Anhydrous solid protonic conductors

We have included in this category hydronium salts such as H O CIO. or p-alumina in which all water molecules are protonated. 

From these preliminary results it is clear that future studies have to overcome several problems. 

Precise structural work is needed to correlate the jump lengths deduced from QNS with possible crystallographic sites for the proton. Two different sets of data have, for example, been published on the CSHSO4 superionic phase and a third, more precise neutron diffraction study on CSDSO4 has appeared . The modelling of the oxygen and proton positions is indeed a difficult task in these highly disordered materials. 

The halfwidth of the fitted lorentzians is reported in Fig. 21.1c (black circles) as a function of momentum transfer. The solid line a corresponds to a fitted at small Q values. 

The dashed curves correspond to the Chudley-Elliott model with L = 1.5 (line b) and 1.8 A (line d) and the dolled curve to the Random Jump Diffusion model with = q.93 (line c) and 1.22 A (line e). 

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Donoso P, Gorecki W, Berthier C et al (1988) NMR, conductivity and neutron scattering investigation of ionic dynamics in the anhydrous polymer protonic conductor PE0(H3P04)x. Solid State Ionics 28 969-974... 

Hydrophilic polymers such as poly (vinyl alcohol) or polyoxyethylene can be impregnated with a mineral acid and behave as solid proton conductors [119]. Several researchers [120] showed that polyethylenimine-sulfuric acid and phosphoric acid systems were well-behaved solid proton conductors under anhydrous conditions. Further information regarding these membranes is available in the literature [120]. Finally, Cakmak and Bicaksi [121] satisfactorily elaborated PEEK/PEI blend films. 

Fig. 3.1. Relationship between the pre-exponential factor

Incoherent neutron scattering studies of proton conductors from the anhydrous solid state to aqueous solutions... 

Table 21.1. Specific conductivity a, proton self-diffusion coefficient D, and residence time between reorientations x, for some anhydrous solid state protonic conductors... 

Kim J D and Honma I (2005) Anhydrous solid state proton conductor based on benzimidazole/monododecyl phosphate molecular hybrids. Solid State Ionics, 176, pp. 979-984. 

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