Thermal conductivity of the A_xBO₂ type layered oxides Na₀.77MnO₂ and LiCoO₂

We prepared polycrystalline samples of the A_xBO_2 type layered oxides Na_0.77MnO_2 and LiCoO_2, and measured thermal conductivity from 15 to 280 K. Na0.77MnO_2 shows a low thermal conductivity of 15 mW/cmK, while LiCoO_2 shows a much higher value of 40 mW/cmK at 280 K. By comparing them with the data of NaCo_2O_4, we have found that the low thermal conductivity of A_xBO_2 comes essentially from the A-ion deficiency, not from the layered structure itself.