Visualization and quantification of ionic defect flow by electrocoloration

Abstract

In this research, we explore electrocoloration experiments as an easily accessible and non-destructive technique for visualizing and quantifying ionic defect flows in oxide thin films, with a specific focus on calcium-doped bismuth ferrite (Ca-doped BiFeO3, or BCFO) as the model material. This study utilizes the observation of color transitions induced by electrical bias to elucidate the dynamics of ionic migration and defect behaviors in these materials. To augment the insights gained from electrocoloration, we integrate traditional methodologies such as electrochemical impedance spectroscopy, thereby enriching our comprehension of these phenomena and corroborating our experimental results. Our investigations disclose fascinating phenomena, notably filamentary conduction and the kinetic roughening of color fronts. Consequently, electrocoloration emerges as a promising investigative tool for examining ionic migration in oxide-based materials, with potential implications for enhancing technologies in fields such as resistive random access memory and solid oxide fuel cells.