Measurement of ion mobility based on a reversible migration process in solids

Ion mobility, which facilitates ion migration in lattices, not only is important for selection of solid electrolytes from a large number of candidate materials but also plays an essential role in the study of the fundamentals of ion transport in solids. In the present work, a simple approach is developed for measuring the mobility of oxygen ions in a typical solid electrolyte, lanthanum-doped ceria. Changes in the concentration of oxygen vacancies, which are equivalent to variations in oxygen ions, are recorded using integrated peak intensity ratios of Raman spectra under a reversible electric field. A model of the migration process of oxygen ions in a reversing electric field is proposed based on the experimental results. The mobility of oxygen ions is determined by analyzing the time interval between two steady states based on a simplified model. By altering the electric field, this approach is applicable to the measurement of the mobilities of different ion species.