Interphase exchange and diffusion of oxygen in lanthanum-strontium cobaltites doped with iron

摘要

Oxides La_(0.4)Sr_(0.6)Co_(1-x)Fe_xO _3-δ (x = 0.2 and 0.4) were synthesized by the ceramic technology. The kinetics of exchange and diffusion of oxygen in these oxides were studied by the isotopic exchange method over the temperature range 600-900°C at an oxygen pressure of 10 torr. The temperature dependences of interphase exchange rate and oxygen diffusion coefficient in the bulk and near-surface region were obtained, and the effective activation energies of exchange and oxygen diffusion were calculated. The concentration of iron ions was shown to have no substantial influence on the exchange rate and oxygen diffusion. Ratio between the values of exchange rate and diffusion coefficient were shown to influent on the precision of the values estimation.