Proton conduction mechanism in n solid acidic hydrates

3 Proton conduction mechanism in n solid acidic hydrates 

For solid add hydrates in which the proton is a main constituent of the compound, n is usually smaller than ten according to an amplification 

Quantitative determination of water reorientational and diffusional modes by NMR and 0 tracer experiments on the analogous HUAs provided no correlation with the data for proton conductivity . Instead a good correlation between molecular diffusion and proton conductivity indicated a mechanism in which H2O and HjO are mobile as a whole in the conduction plane without a significant amount of proton transfer between them. The proton conductivity in HUP and HUAs is somewhat higher than that of other monovalent cations in corresponding compounds. This was one of the reasons why molecular diffusion was not 

Unfortunately HU As is the only proton-conducting hydrate for which available oxygen diffusion coefficient data allow direct verification of the vehicle mechanism. For other compounds there is just an indication that this may be the mechanism. These are e.g. diffusion bottleneck considerations for ionic conduction in zeolites or the exceptionally high temperature factors for the water oxygen in and some heteropoly- 

In general, the low thermal stability and high vapour pressure for the anticipated vehicle molecule make plausible a conduction mechanism similar to the one in acid solutions for this family of compounds. If we assume the mechanism presented above, then at least some amplification for proton conduction in the solid hydrate TSA.28H2O is observed A = 1.8) (Fig. 26.3). This is in perfect agreement with a ratio [HjO ]/ [H2O] = 6 for this compound (Fig. 31.5). A is indeed independent of temperature and appears to be a structural feature as suggested by the model. 

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