Oxygen-ion transport in a dual-phase scandia-yttria-stabilized zirconia solid electrolyte: a molecular dynamics...

A molecular dynamics (MD) simulation is adopted to investigate oxygen-ion diffusion mechanisms in dual-phase (cubic/monoclinic phase) zirconia-based solid electrolytes. XRD analysis is performed to validate the phase structure composition after an MD duration of 500 ps. The radial distribution function of the ion pairs is used to analyze the microstructure and mobility of the oxygen ions inside the electrolyte. The mean-squared displacement, displacement distribution, and moving path of oxygen ions indicate that ion mobility increases with Sc(2)O(3) content. Furthermore, the mobility of oxygen ions is relatively lower in the dual-phase solid-electrolyte models than in the pure cubic models. This is due to their intrinsically unfavorable configuration for ion penetration. Comparison of the diffusion coefficient and ionic conductivity of the oxygen ions in various phase compositions shows an obvious effect of phase composition complexity in the systems with high Sc(2)O(3) concentration. The introduction of the dual-phase composition concept for the MD simulation of oxygen-ion conduction behavior is a promising approach to obtaining a more realistic understanding of ion transport in a solid electrolyte.