Microscopic Formation Process and Local Structure of Reaction Products Formed on Iron Surface by Exposure to Air

Abstract

Reaction products such as iron oxide and oxyhydroxide are formed on the surfaces of iron and steel by exposing them to air at room temperature for a long time. Microscopic formation processes and the local structure of the reaction products formed on the iron surface were investigated by using XPS, EXAFS and Mössbauer spectroscopy. Angle-resolved measurements of XPS spectra showed that an oxyhydroxide layer covers a native oxide layer formed on the iron surface. Imaging by micro XPS indicated that fine reaction products, which are oxyhydroxides, are heterogeneously formed on the iron surface by exposure to air for a long time. Experimental results by EXAFS and Mössbauer spectroscopy were also shown to discuss the local structure of the reaction products on the iron surface.