MÖssbauer Effect Study of Fe Grains in Nanocomposites

Abstract

The magnetic properties of Fe grains were studied by MOssbauer spectroscopy in three different nanocomposite systems: Fe-Zr-B-Cu nanocrystalline alloys prepared from melt quenched amorphous precursors, and Fe / B and Fe / Ag multilayers prepared by vacuum evaporation. It is shown that non-equilibrium alloying plays an overwhelming role in the deviation of the value of the Fe hyperfine field in small particles and in the bulk. On the other hand, a grain boundary phase with distinct magnetic properties cannot be separated. With decreasing grain size the super-paramagnetic behaviour of the Fe grains becomes more dominant and a coexistence of ferromagnetic and superparamagnetic particles can be observed. Multilayer deposition is shown to be a flexible tool for preparing magnetically heterogeneous nanocomposite structures with narrow size distributions, offering new possibilities to study the magnetic interactions between nanosize objects.