Fabrication of monodispersive FePt nanoparticle films stabilized on rigid substrates

Monodispersive FePt nanoparticle films can be stabilized firmly on rigid Si substrates using amino-functional silane, such as [3-(2-aminoethlyamino) propyl]trimethoxysilane, as a coupling layer. The Si $\mathrm{substrate}/{\mathrm{SiO}}_2/\mathrm{APTS/FePt}$ nanoparticles heterostructure was confirmed using high-resolution electron microscopy (HREM). The HREM result agreed well with the x-ray reflectivity measurement upon the individual layer thickness. The as-made superparamagnetic FePt nanoparticle film transformed from chemically disordered fcc structure to chemically ordered $\mathrm{L}{1}_0$ phase upon annealing at 800 °C for 30 min under a vacuum of ${10}^{\text{−8}}\hspace{0.17em}\mathrm{Torr}.$ Plan-view high-resolution scanning electron microscopy (HRSEM) observation indicated that under high-vacuum annealing, coalescence of the monodispersive nanoparticle film was not significant. The HRSEM result was consistent with the in-plane x-ray diffractometry measurement, in which sharpening of the diffraction peaks occurred only very slightly for the annealed films.