The solid state reaction in multilayers studied by X-ray absorption spectroscopy

Abstract

We present here some applications of X-ray absorption spectroscopy (XAS) to the study of the solid state reaction in multilayers. A brief account is given of two multilayer systems that we have investigated using this technique (Nd/Fe and Co/Sn). Then we describe in more detail the solid state reaction in Ce/Ni multilayers. The dynamics of diffusion is followed in this case by measuring X-ray absorption at the Ce L III edge and the Ni K edge. Valence instabilities render this technique highly sensitive to the change in local environment accompanying diffusion. Two models of diffusion (the simple Fick model and the homogeneous amorphous interlayer model) are studied and we show that XAS allows us to follow the evolution of the concentration profile as a function of time and temperature consistent with each model. Then nickel extended X-ray absorption fine structure is used to select the more realistic model.