The use of superlattices to probe and control reactions at buried interfaces

Abstract

Little is known about the initial stages of solid state reactions, owing in part to the lack of suitable experimental probes for buried interfaces. We have taken advantage of the unique properties of multilayer composites to investigate the evolution of buried interfaces as a function of temperature and time. The high density of interfaces within the multilayer composite permits the thermochemistry of interfacial reactions to be followed using calorimetry. In addition, the regular composition variations within a superlattice result in Bragg reflections. Relative intensities of these reflections are determined by the composition variation across the interface. Development of interfacial structure during interdiffusion can be monitored by following the changes in the intensities of these Bragg reflections as a function of temperature and time. The sensitivity of this technique permits the intial stages of solid state reactions to be followed. We present a mechanism for the initial stages of solid state reactions.