Colloidal synthesis and thermoelectric properties of La-doped SrTiO3 nanoparticles

Abstract

We describe n-type nanostructured bulk thermoelectric La-doped SrTiO₃ materials produced by spark plasma sintering of chemically synthesized colloidal nanocrystals. The La doping levels could be readily controlled from 3 to 9.0 at% by varying the experimental conditions. We found that nanoscale interfaces were preserved even after the sintering process, and the thermoelectric properties of the nanostructured bulk La-doped SrTiO₃ were characterized. An enhanced thermoelectric efficiency was observed and attributed to the large decrease in thermal conductivity obtained with no significant change in the Seebeck coefficient or electrical conductivity. The nanostructured bulk of the La-doped SrTiO₃ exhibited a maximum ZT of ∼0.37 at 973 K at 9.0 at% La doping, which is one of the highest values reported for doped SrTiO₃. Furthermore, the materials showed high thermal stability, which is important for practical high-temperature thermoelectric applications. This report demonstrates the high potential for low-cost thermoelectric energy production using highly stable and inexpensive oxide materials.