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.