  Magneli phase Ti5O9 ceramics with 200-nm grain-size were fabricated by
hot-pressing nanopowders of titanium and anatase TiO2 at 1223 K. The
thermoelectric properties of these ceramics were investigated from room
temperature to 1076 K. We show that the experimental variation of the
electrical conductivity with temperature follows a small-polaron model and that
the Seebeck coefficient can be explained by a temperature-dependent
Heikes-Chaikin-Beni model. The thermoelectric figure-of-merit ZT of this
nanoceramic material reaches 0.3 at 1076 K.
