Evolution of texture and atomic order in annealed sinter-free FePt nanoparticles

Monodisperse FePt nanoparticles have been synthesized chemically. The spherically shaped as-made nanoparticles were 6.0 nm in size and they were single crystals. The average composition of these particles is determined as Fe(50)Pt(50). The nanoparticles did not show any sign of sintering after annealing at 800 °C for up to 120 min. The texture and order parameters of as-made and annealed FePt nanoparticles were determined from azimuthally integrated selected area electron diffraction patterns. The close to perfect [Formula: see text] axial texture in as-made particles degraded with increasing annealing time, in contrast to the order parameter, which showed a monotonic dependence on annealing time. With 60 min annealing, a 0.8 degree of chemical ordering has been achieved and the particles were sinter-free as observed from bright field images.