Impurity-vacancy complexes in ion-implanted iron

Abstract

The formation and annealing of impurity-defect complexes in ion-implanted iron has been studied by 119Sn Mössbauer spectroscopy. Radioactive 119In ions, decaying to the 24 keV Mössbauer state of 119Sn, have been implanted with an energy of 60 keV at temperatures around stage III (100–500 K). Large fractions of the implanted impurities are located on substitutional lattice sites. In-defect complexes are formed both athermally in the radiation-damage cascades (below 180 K) and by trapping of mobile defects (∼ 200K) at the impurities. For two different complexes, one of which anneals around 300 K, the magnetic field at the Sn nucleus is found to be larger by 10 and 20%, respectively, compared to the field of substitutional Sn. A third complex with a field lower by about a factor of three is formed in the whole temperature range up to 500 K. From the measured Mössbauer parameters the impurity-defect structures are proposed to be of the impurity-vacancy type.