Ion-beam formation and track modification of InAs nanoclusters in silicon and silica

The implantation formation of InAs nanoclusters in silicon and silica and their modification via irradiation with Xe ions with an energy of 167 MeV and a fluence of 3 × 10¹⁴ cm^–2 are studied. It is found that post-implantation annealing and irradiation with high-energy ions alter the size and shape of nanoclusters and cause structural transformations within them. The ordering of nanoclusters and their elongation along the trajectory of Xe ions in a SiO₂ matrix is observed.     

Ion-beam reduction of the surface of higher niobium oxide

X-ray photoelectron spectroscopy is used to study the process of reduction of the surface of the higher oxide Nb₂O₅ upon bombardment with inert gas ions (Ar⁺) and reactive gas ions (O₂⁺) with an energy of 1 and 3 keV in high vacuum at room temperature. It is found that, upon bombardment with Ar⁺ ions, the lower oxide NbO and the intermediate oxide NbO₂ are formed in the surface layers of the oxide Nb₂O₅. Bombardment with O₂⁺ ions leads to the formation of an extremely insignificant amount of the intermediate oxide NbO₂ in the surface layers of the oxide Nb₂O₅. It is revealed that the process of ion-beam reduction of the surface of the oxide Nb₂O₅ depends on the ion type, dose, and energy of exposure.     

Ion-beam reduction of the surface of tantalum higher oxide

The process of reduction of the surface of higher oxide Ta₂O₅ under irradiation by inert gas (Ar⁺) and chemically active gas (O₂⁺) ions with an energy of 3 keV in high vacuum is investigated by X-ray photoelectron spectroscopy at room temperature. It is found that intermediate oxide TaO₂, lower oxide TaO, and metallic Ta form in the surface layers of Ta₂O₅ under Ar⁺ ion bombardment. An insignificant amount of intermediate oxide TaO₂ forms in the surface layers of Ta₂O₅ under O₂⁺ ion bombardment. Ion-beam-induced reduction of the Ta₂O₅ surface is shown to depend on the type of ion and irradiation dose.     

Surface modification of PVDF membrane via AGET ATRP directly from the membrane surface

This contribution demonstrates a method for PVDF microporous membrane modification via surface-initiated activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) directly from the membrane surface. Three hydrophilic polymers, poly(2-(N,N-dimethylamino) ethyl methacrylate) (PDMAEMA), poly(2-oligo (ethylene glycol) monomethyl ether methacrylate) (POEGMA), and poly(2-hydroxyethyl methacrylate) (PHEMA), were grafted from the PVDF membrane surface in aqueous solution at room temperature. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the successful covalent tethering of the polymer chains onto the PVDF membrane surface. The gravimetry results indicated an approximately linear increase of the graft yields, up to about 330 μg/cm² for DMAEMA and 470 μg/cm² for both HEMA and OEGMA, with the polymerization time. Block copolymer brushes were prepared by chain extension. Water contact angle decreased over 50% for high yields, indicating improved surface hydrophilicity. The effects of the graft polymerization on membrane surface morphology, pore structure and permeability were investigated. It was found that the surface roughness was decreased and the pore size distribution was narrowed. The membrane permeability increased at low graft yields due to the enhanced hydrophilicity and decreased at high graft yields due to the overall reduction of the pore diameters.     

Ion-beam formation of electrocatalysts for fuel cells with polymer membrane electrolyte

Active layers of electrocatalysts are prepared by the ion-beam assisted deposition (IBAD) of platinum onto carbon-based AVCarb® Carbon Fiber Paper P50 and Toray Carbon Fiber Paper TGP-H-060 T supports and Nafion® N 115 polymer membrane electrolyte in the mode where the deposited metal ions are used as ions assisting the deposition process. Metal deposition and mixing of the deposited layer with the substrate under an accelerating voltage of 10 kV by the same metal ions are carried out from a neutral fraction of metal vapor and the ionized plasma of a pulsed vacuum-arc discharge, respectively. The composition and microstructure of the surface layers obtained are studied by Rutherford backscattering spectrometry (RBS), scanning electron microscopy (SEM), electron-probe microanalysis (EPMA), and X-ray fluorescence (XRF) analysis. The platinum concentration in the layers is (0.5–1.5) × 10¹⁶ at/cm². The prepared electrocatalysts exhibit activity in the process of the electrochemical oxidation of methanol and ethanol, which form the basis for the principle of operation of low temperature fuel cells (direct methanol fuel cells (DMFC) and direct ethanol fuel cells (DEFC)).     

Improving separation capability of regenerated cellulose ultrafiltration membrane by surface modification

In this study we introduced dialdehyde groups to a commercial regenerated cellulose (RC) ultrafiltration membrane by periodate oxidation. They were further converted to nitrogen-containing derivatives by Schiff base reaction with diethylenetriamine (DETA). The modified membrane was challenged with aqueous solution containing Pb(II) metal ions. The different variables affecting the rejection of lead ion by membrane including oxidization time, concentration of DETA, initial metal ion concentration and pH of the solution were elucidated. The membranes were characterized by FTIR-ATR, SEM, EDAX and elemental analyses. The process efficiency was enhanced by improving the oxidization time up to a certain period. In our case this was diminished after 9 h due to deterioration in the membrane integrity. The Pb²⁺ removal was facilitated by increasing feed pH and DETA concentration. This was diminished for more concentrated metal ion in the feed. Membrane regeneration was successfully utilized using 0.1 M HNO₃ solution. The removal capability of the regenerated membranes was maintained even after four cycles.     

Ion-beam reduction of the surface of higher oxides of molybdenum and tungsten

The process of reduction of the surface of oxides MoO₃ and WO₃ under irradiation by Ar⁺ and O ₂ ⁺ ions with an energy of 3 keV in high vacuum is investigated by X-ray photoelectron spectroscopy. It is shown that upon irradiation by Ar⁺ ions, lower and intermediate oxides and unoxidized metals are formed in the surface layers of higher oxides. Irradiation by O ₂ ⁺ ions mainly leads to formation of intermediate oxides with an insignificant content of lower oxides. It is found that the process of ion-beam reduction of the surface of oxides MoO₃ and WO₃ substantially depends on the ion type, irradiation dose, and difference in energy of the metal-oxygen bond in oxides.     

Preparation of poly(2-chloroaniline) membrane and plasma surface modification

P2ClAn membranes were obtained from chemically synthesized poly(2-chloroaniline) (P2ClAn) by casting method. These membranes were cast from dimethyl formamide (DMF) and were in the undoped state. P2ClAn membranes were characterized by Fourier infrared spectroscopy and scanning electron microscopy. Measurements of water content capacity, membrane thickness and ion-exchange capacity of the cast membranes were carried out. P2ClAn membranes were treated by electron cylotron resonance (ECR) plasma for surface modification. Plasma treatment has been successfully utilized for improving the surface properties of P2ClAn membranes such as increasing pore diameters and number of pores for better anion or molecule transportation.     

Ion-beam formation of the active surface of methanol oxidation electrocatalysts on the tantalum substrates

The active surfaces of electrocatalysts are formed by the ion-beam-assisted deposition of one of the rare-earth metals and platinum onto tantalum substrates from a neutral vapor fraction and the vacuum-arc discharge plasma of a pulsed ion source. Deposited metal ions are used as agents to aid deposition. The composition and microstructure of the formed surface layers are investigated via scanning electron microscopy, electron probe microanalysis, electron backscatter diffraction, and Rutherford backscattering spectrometry. Electrocatalytic activity in the electrochemical oxidation of methanol, which underlies the operation of low-temperature fuel cells, is investigated via cyclic voltamperometry.     

Ion-beam sculpting time scales

A study of ion sculpting dynamics in SiO2 and SiN using periodically pulsed ion beams reveals material transport that depends strongly on the time structure of the pulsed beams. It is found that significant nanoscale matter transport can occur over second long time scales after the ion beam has been extinguished. A simple phenomenological model described the dynamics of ion beam sculpting in terms of two material time scales. The model accounts for the surprising observation of enhanced matter transport affected by pulsed ion beams over continuous ion beam exposure.     

Laser-induced surface modification of polystyrene

The modification induced in polystyrene (PS) by the ArF excimer laser radiation has been investigated. Various numbers of the laser pulses of the energies below the material ablation threshold were applied. Changes in the chemical composition of the PS surface layer were studied by the X-ray photoelectron spectroscopy (XPS). Analysis of the morphological changes in the polymer surface layer was performed via the atomic force microscopy (AFM). The contact angles of test liquids (water and diiodomethane) were measured with use of a goniometer while the surface energy (SE) was calculated by the Owens-Wendt method. It was found that the surface energy change was mainly affected by surface roughness caused by the laser radiation and that surface oxidation had not considerably contributed to this change. The increase in the SE was mostly due to its disperse component.     

Femtosecond laser-induced surface wettability modification of polystyrene surface

In this paper, we demonstrated a simple method to create either a hydrophilic or hydrophobic surface. With femtosecond laser irradiation at different laser parameters, the water contact angle (WCA) on polystyrene’s surface can be modified to either 12.7° or 156.2° from its original WCA of 88.2°. With properly spaced micro-pits created, the surface became hydrophilic probably due to the spread of the water droplets into the micro-pits. While with properly spaced micro-grooves created, the surface became rough and more hydrophobic. We investigated the effect of laser parameters on WCAs and analyzed the laser-treated surface roughness, profiles and chemical bonds by surface profilometer, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). For the laser-treated surface with low roughness, the polar (such as C—O, C=O, and O—C=O bonds) and non-polar (such as C—C or C—H bonds) groups were found to be responsible for the wettability changes. While for a rough surface, the surface roughness or the surface topography structure played a more significant role in the changes of the surface WCA. The mechanisms involved in the laser surface wettability modification process were discussed.     

Proton dose-dependent modification in track etching response in some polymers

In the present work, the effect of four different doses of 62 MeV protons, on the fission fragment track etching characteristics of two polymers, viz. polycarbonate (Makrofol-N (MFN)) and polyimide (PI) are studied by nuclear track technique. The bulk etch-rate of PI increased by around 30% at the highest proton dose, whereas the activation energy of etching remained almost constant for the same. A considerable increase in the bulk etch-rate of MFN was observed (75%) at the highest proton dose. The activation energy of etching of the fission fragment tracks in MFN was also found to be an inverse function of dose.     

Ion-beam induced mixing in Al-Ni

Ion beam induced mixing of Al-Ni has been studied using N ₂ ⁺ and Ar⁺ bombardment. High dose (4×10¹⁷ ions cm^–2) nitrogen bombardment was found to cause blister formation with no unambiguous evidence of mixing. However, using argon ions at elevated substrate temperatures (400–450 °C) led to extensive mixing of 2000 Å Al layers on Ni. The mixing mechanism is considered to be point defect mediated radiation enhanced diffusion with a possible contribution from cascade mixing and interfacial oxide layer breakdown during the initial stages of treatment.     

氧化物薄膜的离子束溅射沉积

用离子束溅射沉积的方法制备的TiO_2、ZrO_2薄膜的光吸收损耗明显降低,对其折射率、光吸收和抗激光损伤阈值等特性进行了分析.     

Ion-beam depth-profiling studies of leached glasses

Ion-beam depth-profiling was carried out on three different glasses leached (or hydrated) in deionized water using ¹H(¹⁹F, αγ)¹⁶O nuclear reaction, secondary ion mass spectrometry (SIMS), and sputter-induced photon spectrometry (SIPS) techniques. The depth-profiles show an interdiffusion mechanism in which the sodium ions in the glass are depleted and replaced by hydrogen (H⁺) or hydronium (H₃O⁺) ions from the solution. The leaching behavior does not show significant difference whether the glass surface is fractured or polished. Problems of mobile ion migration caused by ion bombardment and loss of hydrogen during analysis are discussed.     

Ion-beam studies of synthetic single-crystal diamonds

A surface layer of polished single-crystal diamond plates with the (100) orientation, which can be applied to planar high-frequency high-power microstructures, is investigated by means of ion-beam and X-ray methods. It is demonstrated that the diamond plates are characterized by a high degree of structural perfection and a low level of surface roughness.     

Laser induced modification of surface structures

The results on surface modification of materials of different structures; morphology, grain sizes, density and porosity by exposure to nanosecond laser light are given. Laser induced changes in their surface characteristics are presented. Surface layers of Si₃N₄, SiC dense ceramics and BN graphite and turbostratic pressed powders are studied by scanning electron microscopy to reveal the new nanostructures (nanowires or nanotubes) and new morphologies. A pronounced evolution in structure and grain size of BN graphite powders was demonstrated in laser processing layers.