Preparation and thermoelectric properties of la-doped SrTiO ₃ ceramics

Single-phase polycrystalline La _x Sr _1-x TiO ₃ (x = 0, 0.04, 0.06, 0.08, and 0.12) ceramics were prepared by the conventional solid-state reaction method using high-activity hydroxides as the raw materials. The electrical conductivity of all the samples increased with increasing x value and decreased with measurement temperature, while the thermal conductivity decreased with increasing x value and measurement temperature. The La _0.12Sr _0.88TiO ₃ sample showed the lowest thermal conductivity of 2.45 W m ^-1 K ^-1 at 873 K and the largest ZT of 0.28 at 773 K. The present work revealed that hydroxides with high activity as raw materials are beneficial to improve the thermoelectric properties, especially to decrease the thermal conductivity.