Platinum-Rich Solid Solution in Nanostructured FePt System

Features of phase formation and properties of solid solutions in the nanostructured FePt system synthesized by reducing the aqueous solutions of precursors by hydrazine hydrate are considered. It is established by means of X-ray diffraction studies and elemental analysis involving optical emission spectroscopy that limited solid solutions with the fcc type structure are formed under the conditions of the samples with the component ratio Pt/Fe >= 0.5. With iron content (C-Fe) <= 11.6 +/- 0.7 at. %, the system is monophase (an fcc-solid solution), with higher iron content it is composed of two phases (an fcc-solid solution with C-Fe = 11.6 +/- 0.7 at. % and a diffraction-invisible phase relatively enriched with iron). The size of the coherent scattering region for the solid solution varies from 7 to 9 nm. The presence of Fe3+ was revealed in all samples by means of electron paramagnetic resonance. Small amounts of iron hydroxide and oxides were detected by means of XRD in the samples with a high iron content. The temperature regions of O-2 and CO2 desorption, thermal decomposition of extrinsic FeO(OH) and crystallite agglomeration accompanied by phase transformations were determined in the studies of thermally stimulated processes.