Showing papers by "Tery L. Barr published in 1997"

ESCA studies of the coordination state of aluminium in oxide environments

Abstract: X-Ray photoelectron spectroscopy (known as XPS or ESCA) can differentiate between tetrahedral and octahedral Al atoms in inorganic solids. Although primarily used for the study of aluminosilicates, this semi-quantitative technique is applicable to other materials, irrespective of whether they contain aluminium in one or more coordinations with respect to oxygen. If less sensitive to the coordination of Al, the range of ESCA, a surface-oriented technique, is thus not very different from that of the bulk-oriented solid-state NMR. The procedures described here are successful with any high-resolution ESCA system, but are greatly facilitated by flood gun technology which removes insulator-induced charging shifts. Areas of potential difficulty are also discussed.

X-ray photoelectron spectroscopy study of the chemical interaction between BN and Ti/TiN

Abstract: Many nitrides, particularly BN and TiN, have stimulated commercial interest because of their extreme hardness, wear and corrosion resistance, and thermal and electrical properties. All of these features are enhanced by the resulting structures and the large degree of covalency exhibited by the metal–nitride bonds. Coatings of select nitrides with films of related materials may particularly influence these properties in critical surface and interface regions. Materials of interest include the deposition by plasma vapor deposition of Ti and TiN on BN substrates. Some of these systems were then subjected to varying degrees of physical and thermal alteration. Resulting structural and morphological features have been investigated with electron microscopy and x-ray diffraction. Critical importance is also attributed to the chemical behavior of species deposited and grown at the resulting interfaces. Detailed x-ray photoelectron spectroscopy has, therefore, been rendered of these interfaces using cross-sectional...

Characterization of chemical interaction of asbestos surfaces during culturing with lung cells

Abstract: The pathogenic nature of asbestos has become an established fact in environmental science. This is particularly true for the injury of epithelial cells. Although speculation exists as to the involvement of the fibrous nature of asbestos silicates, and/or the adverse oxidative properties of any ferrous components, as of yet, no concrete mechanism has been discerned for this pathogenic interaction. It should be apparent, however, that since the silicates are apparently altering the chemical and structural properties of the cells, stoichiometry requires some type of corresponding chemical alteration in the properties of the asbestoses. In the present case, we report on a variety of interesting results centered around the latter “reverse mechanism.” In these studies, x-ray photoelectron spectroscopy or electron speetroscopy for chemical analysis, atomic absorption spectroscopy, and electron spin resonance were employed to track the behavior and alterations of the chrysotile silicates immersed in select cell c...