Ionic defects are critical to the properties of functional oxides, governing mixed ionic and electronic conductivity, surface kinetics and reactivity, as well as lattice expansion and dynamics. These properties underpin applications in energy (e.g., fuel cells, electrocatalysts) and information technologies (e.g., memristors, neuromorphic computing). 

In this talk, Westlake University’s Qiyang Lu covers three fronts of harnessing ionic defects for tailored oxide thin film properties. First, to accurately predict the electrochemical driving force needed to manipulate ionic defects for designed properties, constructing phase diagrams that correlate physical properties (conductivity, chemical diffusivity, lattice constant, etc.) with ionic defect concentration is essential. However, such tasks often require a large number of samples and can be susceptible to artifacts introduced by sample-to-sample variations. To address this challenge, the group developed a new electrochemical device that can introduce spatially graded ionic defect concentrations in a single oxide thin film sample. Combined with high-spatial-resolution characterization tools, this approach enables high-throughput construction of phase diagrams controlled by ionic defect concentration.