SURFACE SEGREGATION OF NIZR

The preferentially sputtered surface of a clean polycrystalline NiZr s ample has been studied with X-ray photoelectron spectroscopy (XPS), Au ger electron spectroscopy (AES) and low energy ion scattering (LEIS). The depth profile of the constituents has been determined by AES measu rements taken at two significantly different electron energies which h ave different escape depths. Similarly the composition has been determ ined with XPS on both the clean surface and on surfaces contaminated w ith a small amount of oxygen. The composition of the outermost layer h as been determined by the use of LEIS at several incident energies usi ng Ar+. In the LEIS analysis the effect of charge exchange has been es timated by a novel measurement of the charge exchange parameters while simultaneously determining the relative concentrations of Ni and Zr. The results of the different approaches and the complementary informat ion obtained will be described. The composition of the clean annealed surface, measured with AES only, will be contrasted with the surface c oncentration of the preferentially sputtered surface.