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Presents information on a study that examined the effects of xenon bombardment on carbonitrides produced by nitrogen implantation in a low-carbon steel via conversion electron Mössbauer spectroscopy and nuclear reaction analysis. Dissolution of the produced carbonitrides; Modification of the thermal behavior of the precipitates; Irradiation with argon ions.

Discusses a study which examined the iron-nitrogen phase transformations produced by the simultaneous use of temperature and ion bombardment. Principle behind nitrogen implantation; Description of the experimental setup; Findings.

Abstract: In this work, SiO2 layers containing Ge nanocrystals (NCs) obtained by the hot implantation approach were submitted to an ion irradiation process with different 2MeV Si+ ion fluences. We have investigated the photoluminescence (PL) behavior and structural properties of the irradiated samples as well as the features of the PL and structural recovery after an additional thermal treatment. We have shown that even with the highest ion bombardment fluence employed (2×1015 Si/cm2) there is a residual PL emission (12% from the original) and survival of some Ge NCs is still observed by transmission electron microscopy analysis. Even though the final PL and mean diameter of the nanoparticles under ion irradiation are independent of the implantation temperature or annealing time, the PL and structural recovery of the ion-bombarded samples have a memory effect. We have also observed that the lower the ion bombardment fluence, the less efficient is the PL recovery. We have explained such behavior based on current literature data. [Copyright &y& Elsevier]

We report the results of an experimental-theoretical study on the stopping power of ZrO2 films for swift H and He ion beams. The experiments, using the Rutherford Backscattering technique, were done for protons with incident energies in the range 200–1500 keV and for α-particle beams with energies in the range 160–3000 keV. The theoretical calculations were done in the framework of the dielectric formalism using the MELF-GOS model to account for the ZrO2 target electronic response. It is shown that for both ion beams, the agreement between theory and experiment is quite remarkable. [ABSTRACT FROM AUTHOR]

We report an experimental-theoretical study of the energy-loss straggling of protons and alpha particles in HfO2 films. In the case of H ions the experiments were performed in the energy range 40–1750 keV. For the lower energy interval (40–250 keV) we have used the medium energy ion scattering (MEIS) technique with a resolution of ΔE/E∼ 4×10-3, while for the higher energies the Rutherford backscattering technique (RBS) was employed with an overall resolution of 7 keV. Concerning the He ions the straggling study has covered an energy range between 250 and 3000 keV by using RBS measurements, which in this case had a resolution better than 10 keV. The theoretical calculations were done in the framework of the dielectric formalism using the MELF-GOS model to obtain a proper description of the energy loss function (ELF) of the HfO2 target. It is shown that for both projectiles the experimental data and the theoretical predictions for the energy-loss straggling display a very good agreement. [ABSTRACT FROM AUTHOR]

The diffusion of 15N in α-Ti was studied in the 673–1023 K temperature range by using the ion implantation and nuclear resonance techniques. The measurements show that the diffusion coefficients follow an Arrhenius behavior D(T)=D0 -Q/RT, where D0=(1.1±0.8)×10-7 m2 s-1 and Q=(183±2) kJ/mol. A comparison with previous results is also given. [ABSTRACT FROM AUTHOR]

Phosphorus depth profiles in Si obtained by 140 keV implantation in the [001] axial channel direction and in a direction 7° off axis are investigated at two different doses (5 × 10[SUP13] and 5 × 10[SUP15]cm[SUP-2]) for implantation temperatures of 350 °C and room temperature (RT). At low dose and at channeling incidence, the penetration depth of implanted ions is higher at RT than at 350 °C. This behavior is caused by the dechanneling of lattice vibrations. At high dose, the temperature dependence of the shape of the implantation profile is opposite that at low dose, due to enhanced dechanneling by defect accumulation at RT. On the other hand, damage buildup does not occur at elevated temperature. The temperature dependence of the profiles obtained by tilted implantation is much less than for the channeled implants. The P profiles measured can be reproduced very well by atomistic simulations which take into account both lattice vibrations and defect accumulation during ion bombardment. [ABSTRACT FROM AUTHOR]

Examines the ion-beam-induced epitaxial crystallization of amorphous silicon implanted with iron. Detection of layered structure in ion-irradiated specimen; Relationship of the phase distribution with iron concentration profile; Formation of alpha-iron silicon[sub 2] around the peak of iron profile.

Examines the ion beam synthesis of iron disilicide. Occurrence of cubic precipitates as shown in high resolution electron microscopy; Avoidance of channeled implantation; Superimposition of weak spot regular arrays on silicon spots.

Abstract: In the present work we have studied the photoluminescence (PL) behavior from Si nanocrystals (NCs) as a function of the excitation power density and annealing time. The NCs were produced in a SiO2 matrix by Si implantations from room temperature (RT) up to 700°C, followed by post-annealing in N2 atmosphere at high temperature. With this aim we have changed the excitation power density (from 2×10−3 W/cm2 up to 15W/cm2) and the annealing time (from 10min up to 15h). The strong PL signal, which at 15W/cm2 is composed by a single-peak structure (650–1000nm) centered at around 780nm, expands up to 1200nm showing a two-peak structure when measured at 20×10−3 W/cm2. The peak structure located at the short wavelength side is kept at ∼780nm, while the second peak, starting at around 900nm, redshifts and increases its intensity with the implantation temperature and annealing time. The effect of the annealing time on the PL spectra behavior measured at low excitation power agrees by the first time with the Si NC growth according to quantum confinement effects. [Copyright &y& Elsevier]

Abstract: In this work we present a photoluminescence (PL) study on Si nanocrystals produced by ion implantation on SiO2 targets at temperatures ranging between 25 and 800°C and subsequently annealed in N2 atmosphere. The PL measurements were performed at low excitation power (20mW/cm2) in order to avoid nonlinear effects. Broad PL spectra were obtained (from 650 up to 1050nm), presenting a line shape structure that can be reproduced by two superimposed peaks at around 780 and 950nm. We have observed that both PL intensity and line shape change by varying the annealing as well as the implantation temperatures. Implantations performed at 400°C or higher produce a remarkable effect in the PL line shape, evidenced by a strong redshift, and a striking intensity increase of the peak located at the long wavelength side of the PL spectrum. [Copyright &y& Elsevier]

Abstract: The present work describes a new method to produce membranes of poly(Acrylic-acid-Xmonomer) using the grafting procedure. PVDF foils irradiated with Ar+ beam with energies between 30 and 150keV were employed as substratum. Different combinations of monomers in water solutions were used: acrylic acid (AAc); acrylic acid–glycidyl methacrylate (AAc–GMA); acrylic acid–styrene (AAc–S), acrylic acid-N-isopropyl acrylamide (AAc–NIPAAm) and acrylic acid-N-isopropyl acrylamide–glycidyl methacrylate (AAc-NIPAAm–GMA). A large percentage of grafting results for specific values of: ion fluence and energy, AAc and sulfuric acid concentration, and different substrata PVDF polymorphous (alpha or beta). At a particular time of the grafting process, the poly(AAc-Xmonomer) membranes detach from the substratum and continue their grafting in the solution. This method is useful to produce increased replicated membranes of the irradiated original surface. [Copyright &y& Elsevier]

Abstract: A study of ion beam analysis techniques of plasma enhanced chemical vapor deposited (PECVD) silicon oxide thin films (1μm thick) obtained from silane (SiH4) and nitrous oxide (N2O) is reported. The film, elemental composition and surface morphology were determined as function of the reactant gas flow ratio, R =[N2O]/[SiH4] in the 22–110 range using the Rutherford backscattering spectrometry, nuclear reaction analysis and atomic force microscopy techniques. The density of the films was determined by combining the RBS and thickness measurements. All the experiments were done at a deposition temperature of 300°C. In all the cases almost stoichiometric oxides were obtained being the impurity content function of R. It was also observed that physical properties such as density, surface roughness and shape factor increase with R in the studied interval. [Copyright &y& Elsevier]

Abstract: As part of the studies of new materials to be used as electrodes for plasma torches, polycrystalline copper thin film substrates, obtained by depositing copper on silicon wafer using the Electron Beam technique, were implanted with low energy (20–50 keV) alkali ions. The samples, before and after implantation process, were analysed in terms of surface composition and work function changes. Although the implantation doses were low (3×1015 ions/cm2), relatively high concentrations of alkali metals were detected on the surface, which yielded a work function decrease of 3–9% in relation to the copper value. [Copyright &y& Elsevier]

Abstract: Ion irradiation of polymers offers a number of interesting possibilities for applications. In the case of latent tracks, radiochemical changes, phase transitions, alterations of the intrinsic free volume, or radiation induced defects can be exploited – the latter ones to trap mobile impurities. These approaches are useful to form, e.g. new types of sensors. Apart from this, etched tracks in polymers offer a vast range of possibilities. Practically any material – including colloides and nanocrystals – can be inserted into these pores to form nanowires or nanotubules. Sequential deposition can be made as well in radial as axial direction to form complex nanostructures. Combination with lithography enables one to form different types of novel transistors, microcapacitors, -magnets, -transformers and -sensors. Also sterilizing foils for medicine and packing industry have been made in this way. A number of new ideas are presented how to proceed further in this field. [Copyright &y& Elsevier]

In the present work we report on significant modifications of the surface structure of Au thin films deposited over polymers induced by heavy ion beam irradiation. Under 2 MeV Au+ ion beam irradiation, performed with the target at 200 °C, the combination of RBS and AFM analysis demonstrates the formation of gold clusters with nanometric dimensions of about 115 nm size and 40 nm high. These clusters have irregular shapes and are randomly distributed over a heavy damaged polymer layer, with first neighboring distance of about 150 nm. Annealed material, at the same temperature and time, do not show the formation of these clusters. This fact gives support that an ion beam radiation process takes place. [Copyright &y& Elsevier]

The treatment of stainless steel by pulsed energetic nitrogen ion irradiation in the millisecond regime may cause phase transformations close to the surface. The characterization of the phases was done by measurements of Mo¨ßbauer and grazing incidence X-ray diffraction. The results indicate transformations of the austenitic phase into Cr2N, Fe2N and the γN-phase (paramagnetic and magnetic) in dependence on the bombardment conditions and the nitrogen depth profiles measured by nuclear reaction analysis. Some samples were studied by depth selective conversion electron Mo¨ßbauer spectroscopy. One of these samples contained three new phases: Fe2N, γN2-phase (paramagnetic) and γN1-phase (magnetic). The magnetic phase is found predominantly in the surface region, whereas the Fe2N and the γN2-phase (paramagnetic) reach their maximum concentration at a depth of approximately 100 nm. The other sample contained four new phases: the three phases mentioned above and additionally α-(Fe,Ni)—martensite, indicating the formation of Cr2N. This phase reaches its maximum concentration at a depth of approximately 40 nm. Thus, by interaction of different mechanisms, i.e. segregation of Cr and formation of Fe–Ni rich clusters by radiation enhanced diffusion, the α-(Fe,Ni)-phase is formed on the expense of the other phases. Hardness was measured as Vickers hardness and current-density/potential-curves in a 5 N H2SO4-solution were performed as corrosion tests. The influence of the different surface phases on mechanical and chemical properties are discussed. [Copyright &y& Elsevier]