Anhydrous materials oxonium perchlorate, acid phosphates, arsenates, sulphates and selenates

Proton-containing anhydrous materials are interesting proton conductors as they are stable to relatively high temperatures and contain fewer protons that do hydrates. Their conduction mechanism is thus expected to be easier to understand, and the proton diffusion may be investigated over a rather wide temperature range. However, the conduction mechanism can become complicated when the melting temperatures of the protonic species and the non-protonic sublattice are close. 

Oxonium perchlorate H OCIO is the first solid proton conductor whose conductivity, = 3.4 x 10 cm S has been found to be com- 

130 cm due to the translational motion of cations. When the sample is hydrated forming a layer of protonated water, the spectrum is close to that of a Debye solid and a continuous distribution of modes exists. The same behaviour is observed for H30a04 (and CSHSO4) when going from the low to the high temperature phase. The P( o) function becomes similar to that of a liquid and the P(o)) value at w = 0 becomes different from zero because of the diffusion of mobile species . 

H3OCIO4 and CsHS04 - in the low and high temperature (conductivity) phases (with 

Potier and Rousselet proposed the following mechanism derived from Bjerrum there is a rotation of the H30 ion followed by proton transfer to a CIO4 anion, then a rotation of the resulting HCIO4 species and subsequently a proton transfer to H2O. Such a mechanism implies the presence of proton defects the formation of which can be expressed by two possible equilibria 

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Anhydrous materials oxonium perchlorate, acid phosphates, arsenates, sulphates and selenates... 

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