Microstructure and thermoelectric properties of La0.1Dy0.1SrxTiO3 ceramics

La0.1Dy0.1SrxTiO3 (x=0.80, 0.78, 0.75, 0.70) powders were synthesized via a sol-gel method, followed by sintering at 1550 °C in a reducing atmosphere of 5 vol% hydrogen in nitrogen. The microstructure and thermoelectric properties of the Sr-deficient La and Dy co-doped SrTiO3 were investigated. The result of XRD revealed that La0.1Dy0.1SrxTiO3 consisted of SrTiO3 with a cubic crystal structure as the main phase and of a small amount of Dy2Ti2O7 as the second phase. All the Sr-deficient samples exhibited a step-like microstructure. As the nominal Sr deficient content increased, the electrical conductivity of the Sr-deficient La0.1Dy0.1SrxTiO3 ceramics enhanced due to the increasing Sr and oxygen vacancies, the absolute value of the Seebeck coefficient increased a little, and the thermal conductivity decreased to ~3.0 W m−1 K−1, leading to a high ZT value of 0.19 for La0.1Dy0.1Sr0.75TiO3 at 500 °C.