Influence of Bi on the thermoelectric properties of SrTiO3-δ

The thermoelectric properties of Sr1-xBixTiO3-delta (0 <= x <= 0.07) have been investigated. Dense ceramics of Sr1-xBixTiO3-delta and Sr0.95TiO3-delta have been prepared by solid-state reaction and conventional sintering in air followed by annealing in a reducing atmosphere. XRD and SEM analyses show that the rutile TiO2 in Sr0.95TiO3 formed after sintering becomes Magneli phase of TinO2n-1 after annealing. Moreover, Bi resolves from Sr1-xBixTiO3 after annealing, resulting in the formation of Sr1-xBixTiO3-delta/Bi/TinO2n-1 composites. With increasing Bi content in Sr1-xBixTiO3-delta, the electrical conductivity increases while the absolute values of the Seebeck coefficient decrease as a result of increasing carrier concentration. The thermal conductivity of SrTiO3-delta is reduced by doping Bi up to x = 0.07. Highest ZT similar to 0.13 is obtained in Sr0.93Bi0.07TiO3-delta at 1000 K. (c) 2018 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.