High-temperature thermoelectric properties of (Zn1− x Al x )O

A mixed oxide (Zn1−xAlx)O exhibits promising thermoelectric properties attaining a dimensionless figure of merit ZT of 0.30 at 1000 °C, which value is much superior to other oxides and quite comparable to conventional state-of-the-art thermoelectric materials. The addition of a small amount of Al2O3 to ZnO results in a large power factor of 10–15×10−4 W/mK2, showing a marked increase in the electrical conductivity while retaining moderate thermoelectric power. A large product of the carrier mobility and density of states would be responsible for the favorable electrical properties of the present oxide. A figure of merit Z=0.24×10−3 K−1 is attained by (Zn0.98Al0.02)O at 1000 °C, even with a high thermal conductivity. A predominant proportion of the phonon thermal conductivity promises a further improvement in the thermoelectric performance by selective enhancement of phonon scattering.