Charge and Mass Transport Properties of BaCe0.45Zr0.4Y0.15O3-δ

Abstract

BaCe0.45Zr0.4Y0.15O3-δ (BCZY4015) was synthesized by a solid state reaction method and its charge and mass transport properties were analyzed. The solutions of analytical defect equations were obtained in terms of various defect concentrations to calculate the partial conductivity of various charge carriers. The calculation of partial conductivities showed that p-type conduction dominated the overall conductivity of BCZY4015 across the entire 700–850°C temperature range. The electrical conductivity was monitored by 4-probe dc-conductivity measurement with respect to the changes in oxygen partial pressure (pO2) and water vapor pressure (pH2O) at different temperatures. The electrical conductivity relaxation during oxidation/reduction in −2.25 ≤ log(pO2/atm) ≤ −0.65 range at a fixed pH2O, and during hydration/dehydration in air in −3.15 ≤ log(pH2O/atm) ≤ −2.35 range was recorded, and the surface exchange coefficients and chemical diffusivities of oxygen and hydrogen were calculated from Fick's second law by nonlinear least squares fitting of the conductivity data, as proposed by Yoo et al. [H. I. Yoo, J. Y. Yoon, J. S. Ha, and C. E. Lee, Phys. Chem. Chem. Phys. 10 (2008) 974–982.].