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Recently nanocomposites with sensoring function are becoming a new area of interest in the field of optical gas sensor. In fact, the optical transmittance of nano-particles or thin films has been reported to be changed by atmosphere gases. In particular it was found that NiO, Co 3 O 4 and Mn 3 O 4 thin films showed reversible decrease in the Vis-NIR absorption due to CO. Aim of this work is the synthesis and the characterization of SiO 2 sol-gel glass films doped with NiO nanocrystals. Films of composition (100-X)SiO 2 -XNiO with X = 10, 20, 40, were obtained by mixing a matrix solution of Si(OC 2 H 5 ) 4 (TEOS) and CH 3 Si(OC 2 H 5 ) 3 (MTES) as SiO 2 precursors, with a doping solution containing NiCl 2 as precursor for NiO particles. 3-Aminopropyltriethoxysilane (3-APTES), bearing either an ammine group capable of coordinating the Ni ions and hydrolysable siloxane groups for anchoring the metal complex moiety to the silicate matrix, was used as bifunctional ligand. Transmission electron microscopy micrographs showed a uniform distribution of round shaped nanoparticles in film heated at 500°C with a mean diameter of 2.5 nm. The film composition evaluated from Rutherford backscattering spectrometry.was in good agreement with the nominal one. As expected the density of the films heated at 1000°C is much higher than the density of the film heated at 500°C due to a residual porosity. Fourier transform infrared spectra also confirmed the presence of residual porosity in the films heated at 500°C.

The sensitization of the infrared luminescence of Er ions by Si clusters is studied in oxide films derived from tetraethoxysilane and triethoxysilane gels, doped chemically or by ion implantation with Er and/or Si. No quenching of the luminescence by impurities and structural defects is observed with respect to ion-implanted silica, and a maximum enhancement is observed in the SiO1.5 suboxide formed from triethoxysilane. The segregation of erbium silicide or oxide, depending on the synthesis procedure, deactivates the Er ions when their concentration exceeds 1 at % or the temperature of annealing is above 1050 °C.

The transformations induced by ion irradiation in films of polycarbosilane and gels derived from tetraethoxysilane, methyltriethoxysilane and triethoxysilane have been studied. Hydrogen is released selectively under the effect of electronic excitations at a rate depending on the probability of H radicals to combine for forming molecules inside the film. The radiolysis efficiency of C—H bonds is the lowest and that of Si—H bonds the highest. Beside the conversion of the polymeric structure into an amorphous ceramic, ion irradiation induces the precipitation of C or Si clusters, according to the precursor, leading to a noticeable luminescence in the visible. This precipitation has been put into evidence for the first time by energy filtered electron microscopy.

Silicon nanoclusters formed in triethoxysilane during annealing at temperatures above 900°C are used for increasing the excitation cross section of Er atoms. A stronger sensitization of the Er luminescence is observed, for a given Er concentration, when the Er3+ ions are introduced in the matrix by ion implantation than when adding a salt to the precursor solution, because of a better dispersion of the implanted atoms. The logarithmic increase of the emission yield with the Er concentration up to 1 at% which is found in the case of implanted samples is ascribed to the quenching processes by interaction between neighbour Er3+ ions.

Precipitation of silver clusters in silica is achieved by different methods: ion implantation, ion beam mixing of superimposed layers and ion irradiation of films deposited by means of co-sputtering or sol-gel technique. Main features of the nanoparticles depending on the preparation method are investigated by TEM. The optical extinction resonance of these clusters is analysed in terms of sizes and interaction between the clusters on the basis of calculations. We found that resonances in sputtered and gel films with low metal concentrations are well described by plasmon polaritons in isolated clusters and calculations based on Mie theory allow the study of their growth under irradiation. This theory is not appropriate to describe the optical response of silver clusters in silica implanted with Ag concentrations higher than 5 at.% or in ion beam mixed films, because of the interaction between clusters. Using an effective medium model, it is demonstrated that the random dispersion of clusters in implantation films causes fluctuations and, on average, an increase of the clusters polarization. On the contrary, the particular arrangement of the clusters with a bimodal size distribution in ion beam mixed films induces a screening effect between the clusters of largest size.

We present results of X-ray fluorescence measurements (carbon Kα and Si L2,3) of methylhydroxylsiloxane and phenylmethylhydroxylsiloxane films. The films are converted into amorphous ceramics by irradiation with 500 keV C and 3 MeV Au ions. Changes in the composition (O/Si ratio) of some polysiloxane films are found when treated with ion irradiation. It is shown that ion irradiation induces a segregation of carbon atoms from methyl groups into diamond-like clusters whereas carbon atoms from phenyl groups maintain their sp2 configuration.

Thin silica films embedded with Au nanoparticles (NPs) were prepared by atom beam co-sputtering and RF-magnetron sputtering. The growth kinetics of Au NPs in atom beam co-sputtered film, under 90 MeV Ni ion irradiation, was studied by in-situ X ray diffraction experiment in the materials science beam line at IUAC, New Delhi. The growth of NPs from 4 nm (for pristine) to 9 nm at a fluence of 1 × 1014 ions/cm2 was observed with rapid growth upto the size track diameter, however slowed beyond it. 120 MeV Au ion irradiation of RF magnetron sputtered films resulted in the elongation of Au NPs along ion beam direction. The aspect ratio of elongated NPs (Au nanorods) is found to be ∼3.5, which mainly depends on the electronic energy deposited within the system. Hence the present work reports that the ion irradiation is an effective tool for tailoring the size, shape and size distribution of NPs. The results are discussed in the framework of thermal spike model.

The conducting carbon nanowires embedded in fullerene matrix are synthesized by high energy heavy ion irradiation of thin fullerene film. We report the control growth of carbon nanowires, their electrical and field emission properties. The typical diameter of the conducting tracks is observed to be about 40 to 100 nm. The conductivity of the conducting zone is about seven orders of magnitude higher than that of the fullerene matrix. Conducting atomic force microscopy evidences the conducting nano wires. All the nanowires are parallel to each other and are perpendicular to the substrate. The density (spacing), growth direction and length of these carbon nanowires simply can be changed by ion fluence, angle of irradiation and the film thickness, respectively. The field emission measurements on these nanowires reveal that the threshold voltage is about ( ~13 V/mm), whereas the as deposited fullerene films shows a break down at ( ~ 51 V/mm). The present approach of making controlled conducting carbon nanowires is quite promising, as it takes few seconds of ion irradiation and no catalyst is required.

The first part of this review surveys the forms of energy exchange between incident ions and target atoms, going on to an examination of the distribution in depth of deposited energy. This analysis is then used to interpret the sputtering yield under various circumstances. The last part of the paper is devoted to a survey of different forms of radiation damage in sputtered targets, with special reference to the many factors that modify the original composition profile: such modification is related to the bombardment conditions used in analytical techniques such as AES, ESCA or SIMS which may be used,inter alia, to determine composition profiles.

Single-phased films of α-Ti1−x Nx, ∊-Ti2Nx, or δ-TiNx with a homogeneous composition on more than 400 nm were produced by ion implantation at several different energies in the TiAl6V4 alloy. Secondary ion mass spectroscopy (SIMS) profiles and ionic images recorded within the tracks after incremented cycles of friction against a 35NCD16 steel ball in air have shown that a Ti–O–C–N film is progressively formed on the surface of α solid solutions, while more concentrated nitride films resist oxidation. The friction and abrasion resistances of ∊ or δ nitride films are initially improved for a time lasting for as long as their N content increases, but they are finally self-destroying. On the contrary, the hardening effect of N in an α-Ti matrix keeps a really severe amount of abrasion from occurring during running in of the implanted surface, without suppressing the building up of a lubricant oxide hardened by N.