PROTON TRANSPORT PHENOMENA IN PURE ALKALINE METAL-HYDROXIDES

The preparation of pure alkaline metal hydroxides (NaOH, KOH, RbOH, Cs OH), their proton diffusion coefficients (D-H) obtained from PFG-NMR m easurements and proton conductivities (sigma) measured by complex impe dance spectroscopy are reported for the cubic high temperature phases and melts. For nominally pure material, the measured conductivities ar e very low, but still due to impurities in terms of water content, whe reas proton diffusion is found to be very high (approximate to 10(-7) cm(2) s(-1)) and well reproducible. The unusually high Haven ratios (D -H/D-sigma) of greater than 10-1000 are suggested to be the result of a proton transport mechanism involving correlated proton transfer even ts, which are discussed in detail.