Key to enhance thermoelectric performance by controlling crystal size of strontium titanate

One-step molten salt synthesis process was introduced to fabricate nano to micrometer sized SrTiO₃ powders in which effects of synthesis temperature, oxide-to-flux ratios and raw materials on the generation of SrTiO₃ powders were examined. 100 nm or above sized pure SrTiO₃ particles were obtained at relatively lower temperature of 900°C. Micro-sized rhombohedral crystals with a maximum size of approximately 12 μm were obtained from SrCO₃ or Sr(NO₃)₂ strontium source with 1:1 O/S ratio. Controlled crystal size and morphology of Nb-doped _SrTiO3 particles are prepared by using this method to confirm the performance of thermoelectric properties. The Seebeck coefficient obtained is significantly high when compared with the reported data, and the high ratio of nano particles in the sample has a positive effect on the increase of Seebeck coefficient too, which is likely due to the energy filtering effect at large numbers of grain boundaries resulting from largely distributed structure.