Tracer Diffusion Coefficient of Oxide Ions in LaFeO3 by SIMS Measurement

Oxygen has no radioactive isotope suitable for use as a tracer in diffusion experiments. Therefore, the gas-solid isotopic exchange technique using the stable isotope 18O has been used for the measurements of the tracer diffusion coefficients of oxide ions in oxide materials. So far, the gas phase analysis has been mainly adopted, in which the decrease of the 180 concentration in the atmosphere is measured. In this method, the numerical analysis of the data is very complicated when the surface reaction rate is low [1]. Moreover, a painstaking and highly skillful experiment must be performed, especially for the compounds with low oxide ion diffusivity [2]. The depth profile measurement has an advantage that the diffusion profile in solids is directly determined. It is also easily applied for the compounds with low oxide ion diffusivity, because the penetration length in the order of micrometer is adequate for this method.