Effects of Atmosphere Upon SIMS Analysis of Oxygen Isotopes in Oxides and Accurate Determination of Tracer Diffusivity of Oxygen

SIMS has been extensively applied to evaluating the tracer diffusivities of oxygen for many metal oxides[l–3]. This is based on the view that the oxygen isotope ratio in oxides is safely represented by the SIMS-peak intensity of the isotope without significant deviation. However, we have found that residual oxygen in the gas phase plays an interfering role in the SIMS analysis of oxygen isotope concentration, the effects of which are strongly dependent on the nature of bond between oxygen and metal atoms. This fact might lead to an unfavorable influence on determining the tracer diffusivities of oxygen, since the previous method using the gas-oxide exchange reaction requires the absolute values of oxygen concentration in bulk and at surface.