Ion beam-induced shaping of Ni nanoparticles embedded in a silica matrix: from spherical to prolate shape
1 Nanostech Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
2 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
3 Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
4 Institut d'Electronique du Solide et des Systèmes, 23 rue du Loess, BP 20 CR, 67037 Strasbourg Cedex 2, France
Nanoscale Research Letters 2011, 6:155 doi:10.1186/1556-276X-6-155Published: 18 February 2011
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.