EXAFS study of NiAl in thin films

Technologically important coatings of transition-metal aluminides can be pr oduced by thermal or ion beam mixing of multilayer structures sputter depos ited on substrates. The quantitative detection of constituents by depth pro filing is sufficient to establish the efficiency of mixing methods. However , to decide whether a mixture of nanoparticles or a stoichiometric alloy is formed, EXAFS analysis of the local atomic neighborhood in the film is req uired. Ni K edge EXAFS spectra are measured on a series of samples of Ni/Al multilayer on Si(111) surface, after ion mixing at different substrate tem peratures. The spectra show that with increasing temperature the nickel alu minide phase gradually substitutes the Ni fcc metal phase.