Local structure, optical and magnetic studies of Ni nanostructures embedded in a SiO₂matrix by ion implantation

Abstract

This work reports the formation of Ni nanostructures, their growth and saturation to form oxides by using ion implantation and thermal treatment in air at 600 • C. A quartz (SiO 2 ) matrix was implanted with 100 keV Ni + ions to doses in the range 5 × 10 15 -2 × 10 17 ions cm −2 . The formation of Ni nanoclusters was observed by high resolution x-ray diffraction (HRXRD), UV-visible optical spectroscopy, dc magnetization, AFM/MFM and x-ray absorption spectroscopy (XAS). The cluster size distribution is narrow, with an average size of ∼25 ± 0.5 nm for the sample implanted at a dose of 1 × 10 16 ions cm −2 , but increases with implantation dose. Optical absorption spectra also show a clear signature of a surface plasmon resonance (SPR) peak at around 388 nm in accordance with the theoretical Mie's spectra. Temperature dependent zero-field-cooled and field-cooled magnetization measurements clearly indicate a superparamagnetic behavior, which is properly analyzed considering the size distribution of the magnetic nanostructures. The results show that the magnetic properties of the nanoparticles can be controlled by the implantation dose. A detailed investigation of the local structure using Ni K-edge NEXAFS/EXAFS suggests that the size of the Ni nanostructures is altered by implantation dose, reaching saturation in the form of oxides/silicates of Ni at a dose of 2 × 10 17 ions cm −2 .

Aurivillius phases of PbBi4Ti4O15 doped with Mn3+ synthesized by molten salt technique: Structure, dielectric, and magnetic properties

“…The higher symmetric condition in Ti(1)O 6 give an indication that the Mn ions could mainly distributed at this site. We could explain as follows: the filled or partially filled d-orbitals of transition metal ions could easily hybridize with the O 2p orbitals [28] and this hybridization could lead to high symmetrical octahedra or similar bond length between Mn ion with oxygen ions at the opposite direction. The high symmetrical of Mn octahedra then would favor in residing in the inner TiO 6 octahedra since it has lowest distortion compared to the outer octahedra.…”

Effect of 100 MeV O7+ ion beam irradiation on structural, optical and electronic properties of SnO2 thin films

“…The ion beam's effect on the material depends on the ion energy, fluence and ion species. Low-energy ions (∼100 keV/nucleon), available from ion implanters, have been used in various implantation experiments, and the growth of embedded nanostructures has been also achieved at the desired depth in polymer and insulator matrices (5,6). High-energy ions (energy >1 MeV/nucleon) with velocity equivalent to the Bohr velocity, known as swift heavy ions (SHIs), have been used for the engineering of materials with the unique feature of electronic energy deposition (3)(4)(5).…”

Ion beam synthesis of Ni nanoparticles embedded in quartz

“…The magnetic interaction among Ni particles embedded in quartz and their local structure were reported recently. 25 For device fabrication, we need to grow nanoparticles of average size of ϳ2 -3 nm. For this purpose, studies on the optimization of ion beam parameters are being done.…”