Electrical and thermal transport properties in layer-structured (ZnO)mIn2O3 (m=5 and 9) ceramics

The electrical and thermal transport properties are characterized for layer-structured (ZnO)(m)In2O3 (m = 5 and 9) (Z(m)IO) ceramics of near theoretical densities. The results of the low temperature Hall effect study suggested that the InO2- layers, which have oxygen defects, determine the carrier scattering mechanism of the material, and explain the previously demonstrated two-dimensional character of the carrier transport behavior. From an adaptation of the Wiedemann-Franz law, the lattice thermal conductivity (kappa(L)) of Z(m)IOs at 300 K is estimated to be similar to2.6 W/mK; this value is nearly one fifteenth of that for Al-doped ZnO ceramics (similar to40 W/mK). These results suggest that the two-dimensional structure consisting of the InZnmOm+1+ and InO2- sub-lattices, gives rise to the strong electrical anisotropy and the low kappa(L) which is attributed to the reduced mean free path, of the phonon, similar to artificial super-lattice materials.