Probing iron redox state in multicomponent glasses by XPS

Knowing the redox state of polyvalent elements in glass is important for understanding and controlling the glass properties. In this work we demonstrate the applicability of X-ray photoelectron spectroscopy (XPS) in the determination of the iron redox state in a multicomponent glass having a basalt-like composition. The XPS measurements reveal an entropy-driven reduction of ferric iron to ferrous iron upon increasing melt temperature. Furthermore, the local ferric iron enriched domains, i.e., a kind of inhomogeneity in the glass, is identified by means of XPS. It is proved that XPS is a useful and reliable tool for probing both the average redox state and inhomogeneities in glassy materials.