Oxidation studies of yttrium implanted copper, molybdenum and tantalum using high-energy resonant helium backscattering

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Department of Physics


The 16O(α,α)16O resonance at 8.8 MeV was used to determine the oxidation rates of Y implanted Cu, Mo and Ta. At back angles this resonance has a uniform cross section of ≈ 25 times the Coulomb cross section over an energy range of ≈ 0.6 MeV, allowing the surface oxidation of metals to be easily determined without the necessity of weighing the samples. Oxidations were made at 200, 400 and 500° C for Cu, Mo and Ta, respectively and for times ranging from 10 min to 10 h. At short times the oxidation is enhanced in the Y implanted materials as compared to unimplanted materials. However, as the oxidation times increase the oxidation rate in the implanted materials falls, and in the case of Cu and Ta the total amount of oxygen in the implanted samples eventually becomes lower than that of the unimplanted samples. In all cases Y implantation strongly effects the oxidation process. For Ta and Cu retardation of grain boundary oxidation occurs. For Mo, implantation produces a discrete oxide layer which grows in a layer-by-layer manner. These data indicate that the YCu and the YTa oxides are more passivating than their unimplanted counterparts.

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Nuclear Inst. and Methods in Physics Research, B