Ion beam induced destabilization of icosahedral structures in gas phase prepared FePt nanoparticles -: art. no. 10N112

Multiply twinned FePt nanoparticles with icosahedral structures were prepared by dc magnetron sputtering in argon. The icosahedral structure of these particles is known to be very stable against structural transformations into both the face-centered cubic phase (fee, Al) and the chemically ordered tetragonal L1(0) phase upon in-flight or post-deposition thermal annealing. Irradiation of these multiply twinned FePt particles with 5 keV He ions, however, resulted in a transformation into predominantly single crystalline fee particles at high ion fluences of f > 10(17) ions /cm(2). Adjacent particles were observed to coalesce under the effect of He irradiation, and the size of individual particles was found to be slightly reduced, which indicates a high atomic mobility owing to temporarily enhanced defect concentrations caused by the ion bombardment. Strikingly, there was no indication for the occurrence of L1(0) ordered FePt nanoparticles upon ion irradiation in these samples. (c) 2005 American Institute of Physics.