Oxygen isotope exchange with a dense La_(0.6)Sr_(0.4)CoO_(3-δ) electrode on a Ce_(0.9)Ca_(0.1)O_(1.9) electrolyte

摘要

Oxygen isotope exchange experiments were carried out with a dense La_(0.6)Sr_(0.4)CoO_(3-δ) film (0.5 µm thick) deposited on a Ce_(0.9)Ca_(0.1)O_(1.9) substrate by a laser ablation method. The isotope exchange profile was measured from the surface into the electrolyte by a secondary ion mass spectrometer (SIMS). The oxygen diffusion through the La_(0.6)Sr_(0.4)CoO_(3δ) film was fast enough not to make any observable gradient in oxygen isotope concentration inside the film. The surface isotope exchange rate, k*, was calculated from the diffusion profile into the electrolyte layer. The electrochemical impedance, σ_E, was compared with k*. The oxygen partial pressure dependence of those two parameters were quite similar. The absolute value of k* was larger than expected from σ_E by a factor of 2 or higher.