Proton diffusion in the superprotonic phase of CsHSO4 studied by 1H NMR relaxation

Proton dynamics in phase I of CsHSO4 have been studied by means of 1H spin-lattice relaxation. From the analysis of the relaxation times, mean residence times of protons are estimated. Translational diffusion of protons takes place with parameters of Ea=35 kJ/mol and τ0=1.7×10−13 s. The proton mean residence time changes from 3.0×10−9 to 1.3×10−9 s in the temperature range from 430 to 470 K. These parameters can well explain the macroscopic electric conductivity. The proton transfer between two SO4 tetrahedra along a hydrogen bond is fast enough and the proton transport is limited by the SO4 reorientation in a similar manner to phase II.