Phase formation after high fluence implantation of Fe in AlN: A Mossbauer study

To study the chemical bonds which can be formed by ion implantation of metals in a ceramic matrix, we have performed Mossbauer spectroscopy with Fe-57 in implanted and post-annealed AlN samples at Fe concentrations from 10 at% to 40 at%. Characterization of the Fe local environment led to the following results: part of Fe is surrounded by N and the rest is in the form of Fe clusters, the relative amount of Fe in each phase depending on both implanted concentration and post-annealing treatment. Formation of the observed nitride phase can be interpreted by substitution of Al atoms by Fe ions which leads to a FeN stoichiometry. These results are analyzed in relationship with the formation enthalpies of the different phases.