Kim J J, Bishop S R, Thompson N J, et al. Investigation of nonstoichiometry in oxide thin films by simultaneous in situ optical absorption and chemical capacitance measurements: Pr-doped ceria, a case study[J]. Chemistry of Materials, 2014, 26(3): 1374-1379.

ABSTRACT

Fast oxygen incorporation, essential for low temperature SOFCs, is enhanced in mixed ionic electronic conducting electrodes. In this study, simultaneous in situ measurement of transient optical absorption changes and electrode impedance is demonstrated as a powerful and convenient means for examining oxygen exchange kinetics in oxide thin films, utilizing Pr0.1Ce0.9O2-$\delta$ as a model system. Absorption in the visible spectrum is tied to the fraction of Pr in its oxidized state (4+), which in turn is related to the material's oxygen deficiency. The origin of discrepancies between kchem derived from optical relaxation measurements and kelec from electrochemical measurements is discussed in terms of surface contamination and the potential catalytic effect of metal contacts.