The investigation of multiply twinned Ll0-type FePt nanoparticles by transmission electron microscopy

Thin films of FePt nanoparticles were prepared by co-deposition of Fe and Pt on to amorphous C films kept at 350 degreesC. As-prepared films were composed of disordered Fe - Pt nanoparticles with a fcc structure, where twinned and multiply twinned Fe - Pt nanoparticles could be identified by transmission electron microscopy (TEM) and electron diffraction. Atomic ordering from fcc to L1(0) structure was followed by in-situ TEM observation during heating up to 750 degreesC. Multiply twinned (fivefold) nanoparticles of the L1(0) FePt were observed for the first time by high-resolution TEM observation. In these nanoparticles the crystallographic c axes of L1(0) structure is oriented parallel to the film plane in each segment. The stability of the fivefold FePt nanoparticles is briefly discussed.