Thermoelectric Properties of Combustion Synthesized and Spark Plasma Sintered Sr<SUB>1−<I>x</I></SUB>R<I><SUB>x</SUB></I>TiO<SUB>3</SUB> (R = Y, La, Sm, Gd, Dy, 0<<I>x</I>≤0.1)

Abstract

Thermoelectric properties of combustion synthesized and spark plasma sintered rare-earth-doped (Y, La, Sm, Gd and Dy) SrTiO3 was investigated from room temperature to 870 K toward the viewpoint of energy and time saving without deterioration in thermoelectric properties. All the rare-earth-doped SrTiO3 were successfully synthesized and sintered with high purities and high densities. With temperature increasing, the absolute value of Seebeck coefficient increased and the electric conductivity decreased; the power factor of all the samples decreased except Y-doped sample in the experimental temperature range. In all the samples, the La-doped SrTiO3 and the Y-doped SrTiO3 had the highest and the lowest power factor, respectively. The dimensionless figure of merit ZT of La-doped samples with different doping amount was evaluated and the maximum ZT was 0.22, which was obtained at 800 K from Sr0.92La0.08TiO3 sample. Comparing Y and La-doped samples prepared by our method with that of conventional solid-state reaction method, the thermoelectric properties of our samples were relatively higher. Thus the combination of combustion synthesis and spark plasma sintering has a potential to prepare perovskite-oxide materials with relatively higher thermoelectric properties for high-temperature application.