  The thermoelectric properties of Sr0.61Ba0.39Nb2O6 ceramics, reduced in
different conditions, were investigated in the temperature region from 323 K to
1073 K. The electrical transport behaviors of the samples are dominated by the
thermal-activated polaron hopping, the Fermi glass behavior, and the Anderson
localized behavior from low temperatures to high temperatures, respectively.
The lattice thermal conductivity presents a plateau at high temperatures,
indicating a glass-like thermal conduction behavior. Both the thermoelectric
power factor and the thermal conductivity increase with the increasing degree
of oxygen-reduction. Taking these two factors into account, the
oxygen-reduction can still contribute to promoting the thermoelectric figure of
merit. The highest ZT value (~0.19 at 1073 K) is obtained in the heaviest
oxygen reduced sample.
