High-temperature thermoelectric properties of In2O3-based mixed oxides and their applicability to thermoelectric power generation

Abstract

Thethermoelectric properties of mixed oxides In₂O₃·MO_x(MO_x= Cr₂O₃, Mn₂O₃, NiO, ZnO, Y₂O₃, Nb₂O₅ SnO₂) are investigated in terms of the thermoelectric materials at high temperature. The Seebeck coefficients,S, of all the samples have negative values, and those of In₂O₃·SnO₂ and In₂O₃·ZnO increase linearly with temperature, attaining values of –90 and –210 µV K^–1 at 1000 °C, respectively. The electrical conductivities, σ, of these oxides are significantly high. The power factor S²σ of the oxides has constantly positive temperature coefficients up to over 1000 °C. Rather low thermal conductivities, κ, of the sintered bodies of the oxides,ca. 1.7 W m^–1 K^–1 at room temperature, lead to the largest value of the thermoelectric figure of merit Z= 0.4 × 10^–4 K^–1 for M = Sn at 1000 °C, and the Z value increases toward higher temperatures.