Ferromagnetism in Ni doped ZnS thin films: Effects of Ni concentration and swift heavy ion irradiation

International audienceThe magnetic properties of Ni doped ZnS thin films fabricated at substrate temperature of 400 degrees C by means of pulsed laser deposition are presented. The films show crystalline wurtzite structure. Optical absorption and transmission electron microscopic studies indicate that Ni has been appropriately substituted on Zn tetrahedral site. The films show ferromagnetism up to room temperature. The magnetization in the films decreases with increase of Ni concentration. Swift heavy ion (SHI) irradiations have been carried out using 120 MeV Ag ions for the modification of structural and magnetic properties of the films. SHI irradiation suggests the formation columnar ion track inside the films causing decrease in magnetization. (C) 2014 Elsevier Ltd. All rights reserved

Optical extinction resonance of Au and Ag clusters formed by ion irradiation in SiO2 and Al2O3

Three methods based on ion-beam irradiation were used to fabricate Ag and Au colloids in silica and alumina. Their surface-plasmon resonance in the visible was characterised by transmittance measurements and interpreted on the basis of transmission electron microscope observations. Despite their bimodal size distribution, particles formed by ion-beam mixing of sandwich layers exhibit much narrower resonances than those obtained by ion implantation. This unusual effect of an inhomogeneity in cluster size is ascribed to the spatial organisation of these clusters. Irradiation of supersaturated solid solutions at much lower ion fluences produces colloids with more uniform size and spatial distributions, and equally strong resonances

Formation and characterization of carbon nanowires

This article reports on the formation and electronic characteristics of conducting carbon nanowires produced by swift heavy ion irradiation of a fullerene thin film. This study shows that it is possible to create arrays of carbon nanowires, which are perfectly parallel to each other and perpendicular to the substrate. As-deposited fullerene films exhibit poor field emission characteristics with breakdown fields as high as 51 V/mu m, whereas low dose ion irradiated fullerene film produces a threshold field as low as 9 V/mu m. The present approach of making conducting carbon nanowires by ion irradiation for potential field emitters and large area applications is also discussed.</p

Synthesis, characterizations, and thermal induced structural transformation of silver-fullerene C-60 nanocomposite thin films for applications in optical devices

Nanocomposite thin films of fullerene C(60) containing Ag nanoparticles (NPs) were synthesized by thermal codeposition. The surface plasmon resonance (SPR) band of the nanocomposite film was observed in the region 450-550 nm, showing a large redshift with increasing metal concentration. This is explained by the Maxwell-Garnett effective medium theory considering the absorbing nature of fullerene C(60). The C(60)-Ag nanocomposite thin film with lowest Ag concentration was annealed at increasing temperatures in neutral atmosphere. The SPR band showed first a small redshift after annealing at small temperature then progressive blueshift at higher temperature. This behavior of SPR is explained by the increased particle-particle interaction due to the compaction of the fullerene C(60) film upon annealing at low temperature and the transformation of fullerene C(60) matrix into amorphous carbon at higher temperature. Rutherford backscattering spectrometry and transmission electron microscopy were used to quantify Ag metal content and the microstructural evolution of Ag NPs in the nanocomposite films, respectively. Thermal induced structural transformations of fullerene C(60) molecules of host matrix were investigated by Raman spectroscopy

Synthesis and characterizations of silver-fullerene C-70 nanocomposite

Films of C(70) fullerene containing silver nanoparticles were synthesized by thermal codeposition. Optical absorption studies revealed that surface plasmon resonance of Ag nanoparticles occurs at unusually large wavelength, which showed a regular redshift from 521 to 581 nm with increase in metal content from 4.5% to 28%. It is explained by the Maxwell-Garnett theory considering the absorbing nature of fullerene matrix. Rutherford backscattering and transmission electron microscopy were performed to quantify metal content and the particle size, respectively. A better detection of low intensity vibrational modes of C(70) in Raman scattering is observed due to surface enhanced Raman scattering