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.

Micro-structural origin of elongation in swift heavy ion irradiated Ni nanoparticles: A combined EXAFS and DFT study

“…Further details can be found in Refs. [7,11,27]. The films were subsequently annealed in Ar-H 2 gas environment at 750 C for 1 h. The annealed films (hereafter labeled as unirradiated) were subjected to 100 MeV Au þ7 SHI irradiation (with fluences 5.0 Â 10 13 ions/cm 2 , 7.5 Â 10 13 ions/cm 2 and 1.0 Â 10 14 ions/ cm 2 ) perpendicular to film-surface (to be referred as 5e13, 7.5e13 and 1e14 respectively from now on).…”

“…Experimental evidences of spherical to rod like shape transformation in Au [12], Ni [11], Co [9], Sn [10], Pt [13], FeCo [14,8] NPs are reported in literature. The changes in macro and micro structural parameters in these electronically excited metal-insulator nano-composites are studied widely in recent past using different state-of-the-art experimental approaches viz.…”

“…The formation of equally separated large arrays of nano-crystals inside a matrix [3], change in crystallographic phases [4], alterations in easy axis of magnetization [5], tuning plasmonic properties [6], enhanced field emission [7,8] are a few to be named amongst many such applications. When exposed to swift heavy ion (SHI) irradiation [9,10], the shape of embedded Ni nanoparticles (NPs) inside SiO 2 matrix gets significantly modified [11]. This leads to the possibility of tilting the easy axis of magnetization from in-plane to out-of-plane direction, giving rise to several interesting micro and macroscopic properties with possible future applications in perpendicular magnetic recording (PMR) [5].…”

Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties

“…[13][14][15] The prominent behaviors observed in nanomaterials due to irradiation effects are the change in structural and magnetic properties. Numerous investigations in the past have exposed the extrinsic impacts of ion-irradiation in nanomaterials, including thin films, 16,17 nanoparticles, 18,19 nanoparticle embedded matrices, 20,21 nanotubes, 22 nanowires, 23 and nanoparticlegranular films, where the irradiation either enhances or degrades the structural and magnetic properties.…”

Si Nanocrystal Arrays Created in SiO2 Matrix by High-Energy Ion Bombardment

“…Integrally, these effects result in general ordering of nanocrystals along ion tracks. The same processes proceed in the case of metal inclusions embedded in an insulator matrix and, as it was shown recently (Mishra et al, 2007;Giulian et al, 2010;Dawi et al, 2011;Kumar et al, 2011), irradiation with sufficiently high ion fluences and energies provides a means for forming long wire-shaped nanoparticles in ion tracks. Table 3.…”