CEMS and TEM investigations of iron implanted with nitrogen

Abstract

It is well known that the depth distribution of nitrogen implanted into iron depends strongly on the implantation conditions. Parameters such as implanted dose or the temperature of the sample during implantation play an important role. At room temperature and low dose of implantation, the depth distribution of nitrogen is almost Gaussian and well predicted by the binary encounter theory. When the temperature during implantation is increasing (above 80°C) diffusion process takes place and the depth profile of nitrogen is split into two components: a bulk component which corresponds to nitrogen trapped in interstitial sites of the host crystal and a surface peak due to diffusion mechanism during the implantation. Resonant Nuclear Reaction Analysis (RNRA) has been used to depth profile nitrogen and Conversion Electron Mössbauer Spectroscopy (CEMS) as well as Transmission Electron Microscopy (TEM) have been used to characterize this surface component. Both techniques reveals the nature of the precipitation sites where nitrogen is trapped during diffusion process.