Thermal conductivity of AxBO2-type layered oxides Na0.77MnO2 and LiCoO2

We prepared polycrystalline samples of the A(x)BO(2)-type layered oxides Na0.77MnO2 and LiCoO2, and measured thermal conductivity (kappa) from 15 to 280 K. Na0.77MnO2 shows a low kappa of 15 mW/cmK at 280 K. while LiCoO2 shows a much higher K of 40 mW/cmK at 280 K. By comparing these results with kappa of NaCo2O4, we found that the low kappa of A(x)BO(2) essentially comes from the A-ion deficiency, not from the layered structure itself. The present studs reveals that the lattice proper-ties of the layered oxides are essentially three-dimensional, although the electronic states are often highly two-dimensional.