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Ion Fluence (ion + fluence)
Selected AbstractsPhysically and chemically modified polycarbonate by metal ion implantationADVANCES IN POLYMER TECHNOLOGY, Issue 3 2008Rashi Nathawat Abstract Changes in physical and chemical properties have been studied for polycarbonate (PC) implanted by 100 keV Ni+ with various fluences from 1 × 1014 to 1 × 1016 ions/cm2. Changes in the surface morphology and composition have been observed with atomic force microscopy and X-ray diffraction (XRD). Ni particles as precipitates in PC were observed by cross-section transmission electron microscopy at the 100-nm depth. Ion implantation induces changes in the topography of PC as indicated by a dramatic increase in surface roughness with ion fluence. Implanted metal ions show direct evidence of compound formation on the surface. Chemical changes in the surface region have been observed by Raman spectroscopy and UV,vis spectroscopy. UV,vis absorption analysis indicates a drastic decline in optical band gap from 5.46 to 1.76 eV at an implanted dose of 1 × 1016 ions/cm2. It is shown that partial destruction of the original chemical bonding under ion implantation leads to the creation of new amorphous and graphite-like structures, which are confirmed by Raman spectroscopy. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:143,151, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20130 [source] Impact of H+ ion beam irradiation on Matrimid®.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Abstract Ion beam irradiation is an easily controlled method to modify the chemical structure and microstructure of polymers including the fractional free volume, free volume distribution and chain mobility, thus altering the gas transport properties of the irradiated polymers. The previous paper focused on the impact of H+ ion beam irradiation on chemical structural evolution of the polyimide Matrimid®. This paper focuses on the impact of H+ ion beam irradiation on microstructure and gas permeation properties of Matrimid®. Irradiation at low ion fluence resulted in slight decreases in permeabilities for five gases (i.e., He, CO2, O2, N2, and CH4) with increases in permselectivities for some gas pairs (e.g., He/CH4 and He/N2). In contrast, irradiation at relatively high ion fluences resulted in simultaneous increases in permeabilities and permselectivities for most gas pairs (e.g., He/CH4, He/N2, O2/N2, and CO2/CH4). While Matrimid® has bulk gas permeation properties that are below the range of commercially interesting polymers, samples irradiated at high ion fluences exhibited significant improvement in gas separation performances. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1670,1680, 2007 [source] Silver nanocluster containing diamond like carbonPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2008F. Schwarz Abstract Applying Diamond Like Carbon (DLC) as medical coating has become well established since large scale plasma processes like Plasma Immersion Ion Implantation and Deposition (PIII&D) are available. Now the focus of research lies on systematic modification of certain biological relevant properties and the most recent field of interest turned to generating antimicrobial behaviour. This is desirable for medical tools as well as for different types of medical implants. Since silver and copper are known to provide a bactericidal effect, one tries to introduce clusters of these noble metals into the carbon matrix. The basic principle of the method presented is to convert a metal containing polymer film into DLC by ion bombardment. In this paper the hydrogenated DLC matrix is characterized and the evolution of the metal particles is studied. By means of film composition (RBS/ERD), bonding structure (Raman spectroscopy) and hardness (nanoindentation), the dependency of these material properties on ion species, energy and fluence is investigated. TEM imaging is used to visualize the film structure. Upon ion irradiation of the polymer films, increased density and considerable loss of hydrogen can be observed, which both are controlled by ion fluence and mass. The crosslinking of the carbon network, caused by hydrogen drive out as well as atomic displacements in collision cascades, results in the formation of a-C:H. The silver particles in the film some ion induced growth, but still remain as nanoclusters in the a-C:H matrix. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Variation of electrical resistance in metallic glasses subjected to 130 MeV 28Si ion irradiationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2004H. Narayan Abstract The change in the electrical resistivity of 2605SC (Fe81B13.5Si3.5C2) and 2705M (Co69B12Si12Fe4Mo2Ni1) metallic glasses (MGs) resulting from 130 MeV 28Si ion irradiation has been investigated. Resistivity as a function of temperature has been measured off-line and in situ before and after irradiation, and on-line as a function of ion fluence. The results show that for the 2605SC MG electrical resistivity increases by 5.2% (fluence = 3.7 × 1014 ions/cm2) and 4.5% (fluence = 1.6 × 1014 ions/cm2). This has been explained on the basis of the ,two-hit model'. For the 2705M MG, however, an unexpected decrease of electrical resistivity of about ,9.6% (fluence = 1.1 × 1016 ions/cm2) and ,8.7% (1.3 × 1014 ions/cm2) is observed, which has been attributed to irradiation-induced structural modification. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Role of structural modification on the electrical properties of poly(ethylene terephthalate) irradiated with 90-MeV carbon ion beamPOLYMER ENGINEERING & SCIENCE, Issue 6 2008A. Srivastava Thin films of poly(ethylene terephthalate) (PET) having a thickness of 100 ,m were exposed to different ion fluence of swift heavy ions of carbon in the range of 5 × 1011 , 5 × 1013 ions/cm2. The effect of ion beam on structural and electrical modification has been studied by UV/vis, FTIR, X-ray diffraction (XRD), Differential Scanning Calorimetery (DSC), and AC electrical measurement techniques. On irradiation, a shift in absorption wavelength toward the red end of spectrum with increase of ion fluence was observed. The intensity of crystalline IR bands and main diffraction peak in XRD pattern were found to decrease with increase in ion fluence. It indicates the loss of crystallinity induced by ion-beam irradiation. The crystallite size was found to increase on irradiation. The melting temperature (Tm) of PET films increased at a low ion dose (5.0 × 1012 ions/cm2), while it decreased at higher ion fluence (50.0 × 1012 ions/cm2). The dielectric constant (,,) of PET films was increased with increase of ion fluence. The modifications brought about in the dielectric constant are correlated with chemical and molecular structural changes occurring on irradiation. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. [source] Strain-profile determination in ion-implanted single crystals using generalized simulated annealingJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5-1 2010Alexandre Boulle A novel least-squares fitting procedure is presented that allows the retrieval of strain profiles in ion-implanted single crystals using high-resolution X-ray diffraction. The model is based on the dynamical theory of diffraction, including a B-spline-based description of the lattice strain. The fitting procedure relies on the generalized simulated annealing algorithm which, contrarily to most common least-squares fitting-based methods, allows the global minimum of the error function (the difference between the experimental and the calculated curves) to be found extremely quickly. It is shown that convergence can be achieved in a few hundred Monte Carlo steps, i.e. a few seconds. The method is model-independent and allows determination of the strain profile even without any `guess' regarding its shape. This procedure is applied to the determination of strain profiles in Cs-implanted yttria-stabilized zirconia (YSZ). The strain and damage profiles of YSZ single crystals implanted at different ion fluences are analyzed and discussed. [source] Impact of H+ ion beam irradiation on Matrimid®.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Abstract Ion beam irradiation is an easily controlled method to modify the chemical structure and microstructure of polymers including the fractional free volume, free volume distribution and chain mobility, thus altering the gas transport properties of the irradiated polymers. The previous paper focused on the impact of H+ ion beam irradiation on chemical structural evolution of the polyimide Matrimid®. This paper focuses on the impact of H+ ion beam irradiation on microstructure and gas permeation properties of Matrimid®. Irradiation at low ion fluence resulted in slight decreases in permeabilities for five gases (i.e., He, CO2, O2, N2, and CH4) with increases in permselectivities for some gas pairs (e.g., He/CH4 and He/N2). In contrast, irradiation at relatively high ion fluences resulted in simultaneous increases in permeabilities and permselectivities for most gas pairs (e.g., He/CH4, He/N2, O2/N2, and CO2/CH4). While Matrimid® has bulk gas permeation properties that are below the range of commercially interesting polymers, samples irradiated at high ion fluences exhibited significant improvement in gas separation performances. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1670,1680, 2007 [source] | |||||||||||||