Intracrystalline Equilibrium Reaction in a Protonic Conductor
Authors: R.E. Lechner, G. Schuck und K. LangerJournal-ref: J. Phys. Soc. Jpn, 70, A (2001) Suppl. 274-276 , PDF
In quasielastic incoherent neutron scattering studies on the protonic conductor Rb3H(SeO4)2, with a dynamic range from 1 µeV to 10 meV, the details of the mechanism of long-range proton diffusion were unraveled. As a result we propose a dynamic disorder in the form of an intracrystalline chemical equilibrium reaction: alternation between the association of the monomers [HSeO4]-1 and [SeO4]2- resulting in the dimer [H(SeO4)2]3- (H-bond formation) and the dissociation of the latter into the two monomers (H-bond breaking). A ‘Trigonal asymmetric H-bond’ (TAHB) model based on the assumption of time-dependent potentials, agrees well with the measured spectra. In this paper we derive, from an analysis of the measured EISF, the proton-density distribution observed on the 10-11 s to 10-10 s time-scale, which has lead us to develop this model.
