Experimental evidence of hydrogen–oxygen decoupled diffusion into BaZr0.6Ce0.25Y0.15O3−δ

Polarization study of Fe|BaCe0.5Zr0.3Y0.08Yb0.08Cu0.04O3-δ|Fe electrochemical cells in wet H2 atmosphere

“…In the case of measurements in oxidizing conditions, the apparent activation energy of the conductivity was calculated to be 0.55 eV in the temperature range 500e900 C. The lower value of E a in wet hydrogen could be attributed to protonic conductivity, whereas in wet air (at T > 600 C) ionic conductivity and p-type electronic conductivity contribute to the measured E a . This is in agreement with literature data showing values of E a in the range of 0.3e0.6 eV for protonic, 0.6e0.9 eV for oxygen-ionic and 0.7e1.1 eV for hole conductivity [40,41]. It should also be noted that the apparent activation energy value in the low temperature range is lower than that observed in the high temperature range regardless of the atmospheric conditions.…”

Hydration of Proton-conducting BaCe0.9Y0.1O3−δ by Decoupled Mass Transport

“…The proton concentration 6–8 and chemical diffusivity of water 9–11 in these materials, as functions of thermodynamic parameters, have been investigated for their specimens exposed to sudden changes in water vapor content because of the functionality as solid electrolyte. However, in these proton conductors some recent reports, such as the electrical conductivity relaxation measurements showing a non-monotonic two-fold relaxation behavior 12–14 and in situ optical absorption spectroscopy with impedance spectroscopy 15 , have demonstrated that in the p-type oxidizing regime the proton transport depends on the two decoupled ambipolar diffusivities of proton and hole (-) and (-) pairs. Accordingly, the decoupled mass- and charge-transport theory, which was earlier based on the chemical diffusion of water, has been successfully revised by Yoo et al .…”

Partial Conductivities and Chemical Diffusivities of Multi-Ion Transporting BaZrxCe0.85-xY0.15O3-δ(x = 0, 0.2, 0.4 and 0.6)

“…Figure 11 shows typical transient behavior of electrical conductivity of BZCY upon hydration/dehydration in log(pH 2 O/atm) = −2.51 ↔ −2.36 range at 800 • C in air. Yoo et al 30 mentioned that during hydration/dehydration at fixed pO 2 the 27,53,[63][64][65][66] and as can be seen from Figure 11, the overall ECR profile during the hydration/dehydration in BZCY is also non-monotonic with a twofold relaxation behavior. It was noticed that the non-monotonic valley becomes deeper as hole conductivity increases with Ce rich composition or as more p-type oxidizing regime is observed in a fixed composition.…”