Maria C. Militello

Elemental Palladium by XPS

X-ray photoelectron spectroscopy (XPS) spectra of elemental palladium (Pd) are presented. The specimen is a polycrystalline foil and was analyzed after chemical cleaning and ion-sputtering to remove surface contamination. The spectra were collected with a Surface Science Instruments SSX-101 M-Probe ESCA instrument using monochromatized Al Kα x rays. Spectra include a survey scan and the Pd 3d, 3p, 3s, 4s, 4p, and valence band regions. Also included are the Pd MNN and MNV Auger transitions.

Vapor deposited thin gold coatings for high temperature electrical contacts

Using electron beam evaporation, thin films of Au over Ni and Au over Pd/sub 80/Ni/sub 20/ have been deposited on stainless steel and copper alloy substrates for high temperature electrical contact studies. The structure and composition of the films were studied in detail using electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS) with sputter depth profiling. The contact properties, such as contact resistance, fretting wear resistance, and thermal stability have been measured. The Ni and Pd/sub 80/Ni/sub 20/ layers of about 200 to 300 nm thickness have been shown to be effective in maintaining high temperature stability up to 340/spl deg/C in air by blocking the diffusion of elements in the substrates to the Au surface. These coatings also show good fretting wear resistance. These desired properties have been achieved with the thickness of the Au, Ni, and Pd/sub 80/Ni/sub 20/ layers substantially less than that of the conventional electroplated coatings.

A diamond-like carbon film for wear protection of steel

Abstract We have deposited diamond-like carbon (DLC) and amorphous SiN films on a tool steel coupon. In order to make the DLC adhere to the metal, we used an interlayer of amorphous SiN, taking advantage of the fact that the SiN coating adheres to the metal and the DLC adheres to the SiN. The DLC/SiN-coated substrate showed a significant reduction in friction compared with either uncoated or SiN-coated substrates in our laboratory bench tester after lubricated sliding for 30 h. In addition, on the basis of surface profilometry analysis, the DLC/SiN-coated plate showed less wear and a much smoother surface. The films were analyzed using X-ray photoelectron spectroscopy and sputter depth profiling. Our results suggest that DLC is a promising coating for wear protection.

Palladium Chloride (PdCl2) by XPS

X-ray photoelectron spectroscopy (XPS) spectra of palladium chloride (PdCl2) are presented. Ground PdCl2 powder was pressed into Al foil and analyzed with a Surface Science Instruments SSX-101 M-Probe ESCA instrument using monochromatized Al Kα x rays. Spectra include a survey scan, the Pd 3d, 3p, 3s, 4s, 4p regions, the Cl 2p, 2s, and valence band regions, and the Pd MNN and MNV Auger transitions.

Characterization of surface modified α-iron by nitrogen plasma immersion ion implantation: a microstructural study

Abstract This paper discusses the morphology of pure iron surfaces modified by nitrogen plasma immersion ion implantation and compares them to similar surfaces treated with conventional plasma nitriding. Analysis of the samples was performed with glancing angle X-ray diffraction and traditional Bragg–Brentano geometry X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and depth profiling using X-ray photoelectron spectroscopy in combination with sputtering. The structures formed both by thermal nitriding and plasma ion implantation correlate very well with the Fe–N phase diagram, as the surface temperature and nitrogen concentration are decisive factors in developing specific crystalline phases. Only at lower temperatures, where chemical absorption and thermal diffusion effects are strongly limited, does the distribution of implanted nitrogen become substantially of the non-equilibrium type, and can almost be freely tailored. At low temperatures, however, the nitrided layer becomes extremely shallow (defined almost solely by the ballistic ion model), thereby limiting the applicability of this technology for iron-based materials. Hence, unless specific ferrous alloy materials are chosen which promote nitride formation and diffusion, e.g. chromium and iron-chromium alloys, the niche for nitrogen plasma ion implantation into ferrous materials seems to be limited to those cases where surface nitriding is desired, but where exposure of the workpiece to high temperature is forbidden.

A comparison between high- and low-energy ion mixing at different temperatures

Abstract High-energy ion mixing occurs when an ion beam of a few hundred keV bombards an interface under the surface. Low-energy ion mixing arises when an ion beam of a few keV bombards an interface near the surface during, e.g., sputter depth profiling and low-energy ion-assisted deposition. At low temperatures, the rate of both high- and low-energy ion mixing can be influenced by thermodynamic parameters, such as the heat of mixing and the cohesive energy of solids. These effects are demonstrated by ion mixing experiments using metallic bilayers consisting of high-atomic-number elements. A model of diffusion in thermal spikes is used to explain this similarity. Low-energy ion mixing can also be strongly affected by surface diffusion and the morphological stability of thin films. These effects are illustrated using results obtained from sputter depth profiling of Ag/Ni, Ag/Fe, and Ag/Ti bilayers at elevated temperatures. High-energy ion mixing at low temperatures can be influenced by the anisotropic momentum distribution in a collision cascade as seen from a set of marker experiments to determine the dominant moving species in high-energy ion mixing. An understanding of these similarities and differences between high- and low-energy ion mixing at different temperatures will provide useful guidelines for applications of ion mixing.

Manganese Dioxide (MnO2) by XPS

XPS spectra of manganese dioxide (MnO2) powder are presented. The spectra were collected using monochromated Al Kα x-rays. Spectra include survey scan, the Mn 2p, 3p, and 3s regions, the O 1s region, and the Mn LMM Auger transitions.

The effects of elevated temperature on sputter depth profiles of silver/nickel bilayers

The effect of elevated temperature on the sputtering behavior of silver/nickel bilayers was studied using Auger electron spectroscopy and argon ion sputtering while specimens were held at elevated temperatures (25, 135, 235, 335, and 435 °C). We find that the silver overlayer tranforms from a layer to islands during ion sputtering at temperatures above 100 °C. The transformation to islands is thought to relieve film stresses caused by film‐growth and/or lattice mismatch. Surface diffusion of silver is also observed at elevated temperature (>100 °C). This causes the lower surface energy metal (Ag) to cover the higher surface energy metal (Ni) in regions between the islands. These experiments show that properties of the system such as the heat of mixing, and the surface and interface energies need to be considered when the sputter depth profiling technique is used to study thin film structures, particularly when sputtering is performed at elevated temperatures.

Graphite-Filled Poly(vinylidene fluoride) (PVdF) by XPS

XPS spectra of graphite-filled poly(vinylidene fluoride) (PVdF) are presented. The specimen consists of 17 wt % PVdF and 83 wt % graphite. A freshly cut surface was examined using monochromated Al Kα x-rays. Spectra include a survey scan, C 1s and F 1s regions, and the F KLL Auger transitions.

Lithium Manganese Oxide (LiMn2O4) by XPS

XPS spectra of lithium manganese oxide (LiMn2O4) are presented. The spectra were collected using monochomated Al Kα x-rays. Spectra include survey scan, the Li 1s region, the Mn 2p, 3p, and 3s regions, the O 1s region, and the Mn LMM Auger transitions.