-based oxide thermoelectric materials.