Thermoelectric properties of Yb-doped La0.1Sr0.9TiO3 ceramics at high temperature

The effect of ytterbium doping on the thermoelectric properties of La0.1Sr0.9TiO3 ceramics has been investigated at the temperature range between 300 K and 1000 K. Samples with different ytterbium concentrations have been synthesized by the conventional solid state reaction technique. An X-ray diffraction pattern suggests that the dominant crystal structure is of perovskite, with a small amount of pyrochlore phase of Yb2Ti2O7. The electrical resistivities of all samples exhibit a minimum in the temperature range between 300 K and 1000 K. The minimum values of electrical resistivity are 1.5 mΩ cm, 2.0 mΩ cm, 3.9 mΩ cm, 7.1 mΩ cm, and 9.0 mΩ cm for x=0.01, 0.03, 0.05, 0.07, and 0.10, respectively. With the increasing ytterbium content, the electrical resistivity enhanced dramatically, the Seebeck coefficients are increased marginally, and the thermal conductivities are reduced moderately. The lowest thermal conductivity of 3.9 W/mK is obtained in sample of La0.1Sr0.89Yb0.01TiO3, which exhibits maximum figure of merit 0.20 at 963 K.