Enhancing the thermoelectric properties of Nb-doped TiO2 -based ceramics through in-situ synthesis of β-Sn inclusions at grain boundaries

Significantly enhanced thermoelectric performance of Nb-doped TiO2 ceramics has been achieved through in-situ formation of beta-Sn grain boundary inclusions. The ceramics were prepared by mixed oxide route and sintered at 1473 K (lower than usual for TiO2) and strongly reducing conditions. All sample microstructures contain a high density of beta-Sn structured inclusions at grain boundaries which assist densification. A variety of crystalline de- fects occur inside the rutile grains; the beta-Sn inclusions contain nano-regions with severe lattice distortion. Through the formation of a highly conductive beta-Sn phase, the carrier concentration and electrical conductivity were significantly enhanced, resulting in a similar to 27% increase in power factor and much-improved ZT values of 0.20 at 873 K. Our approach based on grain boundary engineering provides a simple and eco-friendly route to enhance the thermoelectric performance of low-cost, oxide-based ceramics.

Automated summary

Significantly improved thermoelectric performance of Nb-doped TiO2 ceramics was achieved by forming beta-Sn grain boundary inclusions in situ. The ceramics were prepared through a mixed oxide route and sintered at a lower temperature of 1473 K under strongly reducing conditions. The introduction of beta-Sn inclusions at grain boundaries greatly assisted densification and enhanced carrier concentration and electrical conductivity, resulting in a 27% increase in power factor and improved ZT values of 0.20 at 873 K. This grain boundary engineering approach offers a simple and eco-friendly method to enhance the thermoelectric performance of low-cost oxide-based ceramics.