XPS AND AUGER-SPECTROSCOPY STUDIES ON MIXTURES OF THE OXIDES SIO2, AL2O3, FE2O3, AND CR2O3

X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger spectroscopy were utilized to examine qualitative and quantitative aspects involved in the surface analysis of mechanical mixtures of the title oxides. Consideration of 01s and OKVV bands of the mixtures makes it possible to distinguish between the single oxide components. The energy shift between the Fe,O, and SiO, (or Al,O,) components is about twice as large in the OKVV region as in the 01s region. By way of contrast, Auger spectroscopy analysis of the mixtures does not appear to enable a quantitative distinction between the constituent oxides to be made. Conversely, XPS analysis provides instead quantitative results, although these are affected by a relative error of f 10%. A simple approach, based on intensity ratio measurements of the single 01s components, enables relatively accurate quantitative results to be obtained. It is shown that analysis of appropriate mixtures is a useful case study for investigations on surface and interface properties of real materials. Argon ion etching effects on the mixtures and on the title oxides analyzed separately are reported.