Thermoelectric characteristics of homologous compounds with layer structures in the ZnO-In2O3 system

Thermoelectric materials with high Z's have been searched for recently among semiconducting oxide ceramics for the purpose of power generation at high temperatures in an air atmosphere. Metallic oxides consisting of non-transition metal elements which mould possibly have large band widths and high carrier mobility have been the target materials. One possible oxide group is that having In/sub 2/O/sub 3/ as a main component. In the present study, homologous compounds of (ZnO)mIn/sub 2/O/sub 3/ (m=integer) with layer structures were synthesized by reaction-sintering the powder mixtures of ZnO and In/sub 2/O/sub 3/ at 1823 K for 2 h in air. Their thermoelectric characteristics, i.e. electrical conductivity, Seebeck coefficient, and thermal conductivity were measured at 500-1000 K. Their Z depended on the composition and the microstructure.