It was recalled that perovskite-type cerates which were doped with Yb and H2O, such as SrCe0.95Yb0.05H0.02O2.985, were high-temperature proton conductors. Proton conductivity and diffusivity were studied here by means of impedance spectroscopy and quasi-elastic neutron scattering. It was found that, whereas the former method yielded a macroscopic proton diffusion coefficient, the latter method permitted the determination of the microscopic proton diffusion mechanism. This involved a sequence of free diffusion and trapping/escape events, with the Yb3+ ions acting as trapping centers. The self-diffusion coefficient, as obtained by means of quasi-elastic neutron scattering agreed with the conductivity coefficient, as obtained by means of impedance spectroscopy.

C.Karmonik, R.Hempelmann, T.Matzke, T.Springer: Zeitschrift für Naturforschung, 1995, 50a[6], 539-48