Defect Chemistry and Transport within Dense BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_{3 − δ}(BCZYYb) Proton-Conducting Membranes

This paper uses previously published conductivity measurements as the basis for establishing thermodynamic and transport properties for BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3 − δ (BCZYYb) proton-conducting membranes. BCZYYb is mixed ionic-electronic conducting (MIEC) doped perovskite that is dominantly a proton-conducting ceramic. In addition to protons, BCZYYb permits transport of oxygen vacancies and O-site polarons. The present analysis considers the effects of immobile polaron traps. The paper reports enthalpies Δ H ° and entropies Δ S ° for the defect reactions, and defect diffusion coefficients in Arrhenius form. The paper incorporates the thermodynamic and transport properties into a Nernst–Planck model to characterize BCZYYb performance as a protonic-ceramic membrane for electrolyzer and fuel-cell applications. Especially at temperatures below 600°C, BCZYYb can achieve high faradaic efficiencies (i.e., low electronic leakage) as an electrolyzer membrane.