A point defect model was used to describe the functional dependence of defect species in SrCe0.95Y0.05O3-d on H, water vapor, and O partial pressure. Concentrations of each defect were simulated with a C programming code. The mobilities of protons, O ions, and electrons were evaluated from partial conductivities. Hydrogen permeation equations derived from chemical diffusion theory were solved by a numerical modeling method. Accurate predictions of the H permeation flux were possible only when the functional dependence of ionic/electronic conductivity on both H and O partial pressure was known. The dependence of H permeation flux on H potential difference agrees with the PH2 dependence of electronic conductivity. The H permeation flux calculated for 1mm SrCe0.95Y0.05O3-d was about 1.50 x 10-9mol/cm2s under ΔPH2 (10-7 to 1atm), PO2 (10-24 to 10-12atm) with the same PH2O (0.03atm) on both sides at 973K.

Numerical Modeling of Hydrogen Permeation in Chemical Potential Gradients. S.J.Song, E.D.Wachsman, J.Rhodes, S.E.Dorris, U.Balachandran: Solid State Ionics, 2003, 164[1-2], 107-16