Oxide-Ion Diffusivity in Fluorite and Perovskite Oxides for Inert Anode in Molten Salts and their Characterization

Abstract

This study characterizes the oxide-ion diffusivities of fluorite and perovskite oxides for an inert anode in molten salts below intermediate temperatures (∼800 K) and investigates the morphologies of nanoparticles used for nanostructure-fabricating the inert anode to optimize the oxide-ion diffusivity using phonon vibration. The isotropic phonon vibration of each material was estimated using high-temperature X-ray diffraction measurements. Both fluorites and perovskites exhibited a tendency for high oxide-ion diffusivity, as confirmed at a high-vibrational, oxide-ion frequency. Crystal anisotropy measurements of phonon vibration indicated that the oxide ions diffuse isotropically and three-dimensionally in each crystallographic face of fluorites while they diffuse preferentially along the (a, b) plane in perovskites. These results suggest that the oxide-ion diffusivity was improved using spherical fluorite nanoparticles and curtailed using layered perovskite particles.