title: Ion beam-induced shaping of Ni nanoparticles embedded in a silica matrix: from spherical to prolate shape.
abstract: Present work reports the elongation of spherical Ni nanoparticles (NPs) parallel to each other, due to bombardment with 120 MeV Au+9 ions at a fluence of 5 × 1013 ions/cm2. The Ni NPs embedded in silica matrix have been prepared by atom beam sputtering technique and subsequent annealing. The elongation of Ni NPs due to interaction with Au+9 ions as investigated by cross-sectional transmission electron microscopy (TEM) shows a strong dependence on initial Ni particle size and is explained on the basis of thermal spike model. Irradiation induces a change from single crystalline nature of spherical particles to polycrystalline nature of elongated particles. Magnetization measurements indicate that changes in coercivity (Hc) and remanence ratio (Mr/Ms) are stronger in the ion beam direction due to the preferential easy axis of elongated particles in the beam direction.
authors.affiliation: Nanostech Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India. hsehgal_007@yahoo.com.
authors.forename: Hardeep
authors.initials: H
authors.lastname: Kumar
authors.forename: Santanu
authors.initials: S
authors.lastname: Ghosh
authors.forename: Devesh Kumar
authors.initials: DK
authors.lastname: Avasthi
authors.forename: Debdulal
authors.initials: D
authors.lastname: Kabiraj
authors.forename: Arndt
authors.initials: A
authors.lastname: Mücklich
authors.forename: Shengqiang
authors.initials: S
authors.lastname: Zhou
authors.forename: Heidemarie
authors.initials: H
authors.lastname: Schmidt
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Stoquert