Dielectric properties of Na_0.7CoO₂ and of the superconducting Na_0.3CoO₂·1.3H₂O

We present dielectric properties of ceramic anhydrous Na _0.7CoO₂ and the superconducting Na_0.3CoO ₂·1.3H₂O materials. The presence of water which induces superconductivity also may increase the dielectric constant (ε) of the hydrated material. This is consistent with the predicted relationship between the high ε and the enhancement of T_c in high T _c superconductors. The anhydrous sample is porous and the transport is due to some percolation via the pores. The porosity is much higher for the hydrated material and the transport is ionic inside bulk water.