Conversion electron Mössbauer study of LiF implanted with 57Fe ions

• DOI: 10.1016/0167-5087(83)90932-8
• Publication Date: 2002-11-11T23:43:39Z
• Authors: J. Kowalski; G. Marest; A. Perez; B.D. Sawicka; J.A. Sawicki; J. Stanek; T. Tyliszczak
• Keywords: Lithium fluoride; Quadrupole splitting; Superparamagnetism

Abstract Lithium fluoride crystals implanted with 57Fe ions at doses from 5×1015 at/cm2 to 6×1016 at/cm2 have been studied with conversion electron Mossbauer spectroscopy. It was found that iron enters the implanted zone in three well defined charge states: Fe3+, Fe2+ and Fe0 (metal). At low doses the relative fractions of Fe3+ and Fe2+ are close to 80% and 20%, which corresponds to the respective ionic fractions in an iron doped LiF sample obtained by vacuum co-deposition. With the increase in the implantation dose the Fe2+ and Fe0 fractions increase to about 40% and 30%, respectively. Annealing in vacuum results in a growth of metallic iron precipitates, whereas annealing in the presence of oxygen leads to precipitation of superparamagnetic particles of some, still unidentified, ferric compound. The Mossbauer data were related to the role of F- and F2-centres observed by optical absorption measurements. Good agreement has been achieved between the quadrupole splitting data for Fe3+ in fluorides LiF, NaF and KF and the calculated values in frames of the model of V−-Fe3+-V− defect clusters presented in our earlier work.