title: Quantification problems in depth profiling of pwr steels using Ar+ ion sputtering and XPS analysis.
abstract: The oxide scales of AISI 304 formed in boric acid solutions at 300 degrees C and pH = 4.5 have been studied using X-ray photoelectron spectroscopy (XPS) depth profiling. The present focus is depth profile quantification both in depth and chemical composition on a molecular level. The roughness of the samples is studied by atomic force microscopy before and after sputtering, and the erosion rate is determined by measuring the crater depth with a surface profilometer and vertical scanning interferometry. The resulting roughness (20-30 nm), being an order of magnitude lower than the crater depth (0.2-0.5 microm), allows layer-by-layer profiling, although the ion-induced effects result in an uncertainty of the depth calibration of a factor of 2. The XPS spectrum deconvolution and data evaluation applying target factor analysis allows chemical speciation on a molecular level. The elemental distribution as a function of the sputtering time is obtained, and the formation of two layers is observed-one hydroxide (mainly iron-nickel based) on top and a second one deeper, mainly consisting of iron-chromium oxides.
authors.affiliation: SCK CEN Reactor Materials Research (LHMA), Boeretang 200, 2400 Mol, Belgium. igntova@cnt.fraunhofer.de
authors.forename: Velislava A
authors.initials: VA
authors.lastname: Ignatova
authors.forename: Sven
authors.initials: S
authors.lastname: Van Den Berghe
authors.forename: Steven
authors.initials: S
authors.lastname: Van Dyck
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Popok