title: Structural stability of icosahedral FePt nanoparticles.
abstract: The structural stability of FePt nanoparticles of about 5-6 nm diameter was investigated by dynamic high resolution transmission electron microscopy. The FePt icosahedra were very stable under an electron beam flux of approximately 20 A/cm(2) at 300 kV. Surface sputtering was suppressed due to the large sputtering threshold energy of a Pt-rich shell. Under a flux of approximately 50 A/cm(2), the trapping potential well of the FePt particle on the supporting carbon film was lowered by the magnetic interaction between the electron beam and the particle, which leads to rotational and translational motions of the particle. A large dose of electrons (approximately 200 A/cm(2)) initiated melting and recrystallization of the FePt particle. The structure of the FePt nanoparticle, a Pt enriched shell around an Fe/Pt magnetic core, is believed to be responsible for its dynamic behaviour under different beam conditions.
authors.affiliation: Key Laboratory of Micro-nano Measurement, Manipulation and Physics, Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing, 100191, PR China. rmwang@buaa.edu.cn
authors.forename: Rongming
authors.initials: R
authors.lastname: Wang
authors.forename: Hongzhou
authors.initials: H
authors.lastname: Zhang
authors.forename: Michael
authors.initials: M
authors.lastname: Farle
authors.forename: Christian
authors.initials: C
authors.lastname: Kisielowski