Proton Diffusion in Strontium Cerate Ceramics studied by Quasielastic Neutron Scattering and Impedance Spectroscopy

Abstract

Abstract Perovskite structured strontium cerate doped with ytterbium and water, e.g. SrCe 0.95 Yb 0.05 H 0.02 O 2.985 , is a well known proton conductor at elevated temperatures. We have studied its proton conductivity or diffusivity, respectively, by impedance spectroscopy, IS, and by quasielastic neutron scattering, QENS. While the former method yields a macroscopic proton diffusion coefficient, the latter method allows to elucidate the microscopic proton diffusion mechanism. It consists of a sequence of free diffusion and trapping/escape events with the Yb 3+ ions acting as trapping centers. The self-diffusion coefficient obtained with QENS agrees with the conductivity diffusion coefficient obtained with IS.