Establishing Quantitative Understanding of Defect-Tuned Properties in Functional Oxides by an Electrochemically-Induced Gradient of Ionic Defect Concentration

Tuning the physical and chemical properties of functional oxides by controlling the amount of ionic point defects has been recognized as a new paradigm of designing oxides with tailored functionality. In order to enable precise tuning of properties, it is important to construct quantitative relationships between properties of interest and concentration of ionic defects, which are conventionally achieved by synthesizing and measuring a large number of samples with varying defect concentration. Compared with this conventional method, which is labor-intensive and susceptible to sample-to-sample variations, this review focuses on a high-throughput method that utilizes an electrochemically induced gradient of defect concentration in one single oxide sample. Combined with spatially resolved characterizations, this method allows establishing a quantitative property-defect concentration relationship. This review will present working principles and case studies that use this method based on graded concentration of ionic defects. Potentials and future extensions of this method will also be discussed.