STUDIES OF CHEMICAL DIFFUSION IN LA1-XSRXCO3-DELTA

Chemical diffusion in La1-xSrxCoO3-delta with x = 0.3 and 0.6 has been studied by transient thermogravimetry in the temperature range 620-11 00 degrees C and at oxygen partial pressures from 1 to 1.6 . 10(-4) ar m. In view of the defect structure of La1-xSrxCoO3-delta the chemical diffusion is concluded to reflect diffusional transport of oxygen vaca ncies. The transient kinetics indicate that the chemical diffusion com prises one diffusion process at near-atmospheric oxygen pressures and two diffusion processes at reduced oxygen pressures. This behaviour ma y reflect that microdomains of ordered structures are formed as the ox ygen vacancy concentration increases with decreasing oxygen activity/o xygen deficiency.