Abstract
The thermoelectric properties of layer-structured homologous compounds of (ZnO)mIn2O3 (m is an integer) were investigated in terms of the detailed dependence of the molar ratio of ZnO to In2O3, n (=ZnO/In2O3), and of doping, such as with Ba2+, Ca2+, Sr2+, and Sn4+, for an In site. Except for the Ba and Sr dopings, all sintered specimens with n≥3 were found to be in the phases of (ZnO)mIn2O3. The highest power factor apparently existed around n=3 while the thermal conductivity was minimum at the range from n=3.5 to 5. The Ca doping effectively reduced the thermal conductivity, resulting in a dimensionless figure of merit of 0.23 (at 1053 K) for n=3.5, which was relatively high among n-type oxides.