Molecular motion in phases II and III of CsHSO4 by static NMR and MAS NMR

•The structural geometry of CsHSO4.•The static NMR and MAS NMR.•The high proton mobility.

To better elucidate the nature of the phase transitions and to obtain a better understanding of their molecular motion, we studied their NMR spectra, the spin-lattice relaxation time T1 in the laboratory frame, and the spin-lattice relaxation time T1ρ in the rotating frame for 1H and 133Cs in CsHSO4, by static NMR and MAS NMR, respectively. In addition, the activation energies Ea for the molecular motion of 1H and 133Cs, which were determined from the temperature dependence of the T1 and T1ρ, were compared with those from previously reported NMR data. It was found that the NMR results for CsHSO4 can have different physical properties depending on the material state.

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