Giant Haven Ratio for Proton Transport in Sodium Hydroxide

Solid sodium hydroxide has been prepared and investigated with respect to its transport properties. The proton conductivity depends significantly on the water content. In NaOH with minimum water content (NaOH in phase equilibrium with Na2O) the proton conductivity is much lower than reported in the literature. Defect chemistry and transport characteristics are discussed. For the same dry samples pulsed field gradient NMR revealed a surprisingly high H-diffusion coefficient and thus a Haven ratio of 10–104 in the cubic phase. In fact this value is only the lower limit since the measured conductivity may still be influenced by residual extrinsic effects or due to Na+ contributions. A cooperative mechanism is described which is able to explain this anomaly.