CEMS analysis of Ar+ irradiated Fe/SiO2 system

A 26 nm iron film enriched to 95% in 57Fe, was deposited on a SiO2 substrate and then implanted with 100 KeV Ar+ ions. Ion-beam induced mixing at the metal/insulator interface was then investigated by conversion electron Moessbauer spectroscopy. The iron phases recognized at the interface were: a) small clusters of metallic iron dispersed in the substrate: b) an oxide phase corresponding to defect-associated Fe2+ and c) a silicate phase with Fe2+ in two octahedral sites. An explanation of the formation of the oxygen co-ordinated phases is given by inferring that the ratio of oxygen to silicon atoms displaced per incident ion in the substrate is greater than the stoichiometric ratio 2:1. (U.K.)