Thermoelectric properties of solution combustion synthesized Al-doped ZnO

Abstract

Thermoelectric properties of Al-doped ZnO prepared by solution combustion synthesis using urea as fuel and sintered by spark plasma sintering were investigated for developing an energy- and time-saving synthesis method to decrease its thermal conductivity without a significant deterioration in other thermoelectric properties. The desired materials were successfully synthesized and sintered. The thermoelectric properties of the synthesized products subjected to planetary ball milling (PBM) treatment before sintering were compared with those of synthesized products not subjected to PBM treatment; the results showed that the former products had a larger power factor and higher thermal conductivity than the latter products. The thermal conductivity of all as-synthesized products was in the range of 8.3-19.7 W·m -1 ·K -1 at room temperature, which was significantly lower than that of the products synthesized by a conventional solid-state reaction method. (Zn 0.99Al 0.01)O obtained by PBM had the highest dimensionless figure of merit ZT of 0.050 at 863 K. From these results, it is inferred that solution combustion synthesis is an effective method for synthesizing Al-doped ZnO with relatively low thermal conductivity for high-temperature thermoelectric applications. © 2008 The Japan Institute of Metals.