X-ray diffraction and absorption spectroscopy studies of the structure of self-assembled FePt nanoparticles during annealing

The superlattice structures and coalescence of self-assembled FePt nanoparticles were studied by X-ray diffraction and absorption spectroscopy techniques. The as-synthesized superlattice structure was found to be an FCC-like one with 21±0.5 well-packed layers. During the annealing, the iron absorption K edge was found shifted to a higher energy as the annealing temperature increase. The shift of this iron K edge might be attributed to the quantum size effect, surface effect or oxidation effect.