Self-Diffusion in Chemically Homogeneous Multilayers Using Neutron and Nuclear Resonance Reflectivity

Abstract

ABSTRACTNeutron reflectivity is a well-established technique for studying self-diffusion in chemically homogeneous system as neutron scattering lengths are different for isotopes of an element. For x-ray there is no contrast for a multilayer with isotopic abundance. However, placing Mössbauer active nuclei in a chemically homogeneous system, self-diffusion of the constituents can be probed using nuclear resonance scattering of Mössbauer active nuclei. In the present work, we have applied the neutron reflectivity technique for studying the self-diffusion of iron and nitrogen in nano crystalline multilayers of FeN/57FeN and FeN/Fe15N and nuclear resonance reflectivity techniques for studying iron self diffusion in FeNZr/57FeNZr. Both the techniques are complementary to each other and give a unique depth resolution of the order of 0.1 nm. As compared with conventional techniques used for probing self-diffusion, neutron and nuclear resonance reflectivity techniques can be applied at significantly lower temperatures. On the basis of the obtained results the diffusion mechanism in chemically homogeneous multilayers is discussed in the present work.