Model-based characterization of charged-defect transport and apparent gas-phase permeation in mixed-conducting perovskite membranes

• Numerical model investigating multi-species permeative transport.
• Reduction of underlying assumptions produces a more general model.
• Model predicts conditions necessary for unusual effects like “uphill” diffusion.
• A vast number of experimental conditions can be quickly analyzed graphically.

A computational approach is implemented to characterize multicomponent charged-defect transport and apparent gas-phase permeation associated with proton-conducting perovskite membranes across a very wide range of gas-phase environments. The Nernst–Planck–Poisson (NPP) model predicts charged-defect and electrostatic-potential profiles within the membrane as well as apparent gas-phase fluxes entering and leaving the membrane surfaces. Results are represented as two-dimensional contour maps, enabling the large amounts of information to be presented in a compact graphical format. The results provide qualitative and quantitative insights about membrane permeation phenomena as functions of gas-phase environments across the membrane. Although the study considers the properties of a particular yttria-doped barium zirconate (BZY20), the modeling approach and qualitative insights are more widely applicable to classes of similar materials.