Sr-Site Deficient La-Sm Co-Doped SrTiO3 Thermoelectric Ceramics

Abstract

The phase, microstructural and thermoelectric properties of Sr1-3x/2Smx/2TiO3 (0.05 x ) ceramics were investigated. Samples with varying concentrations of La3+ and Sm3+ ions were batched, synthesized by solid state reaction (SSR) method, calcined in air and sintered in 5 % H2/N2 at 1773 K for 6 h. The particle size distribution (PSD) showed mean particle size (d50) of 6.0 μm while the surface morphology images from the scanning electron microscopy (SEM) revealed homogenous grain structures with average grain size of 15.3 μm. The lowest total thermal conductivity, k at 573 K was observed in x = 0.30 (3.46 W/m.K), which decreased to a minimum of 2.99 W/m.K for all the compositions at 973 K. k decreased with increasing temperature over the measured temperature range, which suggests a typical thermal conduction behaviour of a semiconductor. Overall, x = 0.30 showed the highest thermoelectric figure of merit, ZT = 0.25 at 973 K.