PREPARATION OF A NANOSTRUCTURED N-POOR IRON NITRIDE PHASE

Work package:
Nanostructured iron nitride phases are a family of low coast and sustainable nanomaterials of interest in many technological applications, from catalysis (e.g. ε-Fe2N1 and γ’-Fe4N2) to biology (ε-Fe3N3 and γ’-Fe4N4), microwave absorption (γ’-Fe4N5) and permanent magnets developments (α”-Fe16N26). The main route to these phases starts from the synthesis of iron oxide nanoparticles which are then reduced at high temperature and nitridated by exposure to ammonia.7 To avoid the first step, which is very energy consuming, our teams have jointly developed a process based on the direct nitridation of zerovalent iron nanoparticles by NH3.8 By this method, the Fe2N phase has been obtained (Fig. 1) and fully characterized. Preliminary experiments also lead to mixed materials consisting in bcc-Fe and Fe16N2 phases, or ε-Fe3N and γ’-Fe4N phases.9 The objective of this internship is to optimize the synthesis conditions to obtain a pure nitrogen-poor phase, γ’-Fe4N, which is of interest for the development of microwave absorbers, or for biomedical applications. It will therefore consist of three parts: -study of the reactivity of Fe nanoparticles with ammonia to control the rate of nitrogen incorporation -characterization of the nanomaterials obtained by the adapted analysis techniques such as: electronic microscopy, ICP analysis, DRX, magnetic measurements -evaluation in view of the application During this internship the student will learn the basics of air-sensitive material handling, how to prepare samples for the required analysis and interpretation of the results thereof, and work in an international context.