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Variable energy positron beam with Doppler broadening spectroscopy (DBS) was used to investigate the depth-resolved defects formed by two fluencies of 130 keV N+ implanted in Semi Insulating (SI) 6H-SiC. The implanted ions induced damages near the surface and to a depth of 300 nm as simulated by SRIM analysis. Defects recovery, accumulation, and its behavior with two annealing temperatures were also considered. Defect types and its effect on annealing were analyzed from the changes in electron momentum and modeled as layers using variable energy positron fitting (VEPFIT) methods. Inclusion of electric field strength in the fitting procedure supported layer characteristics and the state of charge carriers. Di-vacancies, vacancy complexes observed in the damaged layers were agglomerated at the surface and tend to cure on annealing.

Tin oxide (SnO2) nanoparticles are synthesized at different molar concentrations by employing a surfactant-free hydrothermal process. The structural properties of the samples investigated using XRD analysis indicated that the synthesized SnO2 nanoparticles have pure crystalline phase with tetragonal crystal structure of P42/mnm space group. The surface morphology analyzed using SEM micrographs showed that the nanoparticles get agglomerated without any specific structure. Optical characterization using UV–visible and PL spectroscopic techniques indicated that the synthesized SnO2 nanoparticles have absorption in the ultraviolet region and emission in the visible region due to defect states. A weak room-temperature ferromagnetism (RTFM) exhibited by the nanoparticles has been observed from the analysis of magnetic parameters.

Aluminium substituted mesoporous KIT-6 materials were directly synthesized by hydrothermal method with different silica to aluminium ratios (Si/Al = 25, 50, 75, 100). These materials were obtained by using Pluronic P123 and n-butanol as a structure-directing agent and co-solvent respectively, under high acidic conditions. The prepared catalysts were characterized by small-angle XRD, ICP-AES, nitrogen sorption analysis, TGA, SEM, TEM, and XPS techniques. The characterization revealed that aluminium is mainly incorporated into the framework of KIT-6. The XRD patterns and TEM images of materials showed a highly ordered cubic Ia3d mesostructure. The incorporation of the aluminium was clearly evident from XPS and ICP-AES techniques. Further, the synthesized Al-KIT-6 catalysts were tested in the acylation of isobutylbenzene (IBB) with acetic anhydride (AA). The results revealed that Al-KIT-6 (25) was a prominent active catalyst due to silica to aluminium ratio than others. The catalytic reaction conditions were tuned to obtain a high selectivity of 4-isobutyl acetophenone (4-IBA) with high conversion of isobutylbenzene. Al-KIT-6 (25) showed a high conversion (72%) of isobutylbenzene and 94% selectivity of 4-isobutyl acetophenone.

The study is intended to investigate the low energy nitrogen ion implantation induced behavior and re-crystallization in semi-insulating 6H-SiC from surface to 5 µm, by Raman spectroscopy. The nature of defects accumulation related to the SiC bond breakages and re-crystallization on vacuum annealing were analyzed from the A1(LO) phonon mode and probed at successive depth from the surface. Variations on the asymmetrical A1(LO) peaks of as-implanted samples were made to order upon annealing, and the mode regained. The peak intensity variation of A1(LO) mode indicated the disorder accumulation. The identified damage depth was in good agreement with Stopping and Ranges of Ions in Matter (SRIM). The changes in Si-Si, deformed-Si-C, C-C vibrations and crystalline-SiC were used to explain the defect role in the implanted and annealed samples.

Wide band gap materials like ZnO are being studied due to their potential applications in various devices. Here, in this work, ZnO thin films have been prepared using magnetron sputtering technique. Scanning Electron Microscopy (SEM) studies show rough surface. Only partial coverage is obtained for lower thickness and the coverage increases to maximum at higher thicknesses. Rutherford backscattering spectrometry results show the interfacial diffusion at Si–ZnO interface. High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Diffraction (SAD) studies show the polycrystalline nature of the films. As the thickness increases, number of defects also increases. Presence of Moire fringes and planar defects have been discussed using Fourier filtered HRTEM images and their corresponding FFTs.

In this work, a system of embedded Ge nanoclusters (NCs) has been fabricated inside a thermally grown SiOx matrix via a low-energy ion-implantation technique. The low-energy ion-implantation technique gives the flexibility to choose the number of ions to be implanted and depth at which the ions to be placed below the SiOx surface. This can be achieved by choosing the proper fluence and energy. Thirty kilo electron volts Ge ions have been implanted into a SiOx matrix (thermally grown) on Si(100) substrate. Ge concentration has been varied by choosing three different fluences (2.5 × 1015, 5 × 1015 and 1 × 1016 ions cm−2). Further, ex situ annealing was carried at 800°C under an inert atmosphere. Fluence-dependent distribution of Ge NCs post-annealing has been explained using Raman spectroscopy, photoluminescence spectroscopy (PL), Rutherford backscattering spectrometry (RBS) and cross-sectional transmission electron microscopy (XTEM) analysis.

Vacancy type defect profiles of Al+ implanted Semi- Insulating (SI) 6H- SiC have been obtained using low energy positron beam Doppler broadening spectroscopy measurements. Al+ ions of 400 keV with fluence 1014, 1015 and 1016 ions/cm2 have been implanted at room temperature to produce donor concentration from 1018 to 1020 Al+/cm3. The increases in S – parameter vs. positron beam energy E indicates the production of vacancies type defects by implantation. The normalized S – parameter with pristine for implanted 6H- SiC samples confirms the production of di-vacancies (for 1014 and 1015 ions/cm2) and larger voids (for 1016 ions/cm2)..

Embedded structures in a crystalline substrate, endotaxial structures, play a major role in thermoelectric and optoelectronic applications. Here, we have fabricated Ge nanostructures inside Si(100) matrix via low-energy Ge+ ion implantation. Thermally grown SiO2 layer over the Si substrate has been used as a protective coating to avoid low-energy sputtering of the Si surface. 300 keV Ge ions are implanted into Si(100) matrix at two different fluences, 1 × 1015 and 5 × 1015 ions/cm2. After annealing the as-implanted specimens at 800 °C under the inert atmosphere for 1 h, the growth of Ge nanoclusters has been studied by Raman spectroscopy. Endotaxial nature of the Ge nanocrystals has been studied using cross-sectional high-resolution TEM. The compatibility between Ge and Si at the nanocrystal/matrix interface has been discussed in detail using high-resolution phase-contrast imaging.

Electron beam evaporated Mg doped ZrO2 (Mg:ZrO2) high-k thin films on p-type Si(100) substrate and their metal oxide semiconductor (MOS) capacitors were structurally and electrically studied. Thicknesses of the dielectric films were in the range from 85 to 240 nm with RMS roughness between 1.4 and 2.3 nm. The targets for e-beam evaporation were made with well characterized pure ZrO2 with monoclinic phase and with 3%Mg doped tetragonal phase stabilized ZrO2 nanopowders. Structural phase analysis revealed that the phases of Mg:ZrO2 thin films deposited have retained their respective phases of zirconia targets used. The incorporation of Mg ions in ZrO2 dielectric gate layer had increased the width of the hysteresis window in the C-V characteristics. Various leakage current conduction mechanisms in the accumulation region of the MOS capacitors have been used to understand the leakage current mechanism and found that traps present in the oxide layer played a major role in explaining the leakage current. In particular, the conduction mechanisms such as Poole-Frenkel emission, Space Charge Limited Conduction and Trap-assisted tunneling were found to be dominant in these devices. A high dielectric constant of 28.9 was achieved in the Mg doped tetragonal phase stabilized ZrO2 gate oxide films with a leakage current density of 3.32 × 10−6 A/cm2 at − 1 V. Hence, the tetragonal phase stabilized Mg:ZrO2 gate oxide layer showed improved electrical characteristics making them potential for memory storage devices.

The current paper identifies the mechanism of hardening of modified 9Cr–1Mo steel during 3 MeV proton irradiation and softening during healing treatment. The steel, when irradiated with 3 MeV protons to a dose of 0.14 dpa, showed a significant increase in hardness up to certain depth, followed by a decrease. The peak hardness appeared at a depth of 35–40 µm, which matched with the depth at which defect density was maximum as calculated using SRIM2003 code. Rietveld analysis of X-ray diffraction patterns from different depths confirmed that the defect density doubled at the subsurface after irradiation. Annealing the irradiated steel at 823 K for 30 min could partially reduce the defect density and hence, soften the steel.

We report the structure and electron field emission properties of ion beam reduced graphene oxide (GO). 500 keV Ar+ ion beam was used to reduce the GO, synthesized by modified Hummer’s method. X-ray photoelectron spectroscopy and Resonant Rutherford backscattering spectrometric analyses evidenced that the oxygen functional groups drastically reduced upon irradiation. Further, the ion beam reduced GO exhibits enhanced electron field emission property. The exponential reduction of oxygen concentration is correlated with the field enhancement factor. Raman studies shows that ion irradiation process does not introduced any additional defects in GO. Scanning electron microscopic analysis reveals layered structure of GO sheets upon ion irradiation. Our investigation demonstrated that ion beam irradiation of GO yields a highly enhanced field emission with low turn-on voltage without deteriorating its structure.

The influence of carbon concentration on the electronic and magnetic properties of C-implanted ZnO thin films has been studied using synchrotron radiation based X-ray absorption spectroscopic techniques and vibrating sample magnetometer measurements. 20 keV carbon ions were implanted in ZnO films with different fluences (2 × 1016, 4 × 1016 and 6 × 1016 ions per cm2). The pristine ZnO film shows diamagnetic behaviour while the C-implanted films exhibit room temperature ferromagnetism. Our first-principles calculations based on density functional theory show an appreciable magnetic moment only when the implanted C atom sits either in the O-site (2 μB) or in the interstitial position (1.88 μB), whereas the C atom in the Zn substitutional position does not possess any magnetic moment. X-ray absorption near edge structure analysis at the O K-edge reveals that the charge transfer from O-2p to the C-defect site causes the ferromagnetism in the C-implanted ZnO film at low fluence. However at high fluence, the implanted C replaces the lattice and produces more Zn vacancies, as evidenced by extended X-ray absorption fine structure studies at the Zn K-edge, which favors the ferromagnetism. The persistence of the implanted carbon and ferromagnetism of the C-implanted ZnO film has also been studied by isothermal annealing at 500 °C and discussed in detail.

This work aims to review the enhancement of electrical conductivity and field electron emission (FEE) properties of ultrananocrystalline diamond (UNCD) films as a function of gold ion implantation content. Au has been employed in UNCD films as an implanted species as well as an interlayer between diamond film and substrate. In the initial part of the review UNCD films are briefly introduced. The focus is on their FEE properties and multiple strategies employed for enhancing these properties using ion-implantation with the goal to obtain a better cathode material. A comparison of the characteristics of the UNCD films implanted with Au and other species after studying the modification of the microstructure and emission properties of the Au-implanted UNCD films is then provided. Subsequently, the use of a thin Au coating on silicon substrates covered by UNCD or hybrid granular structured diamond films is discussed. The Si diffusion through the Au-Si eutectic interface results in a SiC layer. This facilitates the nucleation of diamond clusters, thereby suppressing the development of the carbon layer which is amorphous and electrically resistive, resulting in improved FEE characteristics. Finally, in the third and final part, the combined effects of Au-ion implantation (including multi-energy Au ion implantation) and Au-interlayer is discussed. Based on the obtained results, the catalytic activity of gold for improving the electrical conductivity and the FEE properties of diamond films is highlighted.

There are contradictory theoretical predictions of lattice location of oxygen interstitial atom at tetrahedral and octahedral interstices in bcc Fe. For validating these predictions, 300 keV O18 ions with fluence of 5 × 1015 ions/cm2 are implanted into bcc Fe single crystals at room temperature and annealed at 400 °C. The Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA)/channeling measurements are carried out with 850 keV protons. The lattice location of implanted O18 is analysed using the α-particles yield from O18(p,α)N15 nuclear reaction. The tilt angular scans of α-particle yield along 〈110〉 and 〈100〉 axial directions are performed at room temperature. Lattice location of O18 is found to be at tetrahedral interstitial site by comparing the experimental scan with simulated scans using FLUX7 software.

The removal of hazardous anions is essential to supply safe drinking water. In this study mesoporous Fe2O3/TiO2 was synthesized by sol–gel route using Pluronic P123 as the structure directing agent. The synthesized mesoporous Fe2O3/TiO2 nanoparticles dispersed over the reduced graphene oxide, to suppress the aggregation of the nanoparticles and to expose more number of active sites present in the nanoparticles. The mesoporous nature of the nanoparticles was confirmed from low angle X-ray diffraction. The reduced graphene oxide supported Fe2O3/TiO2 nanoparticles was characterized by FT-IR, Raman, XPS, N2 sorption, HR-TEM and SEM. The reduced graphene oxide supported Fe2O3/TiO2 nanoparticles was tested for the sorption of both arsenate (AsV) and arsenite (AsIII) in water. The equilibrium adsorption was attained within 15 mins for both As(III) and As(V). The maximum adsorption capacity for As(V) and As(III) was found to be 99.5 and 77.7 mg/g at pH 6 and 7 respectively. The sorption was found to be high in the pH range of 6–7. The low adsorption at lower and higher pHs other than 6 and 7 was due to zero point charge of nanocomposite which is equal to 6. The IR spectrum showed characteristic vibrations for arsenate in the nanocomposite. The recyclability study of nanocomposite not only confirmed the stability but also exhibited same sorption capacity for four cycles. This nanocomposite could be used for the removal of other hazardous inorganic ions.

SnO 2 thin films were obtained by ex-situ oxidation of Sn metal film deposited by thermal evaporation. The oxidation of the Sn film was carried out at 600, 700 and 900 °C for 2 h in a controlled oxygen atmosphere. GIXRD confirmed the tetragonal rutile phase of SnO 2 which was further confirmed by Raman spectroscopy. The RBS measurements provided the thickness and chemical information of the film. Thickness of the film was in the range of 6⿿12 nm and the presence of Sn and oxygen in the films are shown. Scanning electron microscopy revealed spherical particles of different sizes for films annealed at different temperatures. The SnO 2 thin film oxidized at 900 °C was tested for methane gas sensing. A sensing response of 78.46% for 100 ppm of methane at an operating temperature of 100 °C which is one of lowest reported was obtained.

This paper presents the details of a personal computer (PC) based automation of ion beam analysis and ion implantation experimental setup that has been developed and implemented in a 1.7 MV Tandetron accelerator. Hardware and software of the PC automated system were designed to automate multiple sample ion implantation, standard Rutherford Backscattering spectrometry (RBS), and High resolution Rutherford Backscattering spectrometry (Hi-RBS) experiments. The system uses in-house developed signal conditioning circuitry, isolation amplifiers, and transistor drivers along with cost-effective and off-the-shelf commercial components like a general purpose, multifunction data acquisition card, etc. A five axis goniometer is used for handling multiple samples and their automatic positioning according to the commands from the PC over RS232 interface. Key tasks carried out in the automation of system include control and mesurement of ion beam fluence, selection of backscattered particles through screening of their energies by controlling a set of +/−25 kV and −3 kV high voltage power supplies, controlled collection of backscattered yield using single and multi channel analysers, controlling the region-of-interest windows in the energy spectra and the cumulative counts in them. Controlling the position of the samples and facilitating the experiments on multiple samples, online display of energy spectra and its auto storage, and vacuum interlocking are also automatically done. This PC based setup has been automated using a windows based LabVIEW software making it easy to port the set up between different computer operating systems apart from achieving many other advantages like quick and easy development of versatile, multi-purpose, and user friendly graphical interface. Extensive tests carried out on the hardware established correct functioning of various modules of the hardware. The 0–10 V control inputs applied to the +/−25 kV and −3 kV high voltage power supplies were tested and seen providing an

We report a simple method involving optimization of oxygen partial pressure (OPP) in the after-growth annealing process of MoOx nanostructured thin films that results in a better field emitter with a low turn-on field and a high field enhancement factor. A ≈250 nm thick molybdenum oxide thin film has been synthesized on Si(100) substrates by the physical vapor deposition technique. The as-deposited thin films are annealed at 600 °C for 30 min in different OPPs, such as ≈2.1 × 10−9 Pa, ≈2.1 × 10−1 Pa, and ≈2.1 × 104 Pa. The effect of postannealing on the morphology, crystal structure, stoichiometry, elemental concentration, optical and local work function of the samples has been investigated using scanning electron microscopy, atomic force microscopy, resonant Rutherford backscattering spectrometry, and X-ray diffraction methods. As-deposited amorphous thin films transformed to granular MoO2 and layeredlike α-MoO3 nanostructures after annealing at 600 °C for 30 min in the OPP of ≈2.1 × 10−9 Pa and ≈2.1 × 104 Pa, respectively. The optical bandgap and the local work function are increased from 2.60 eV to 3.22 eV and 5.12 eV to 5.76 eV, whereas the field emission turn-on field is decreased from 6.6 V/μm to 4.7 V/μm for 10 μA/cm2 with increasing OPP from ≈2.1 × 10−9 Pa to ≈2.1 × 104 Pa.

Continuous depth sensing nano-indentation hardness measurements coupled with low-energy positron beam Doppler broadening line shape measurements were performed to investigate the influence of vacancy defects on mechanical properties in as-dealloyed and Fe+ ion irradiated nanoporous Au. A linear relationship has been obtained from the actual data between the nano-indentation hardness and square root of the concentration of defects. It suggests that the vacancy-type defects that evolved in the ligaments play a significant role in the modification of mechanical properties in both as-dealloyed and Fe+ ion irradiated nanoporous Au. The results have been also compared with those obtained on bulk Au.

Ion beam irradiation technique has been proposed, for efficient, fast and eco-friendly reduction of graphene oxide (GO), as an alternative to the conventional methods. 5 MeV, Au+ ion beam has been used to reduce the free standing GO flake. Both electronic and nuclear energy loss mechanisms of the irradiation process play a major role in removal of oxygen moieties and recovery of graphene network. Atomic resolution scanning tunnelling microscopy analysis of the irradiated GO flake shows the characteristic honeycomb structure of graphene. X-ray absorption near edge structure analysis at C K-edge reveals that the features of the irradiated GO flake resemble the few layer graphene. Resonant Rutherford backscattering spectrometry analysis evidenced an enhanced C/O ratio of ~23 in the irradiated GO. In situ sheet resistance measurements exhibit a sharp decrease of resistance (few 100 s of Ω) at a fluence of 6.5 × 1014 ions cm−2. Photoluminescence spectroscopic analysis of irradiated GO shows a sharp blue emission, while pristine GO exhibits a broad emission in the visible—near IR region. Region selective reduction, tunable electrical and optical properties by controlling C/O ratio makes ion irradiation as a versatile tool for the green reduction of GO for diverse applications.

The impact of lithium-ion implantation and postannealing processes on improving the electrical conductivity and field electron emission (FEE) characteristics of nitrogen-doped nanocrystalline diamond (nNCD) films was observed to be distinctly different from those of undoped NCD (uNCD) films. A high-dose Li-ion implantation induced the formation of electron trap centers inside the diamond grains and amorphous carbon (a-C) phases in grain boundaries for both types of NCD films. Postannealing at 1000 C healed the defects, eliminated the electron trap centers, and converted the a-C into nanographitic phases. The abundant nanographitic phases in the grain boundaries of the nNCD films as compared to the uNCD films made an interconnected path for effectual electron transport and consequently enhanced the FEE characteristics of nNCD films. The authors would like to thank the financial support of the Research Foundation Flanders (FWO) via Research Grants 12I8416N and 1519817N, and the Methusalem "NANO" network. K.J.S. and P.P. are Postdoctoral Fellows of the Research Foundation Flanders (FWO). The Hercules Foundation Flanders is acknowledged for financial support of the Raman equipment.

We study the reduction of graphene oxide (GO) sheets, synthesized by modified Hummer’s method, using medium energy ion beams (500 keVAr+ or 500 keVN+). Resonant Rutherford backscattering spectrometry technique has been employed to quantify the oxygen reduction upon irradiation. Ion irradiation process results exponential reduction with the increase of fluence. The C/O ratio of Ar+ ion irradiated samples is larger than the N+ irradiated sample, indicating that Ar+ ion beam can be effectively used to reduce GO. The grazing incident X-ray diffraction analysis also reveals that the RGO content is enhanced in Ar+ ion irradiated sample in comparison with N+ irradiated sample.

Hybridization of gold nanoparticles in the ultrananocrystalline diamond materials improves the electrical conductivity of the materials to a high level of 230 (Ω cm)(-1) with a sheet carrier concentration of 8.9 × 10(20) cm(-2). These hybrid materials show enhanced electron field emission (EFE) properties, viz. a low turn-on field of 2.1 V μm(-1) with a high EFE current density of 5.3 mA cm(-2) (at an applied field of 4.9 V μm(-1)) and the life-time stability up to a period of 372 min. The fabrication of these hybrid materials with high conductivity and superior EFE behaviors is a direct and simple process which opens new prospects in flat panel displays and high brightness electron sources.

Resonant Rutherford backscattering spectrometry (RRBS) technique can be used for analysis and quantification of carbon in few layer graphene and graphene oxide films. The carbon concentration estimated using RRBS measurements satisfactorily agreed with the theoretically reported value. Our experimental studies evidenced that RRBS technique can be used for the analysis of carbon in graphene based material, particularly, RRBS with glancing incident angle with its high sensitivity can be effectively used for thickness and estimation of carbon concentration.

The field electron emission (FEE) properties of nitrogen-incorporated nanocrystalline diamond films were enhanced due to Li-ion implantation/annealing processes. Li-ion implantation mainly induced the formation of electron trap centers inside diamond grains, whereas post-annealing healed the defects and converted the a-C phase into nanographite, forming conduction channels for effective transport of electrons. This resulted in a high electrical conductivity of 11.0 S/cm and enhanced FEE performance with a low turn-on field of 10.6 V/mu m, a high current density of 25.5 mA/cm(2) (at 23.2 V/mu m), and a high lifetime stability of 1,090 min for nitrogen incorporated nanocrystalline diamond films. Published by AIP Publishing. The authors like to thank the financial support of the Research Foundation Flanders (FWO) via Research Projects 12I8416N and 1519817N, and the Methusalem "NANO" network. K. J. Sankaran and P. Pobedinskas are Postdoctoral Fellows of the Research Foundation-Flanders (FWO). The Hercules Foundation Flanders is acknowledged for financial support of the Raman equipment.

Positron depth profiling studies using variable positron beam were carried out to study the defect layer evolved in partially dealloyed Fe+ implanted Ag75Au25. Fe+ implantation to Ag75Au25 followed by partial dissolution leads to evolution of two distinct defect layer structures near to the surface of the corrosion region and the in the region close to the Fe+ implanted region.

Room temperature deposition of molybdenum-copper thin films have been performed by ion beam sputtering and characterized by x-ray diffraction, x-ray reflectivity, & Rutherford backscattering spectrometry studies. Electrical resistivity measurements were performed up to milli-Kelvin temperatures and residual resistivity ratio values have been calculated to figure out a correlation with copper thickness.Room temperature deposition of molybdenum-copper thin films have been performed by ion beam sputtering and characterized by x-ray diffraction, x-ray reflectivity, & Rutherford backscattering spectrometry studies. Electrical resistivity measurements were performed up to milli-Kelvin temperatures and residual resistivity ratio values have been calculated to figure out a correlation with copper thickness.

The effects of Cu and Au ion implantation on the structural and electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films were investigated. High electrical conductivity of 186 (Ω•cm)(-1) and enhanced EFE properties with low turn-on field of 4.5 V/μm and high EFE current density of 6.70 mA/cm(2) have been detected for Au-ion implanted UNCD (Au-UNCD) films that are superior to those of Cu-ion implanted UNCD (Cu-UNCD) ones. Transmission electron microscopic investigations revealed that Au-ion implantation induced a larger proportion of nanographitic phases at the grain boundaries for the Au-UNCD films in addition to the formation of uniformly distributed spherically shaped Au nanoparticles. In contrast, for Cu-UNCD films, plate-like Cu nanoparticles arranged in the row-like pattern were formed, and only a smaller proportion of nanographite phases along the grain boundaries was induced. From current imaging tunneling spectroscopy and local current-voltage curves of scanning tunneling spectroscopic measurements, it is observed that the electrons are dominantly emitted from the grain boundaries. Consequently, the presence of nanosized Au particles and the induction of abundant nanographitic phases in the grain boundaries of Au-UNCD films are believed to be the authentic factors, ensuing in high electrical conductivity and outstanding EFE properties of the films.

A novel magnetic Fe3O4 core-shell nanorods (MCSNs) were synthesized by crosslinking amine functionalized Fe3O4@SiO2 core-shell nanoparticles with 1,2-bromochloroethane. These nanorods were then protonated with dilute HCl. The MCSNs nanorods were characterized using FT-IR, N2 adsorption, VSM, SEM and TEM. The surface area of MCSNs nanorods was found to be 335 m2/g, which is higher than bare iron oxide and amine functionalized Fe3O4@SiO2. These nanorods were used simultaneously as ion-exchanger and adsorbent for the removal of arsenic from aqueous solution. It exhibited high adsorption capacity for arsenic. The kinetic study revealed that adsorption equilibrium attained within five min. The adsorbed arsenic on the nanorods were removed by magnetic separation and regenerated by acid treatment. The percentage removal of arsenic was more than 99%. Such nanorods can be used to remove not only arsenic but also other anions from potable water.

Efficient visible-light active mesoporous Ce incorporated TiO2 nanoparticles have been prepared by sol-gel method using Pluranic P123 as the structure directing agent. Low angle XRD and BET analysis revealed the mesoporous nature of the nanoparticles. The incorporation of Ce4+ into TiO2 and Ti4+ into CeO2 is evident from the slight shift in their respective XRD patterns. XPS results exhibited +4 oxidation state for Ce and Ti ions. UV-DRS analysis of Ce incorporated TiO2 demonstrated red shift in the absorbance spectrum of TiO2, which is mainly due to the formation of Ce impurity states below the conduction band edge of TiO2. The photocatalytic activity of mesoporous Ce incorporated TiO2 nanoparticles has been evaluated in the degradation of 4-chlorophenol in aqueous solution under solar light illumination. Pure mesoporous TiO2 showed poor visible-light activity due to its small absorption of sun light. Mesoporous Ce incorporated TiO2 photocatalysts exhibited the highest photocatalytic activity compared to pristine mesoporous TiO2 and CeO2. The incorporation of Ce4+ in TiO2 played a major role in the enhancement of photocatalytic activity under sun light.

Tribological properties of ultra nanocrystalline diamond (UNCD) films have chemically been modified by N + ion implantation and subsequent annealing processes. Friction coefficient is found to be 0.15 in as-prepared film comparing to 0.09 and 0.05 in N + ion implanted and post-annealed films, respectively. Such a modification of friction coefficient is a characteristic of the transformation of sp 3 to graphitized/amorphized sp 2 bonded carbon network. Transformation of sp 3 to sp 2 carbon network causes conversion of higher surface energy state (hydrophilic) to lower (hydrophobic) one which results in ultra low friction coefficient. Graphitization/amorphization in wear track observed by micro Raman spectroscopy is found to be the prominent mechanism for the reduction in friction coefficient.

It was reported that non-amorphizing implantation by hydrogen has a potential in improving silicon machining. Post-implantation high-temperature treatment will affect implantation-induced damage, which can have impact on silicon machining. In this article, a relation of a thermal annealing of hydrogen implanted in silicon to micro-cutting experiment is investigated. Hydrogen ions were implanted into 4″ silicon wafers with 175 keV, 150 keV, 125 keV and doses of 2 × 1016 cm−2, 2 × 1016 cm−2 and 3 × 1016 cm−2, respectively. In this way, low hydrogen atom–low defect concentration was created in the region less than ~0.8 μm deep and high hydrogen atom–high defect concentration was obtained at silicon depth of ~0.8–1.5 μm. The post-implantation annealing was carried out at 300 and 400 °C in nitrogen for 1 h. Physical and electrical properties of implanted and annealed samples were characterized by secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), Rutherford backscattering (RBS) and nanoindentation. Plunge cutting experiment was carried out in and silicon crystal direction. The critical depth of cut and cutting force were monitored and found to be influenced by the annealing. The limits of hydrogen implantation annealing contribution to the cutting characteristics of silicon are discussed in light of implantation process and redistribution of hydrogen and defects generation during annealing process.

Multienergy Au-ion implantation enhanced the electrical conductivity of heterogranular structured diamond films grown on Au-coated Si substrates to a high level of 5076.0 (Omega cm)(-1) and improved the field electron emission (FEE) characteristics of the films to low turn-on field of 1.6 V/mu m, high current density of 5.4 mA/cm(2) (@ 2.65 V/mu m), and high lifetime stability of 1825 min. The catalytic induction of nanographitic phases in the films due to Au-ion implantation and the formation of diamond-to-Si eutectic interface layer due to Au-coating on Si together encouraged the efficient conducting channels for electron transport, thereby improved the FEE characteristics of the films. Published by AIP Publishing. The authors would like to thank the financial support of Ministry of Science and Technology, Taiwan through the Project Nos. MOST 104-2112-M-032-003. K. J. Sankaran is a Postdoctoral Research Fellow of the Research Foundations-Flanders (FWO).

Vertically aligned TiO2-δ and TiO2–3yN2y nanotube array thin films were synthesized electrochemically in a single step. N-Doping at different levels was achieved by using different concentrations of urea, as nitrogen precursor, in the electrolyte. The GIXRD and Raman studies revealed that the nanotube arrays are of anatase phase. The field emission measurements showed low turn-on fields of 10, 9.21, and 6.54 V/μm at 3.88, 4.12, and 4.74 at% of N-doping, respectively, implying enhanced field emission upon N-doping as well as an increase in electron emission with increase in N-doping. The electron emission current was found to be stable for a period of 5 h. The high electron emission current and low threshold field on N-doping is due to the presence of localized donor states below the conduction band minimum, as a result of oxygen vacancies, created by N-doping, and introduction of localized N 2p states above the valence band minimum by the doped nitrogen .

Growth of Ag films on Br- and H-passivated Si(111) surfaces and the annealing behaviour have been investigated by Rutherford backscattering spectrometry, scanning electron microscopy and photoemission electron microscopy techniques. Upon annealing the phenomenon of thermal grooving was observed in the Ag films. Depending on the annealing temperature, at an intermediate annealing time Ag depletion (evaporation) from the grain boundaries produces fractal patterns of Ag-depleted regions. Continued annealing eventually produces a percolated network of Ag-depleted regions (thermal grooves) along the grain boundaries and isolated Ag grains appear as the depth of the grooves reaches the substrate. For the fractal structures produced by thermal grooving, the fractal dimension has been estimated to be 1.60 ± 0.04. Observation of a fractal pattern in thermal grooving was not hitherto reported. A thorough analysis of the experimental results has been carried out in the context of current theories. These theories are inadequate to describe the experimental results.

Thin films of TiO2−x and TiO2−x−yN2y nano-platelets having better field emission properties compared to one dimensional nanostructures reported in literature were synthesized by spray pyrolysis. Low threshold field of 8 V μm−1 and 4.1 V μm−1, for 1 mA cm2, was observed for TiO2−x and TiO2−x−yN2y respectively, implying enhanced field emission upon N-doping.

Nano-crystalline diamond coatings were deposited on the silicon substrate using Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD). Experiments were performed by varying the H2 content in CH4/H2 plasma during synthesis. Raman spectral analysis revealed that with decrease in hydrogen content in the CH4 plasma, the ID/IG ratio decreases with the formation of smaller crystallites. Such a film possesses a large grain boundary fraction containing hydrogenated amorphous carbon (a-C:H). During tribological test, sufficient amount of hydrogen present in the grain boundary passivates the dangling σ-bond causing ultra-low friction and extremely low wear evident by improvement in microstructure.

We report the structural evolution of reduced graphene oxide (rGO) in graphene oxide (GO) flakes during 1 MeV Si+ ion irradiation. In-situ electrical resistivity measurements facilitate monitoring the sheet resistance with the increase in the fluence. The electrical sheet resistance of the GO flake shows the exponential decay behaviour with the increasing ion fluence. Raman spectra of the GO flake reveal the increase in the ID/IG ratio, indicating restoration of the sp2 network upon irradiation. The C/O ratio estimated from resonant Rutherford backscattering spectrometry analysis directly evidenced the reduction of oxygen moieties upon irradiation. C K–edge X-ray absorption near edge structure spectra reveal the restoration of C=C sp2–hybridized carbon atoms and the removal of oxygen-containing functional groups in the GO flake. STM data reveal the higher conductance in the rGO regime in comparison with the regime, where the oxygen functional groups are present. The experimental investigation demonstrates...

International audience; We have prepared germanium nanoparticles embedded in SiO2 matrix by atom beam co-sputtering (ABS) of Ge+SiO2 on Si substrate. The as-deposited films were annealed at various temperatures in Ar+H2 atmosphere and irradiated with various energies with fixed fluence. The pristine and irradiated samples were characterized by Raman, X-ray diffraction and atomic force microscopy (AFM). Rutherford back scattering (RBS) was used to quantify the concentration of Ge in the SiO2 matrix and the film thickness. Raman studies of the films indicate the formation of Ge crystallites as a result of swift heavy ion (SHI) irradiation. Moreover, the crystalline nature of Ge improves with an increase in energy. Glancing angle X-ray diffraction and Raman results also confirm the presence of Ge crystallites in the irradiated samples. Similarly, 400keV Ge+ ions implanted into silicon substrate at higher fluence at 573K have been irradiated with 100MeV Au8+ions at RT. These irradiated implanted samples were subsequently characterized by XRD and Raman to understand the crystallization behavior. We also studied the surface morphology of a high-energy irradiated sample by AFM. The irradiation results were compared with those obtained by thermal annealing in ABS. The basic mechanism for crystallization induced by SHI in these films has been investigated.

Diamond like carbon (DLC) films were deposited at room temperature on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) process using plasma of methane diluted with argon gas. During deposition, dc self bias (− 25 V to − 200 V) on substrate was varied by application of RF power to the substrate. The influence of substrate bias on density of the deposited films was studied by X-ray reflectivity (XRR). The results from these measurements are further correlated with the results from UV and visible Raman spectroscopy. DLC film is modeled as a structure having three different layers such as low density surface, bulk and interface with the substrate. This three-layer model is used to fit the measured XRR data to evaluate the surface, interface and interlayer roughness, thickness and density of these films. The surface roughness obtained from XRR is correlated with the results from Atomic Force Microscopy (AFM) measurements. The observed results are explained based on the subplantation model for DLC film growth.

The high-energy and heavy-ion induced sputtered particles from nanostructures under various conditions can result in variety of size distributions. 1.5 MeV Au2+ ions induced sputtering from isolated gold nanostructures deposited on silicon substrate have been studied as a function of incident ion flux (dose rate) and the sputter particle catcher at low temperature. At higher fluxes, a bimodal distribution of the sputtered particles has been observed. Cross-sectional transmission electron microscopy and Rutherford backscattering spectrometry measurements showed that the sputter particle size distribution depends on morphology at surface and interfaces. The results for the size distribution from a catcher at low temperature showed the less agglomeration of ejected clusters on the catcher grids, resulting in the lower-disperse size distribution.

Germanium atomic (Ge1) and molecular ions (Ge2) of equivalent energy are implanted in silicon at an elevated temperature. The ion induced damage has been characterized by RBS channeling (RBS/C) and positron annihilation spectroscopy. The RBS/C studies indicate that the molecular ion implantation has produced more defects in the near surface regions compared to the atomic ion implantation. This paper reports a first time observation of an enhanced production of vacancy related defects in silicon implanted with molecular ions.

Metal nanocluster composite glasses (MNCGs) have been the subject of both experimental and theoretical investigation because of their peculiar optical properties. In particular, the enhanced third order optical nonlinearity could be exploited in the all-optical switching device technology. In the present work, we present some results on MNCG films prepared by ion implantation. Fused silica were implanted with Au + of fluences 3 � 10 16 and 1 � 10 17 ions/cm 2 using an energy of 1.5 MeV. Optical absorption spectra of these samples have revealed prominent linear absorption bands at characteristic surface plasmon resonance (SPR) wavelength at and around 490 nm. Rutherford backscattering spectrometry (RBS) measurements reveal a Gaussian spatial distribution of Au ions. Third order optical nonlinear properties were studied by the Z-scan technique using a nanosecond laser. Z-scan measurements on the metal nanoclusters glass composites have revealed saturable absorption signifying the nonlinear responses. � 2007 Elsevier B.V. All rights reserved.

Recently, interesting differences for ion – uniform film and ion – nanostructure interaction phenomena, particularly relating to ion beam mixing effects have been reported. Upon irradiation with 1.5 MeV Au 2+ ions on isolated Au nanostructures on silicon substrate, a higher probability of crater formation, larger sputtered particle size and its coverage and enhanced sputtering yield compared to the continuous films of Au on Si substrate were observed. Ion bombardment at high flux (≈6.3 × 10 12 ions cm −2 s −1 ) showed a dramatic mass transport from nanostructures extending up to a distance of about 60 nm into the substrate, much beyond their size. In this paper, RBS/Channeling results would be presented to elucidate on the arrangement of re-distributed gold atoms location in silicon and silicide matrix. Scanning transmission electron microscopy (STEM, with high angle annular dark field imaging) was used to complement the RBS results in determining the unusual mass transport and under ion–nanostructure interaction. The amorphous nature of the silicon matrix, that is deduced from both the RBS/Channeling and from TEM measurements, is an important factor in enhanced diffusion process resulting in dramatic mass flow.