Oxygen isotopic exchange: A useful tool for characterizing oxygen conducting oxides

Towards an Improved Understanding of Electrochemical Oxygen Exchange Reactions on Mixed Conducting Oxides

In solid oxide fuel cells or electrolysis cells with ionic and electronic conducting electrodes, the electrochemical reactions take place at the gas/solid interface of the mixed conducting electrode. This is in contrast to the situation met in aqueous electrolytes, where the reactions occur at the electrode/electrolyte interface. Thus, modified concepts are required to describe the reaction rat...

Oxygen surface exchange kinetics of SrTi(1-x)Fe(x)O(3-δ) mixed conducting oxides.

The oxygen surface exchange kinetics of mixed conducting perovskite oxides SrTi(1-x)Fe(x)O(3-δ) (x = 0, 0.01, 0.05, 0.35, 0.5) has been investigated as a function of temperature and oxygen partial pressure using the pulse-response (18)O-(16)O isotope exchange (PIE) technique. Arrhenius activation energies range from 140 kJ mol(-1) for x = 0 to 86 kJ mol(-1) for x = 0.5. Extrapolating the temper...

Determination of Oxygen Nonstoichiometry and Diffusivily in Mixed Conducting Oxides by Oxygen Coulometric Titration I. Chemical Diffusion in La085r02CoO3_5

Oxygen coulometric titration has been applied to measure chemical diffusion in La0 45r0 2CoO36 between 700 and 1000°C. The transient current response to a potentiostatic step has been transformed from the time domain to the frequency domain. The equivalent circuit used to fit the resulting impedance data contains the element that describes the finite-length diffusion of oxygen into the sample s...

Determination of Oxygen Nonstoichiometry and Diffusivily in Mixed Conducting Oxides by Oxygen Coulometric Titration II. Oxygen Nonstoichiometry and Defect Model for 1a085r02CoO3_8

The oxygen nonstoichiometry of La0 8Sr0 3CoO3 has been determined as a function of oxygen partial pressure and temperature using a high-temperature coulometric titration cell. For each measured value of the oxygen chemical potential, the oxygen nonstoichiometry is found to be nearly independent of temperature. The equilibrium partial energy and entropy associated with oxygen incorporation have ...

Oxygen Isotopic Variation of Asteroidal