Proton diffusivity in spark plasma sintered BaCe0.8Y0.2O3 − δ: In-situ combination of quasi-elastic neutron scattering and impedance spectroscopy

The thermal activation of proton conductivity metal-oxide based ceramics is typically studied with electrochemical impedance spectroscopy (EIS), particularly in the context of solid electrolyte material research. To a lesser extent quasi-elastic neutron scattering (QENS) is applied for the same purpose. The latter probes the proton dynamics at the molecular scale. We have designed a simple in-situ cell which allows collecting EIS and QENS spectra on the same ceramic sample at high temperatures, and we present QENS plus EIS data collected in-situ and operando on the ceramic proton conductor BaCe0.8Y0.2O3 − δ from 300 K to 800 K. The diffusion coefficient and average proton jumping length are derived from the temperature dependent measurement to study the activation processes and near neighborhood interactions for proton conductivity. The proton jump lengths coincide with the mean distance between the O2–O2 and O3–O3 oxygen ions and indicate proton inter-octahedra transfer.