Modifications induced by silicon and nickel ion beams in the electrical conductivity of zinc nanowires

This paper presents the modification in electrical conductivity of Zn nanowires under swift heavy ions irradiation at different fluences. The polycrystalline Zn nanowires were synthesized within polymeric templates, using electrochemical deposition technique and were irradiated with 80 MeV Si⁷⁺ and 110 MeV Ni⁸⁺ ion beams with fluence varying from 1 × 10¹² to 3 × 10¹³ ions/cm². I–V characteristics of exposed nanowires revealed a decrease in electrical conductivity with increase in ion fluence which was found to be independent of applied potential difference. But in the case of high fluence of Ni ion beam (3 × 10¹³ ions/cm²), electrical conductivity was found to increase with potential difference. The analysis found a significant contribution from grain boundaries scattering of conduction electrons and defects produced by ion beam during irradiation on flow of charge carriers in nanowires.     

Ion implantation effects of negative oxygen on copper nanowires

Copper nanowires of diameter 80 nm were synthesized in polycarbonate membrane using template technique. Samples were then implanted with 160 keV O^?1 ion beam with varying particle fluence of 1?×?10¹², 5?×?10¹² and 1?×?10¹³ ions/cm². The SRIM (Stopping and range of ions in matter) software was used to study the processes involved. Compositional analysis confirms implantation of oxygen ions and the stoichiometry of Cu:O was found to be 6:1 by weight % when implanted at 1?×?10¹³ ions/cm². Scanning electron microscopy reveals no changes in morphology of nanowires on implantation. X-ray diffraction analysis showed no shifting in the ‘2θ’ position of diffraction peaks however some new diffraction peaks of oxygen were seen. Implantation with oxygen ion led to the increased crystallite size and reduced strain. The conductivity of the nanowires was found to increase linearly with the ion fluence presenting constructive effect of negative ion implantation on copper nanowires.     

Measurement of the Diffusion Coefficient of Water in RP-3 and RP-5 Jet Fuels Using Digital Holography Interferometry

The diffusion coefficient of water in jet fuel was measured employing double-exposure digital holographic interferometry to clarify the diffusion process and make the aircraft fuel system safe. The experimental method and apparatus are introduced in detail, and the digital image processing program is coded in MATLAB according to the theory of the Fourier transform. At temperatures ranging from 278.15 K to 333.15 K in intervals of 5 K, the diffusion coefficient of water in RP-3 and RP-5 jet fuels ranges from 2.6967?×?10 ^?10 m²·s^?1 to 8.7332?×?10 ^?10 m²·s^?1 and from 2.3517?×?10 ^?10 m²·s^?1 to 8.0099?×?10^?10 m²·s^?1, respectively. The relationship between the measured diffusion coefficient and temperature can be well fitted by the Arrhenius law. The diffusion coefficient of water in RP-3 jet fuel is higher than that of water in RP-5 jet fuel at the same temperature. Furthermore, the viscosities of the two jet fuels were measured and found to be expressible in the form of the Arrhenius equation. The relationship among the diffusion coefficient, viscosity and temperature is analyzed according to the classic prediction model, namely the Stokes–Einstein correlation, and this correlation is further revised via experimental data to obtain a more accurate predication result.     

Development of a Compact Electrostatic Nanoparticle Sampler for Offline Aerosol Characterization

A compact electrostatic nanoparticle sampler has been developed to support the offline analysis of nanoparticles via electron microscopy. The basic operational principle of the sampler is to electrically charge particles by mixing nanoparticles and unipolar ions produced by DC corona discharge, and electrostatically collecting charged particles. A parametric study was first performed to identify the optimal operating condition of the sampler: a total flow rate (i.e., the sum of the particle and ion carrier flow rates) of 1.0 lpm, an aerosol/ion carrier flow rate ratio of 1.0, and a collection voltage of 4.5 kV. Under the above condition, the sampler achieved a collection efficiency of more than 90 % for particles ranging from 50 to 500 nm. The effect of particle material on the sampler’s performance was also studied. The prototype had lower collection efficiencies for oleic acid particles than for sodium chloride particles in the size range from 50 to 150 nm, while achieving a comparable efficiency in the size range large than 150 nm. Effects of particle diameter, particle material, and total flow rate on the sampler’s collection efficiency are explained by the particle charging data, i.e., charging efficiencies and average charges per particle.     

Synthesis of zirconium silicide in Zr thin film on Si and study of its surface morphology

Zirconium silicide was synthesized on Si (100)/zirconium interface by means of swiftly moving 150 MeV Au ion beam. Thin films of zirconium (~60 nm) were deposited on Si (100) substrates in ultra high vacuum conditions using the electron-beam evaporation technique. The system was exposed to different ion fluencies ranging from 3 × 10¹³ to 1 × 10¹⁴ ions/cm² at room temperature. Synthesized zirconium silicide thin film reasonably affects the resistivity of the irradiated system and for highest fluence of 1 × 10¹⁴ ions/cm² resistivity value reduces from 84.3 to 36 μΩ cm. A low resistivity silicide phase, C-49 ZrSi₂ was confirmed by X-ray analysis. Schottky barrier height was calculated from I–V measurements and the values drops down to 0.58 eV after irradiation at 1 × 10¹⁴ ions/cm². The surface and interface morphologies of zirconium silicide were examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM shows a considerable change in the surface structure and SEM shows the ZrSi₂ agglomeration and formation of Si-rich silicide islands.     

Band offset diagnostics of advanced dielectrics

We present a non-contact electrical metrology of advanced dielectrics on silicon with an emphasis on monitoring the composition of mixed dielectrics such as oxynitrides and hafnium silicates. The approach takes advantage of significant band offset differences between individual components of the mixed dielectrics. To maximize the sensitivity to the band offset, the measurement is done in a tunneling range under the Self-adjusting steady state (SASS) condition. Such a condition is obtained when a corona charging pulse induces a tunneling current through the dielectric that matches the ionic charging current. Positive corona is used to probe the conduction band offset, while negative corona is used to probe the valence band offset. The key measured parameter is the dielectric voltage under the SASS condition. It is measured with a commercial corona–Kelvin tool, with macro-(mm²) and micro-(30 × 30 μm²) charging and monitoring capability. The dielectric surface potential is measured with a vibrating Kelvin-probe. Modeling of the tunneling current is used to illustrate the principle of the approach and to support the pertinent SASS equations. The method is applied to a skew of SiON mixed dielectrics on p-Si.     

Comparison between an unipolar corona charger and a polonium-based bipolar neutralizer for the analysis of nanosized particles and biopolymers

In this work we present results on the charging efficiency of nanoparticles by means of a corona based unipolar charging unit. This device was designed to replace a Po210 bipolar charger unit in a commercial electrospray aerosol generator (TSI Mod 3480). The charging efficiency has been investigated for negative and positive charged particles of various chemical composition in the size range between 5 and 18 nm. The corona current has been found to be the most influential operation parameter on the charging efficiency. With a positive electrospray droplet charge and a negatively-biased corona needle, a rapidly decreasing yield of singly positively charged aerosol particles with increasing corona current was found. An increasing yield of negatively charged particles was observed with increasing current of the corona process. Providing appropriate corona settings nanoparticles with charge levels similar to these obtained with a Po210 charger were found. At optimal corona settings the yield of singly charged particles was found to be two to four times higher for negative and positive particles compared to bipolar charging. This gain in the charging efficiency increases directly the sensitivity of analysis and enhances all measurement and manipulation processes of airborne nanoparticles for which electrical charging is required.     

Swift heavy ion induced structural,optical and luminescence modification in NaSrBO3:Dy3+ phosphor

The effect of 120 MeVAg⁹⁺ ion irradiation on the structural, optical and luminescence properties of NaSr_1-xBO₃:xDy³⁺ (x = 0.5–2.5 mol%) phosphor synthesized by the conventional solid state reaction route is reported. The samples were irradiated with Ag⁹⁺ swift heavy ions (SHIs) using fluences of 1 × 10¹², 5 × 10¹² and 1 × 10¹³ ions cm^?2. The unirradiated as well as irradiated samples were characterized by powder X-ray diffraction (PXRD), diffuse reflectance (DR) and photoluminescence techniques. PXRD confirms no change in the phase after irradiation except that loss of crystallinity had been observed which may be due to the fragmentation caused by the SHI. A blue shift in the absorption band of the DR was observed, resulting in an increase in the band gap from 5.61 eV to 5.77 eV, after ion irradiation. An increase in photoluminescence intensity (excited at 385 nm) was observed with increased ion fluences. The ratio of the blue to yellow emission peaks (I₄₈₃/I₅₇₇) was calculated and found to be varying with ion fluences suggesting that the white light can be achieved by tailoring this yellow to blue ratio. The Commission Internationale de l’Eclairage coordinates were calculated and found to move toward the white region after irradiation.     

Charge and mass transfer in the cathode plasma jet of a low-inductance vacuum spark

The contributions of fast and slow ion components to the average mass transfer rate in the cathode plasma jet of a low-inductance vacuum spark have been determined using time-of-flight measurements. The total mechanical momentum of the cathode plasma jet has been found using the ballistic pendulum technique. The coefficient γ of ion erosion of a cathode material was evaluated in the range of discharge current amplitudes 3–13 kA and the discharge current buildup rates 4 × 10⁹ − 1.5 × 10¹⁰ A/s. The γ value exhibits small variations in the indicated range of discharge parameters and is close to the values known for vacuum arcs.     

Swift heavy ion irradiation induced modification of structure and surface morphology of BiFeO3 thin film

BiFeO₃ (BFO) thin films of thickness about 800 nm deposited on Si (100) substrates by sol–gel spin coating method were irradiated by 200 MeV Ag ions. Modification of structure and surface morphology of the films under irradiation was studied using glancing incidence X-ray diffraction (GIXRD) and atomic force microscope (AFM). Fluence dependence of GIXRD peak intensity indicated formation of 10 nm diameter cylindrical amorphous columns in crystalline BFO due to 200 MeV Ag ion irradiation. AFM analysis indicated that the pristine film consists of agglomerated grains with diffuse grain boundary. Irradiation led to reduced agglomeration of the grains with the formation of sharper grain boundaries. The rms roughness (σ _rms) estimated from AFM analysis increased from 6·2 in pristine film to 12·7 nm when the film irradiated at a fluence of 1 × 10¹¹ ions cm ^???2 . Further irradiation led to decrease of σ _rms which finally saturated at a value of 7–8 nm at high ion fluences. The power spectral density analysis indicated that the evolution of surface morphology of the pristine film is governed by the combined effect of evaporation condensation and volume diffusion processes. Swift heavy ion irradiation seems to increase the dominance of volume diffusion in controlling surface morphology of the film at high ion fluences.     

Structure transition and multiferroic properties of Mn-doped BiFeO3 thin films

Pure BiFeO₃ (BFO) and Mn-doped BiFe_1?yMn_yO₃ thin films were prepared on FTO/glass (SnO₂: F) substrates by using a sol–gel method. The effects of Mn-doping on the structure and electric properties of the BFO thin films were studied. The X-ray diffraction (XRD) analysis reveals a structure transition in the Mn-doped BiFe_0.96Mn_0.04O₃ (BFMO) thin film. The Rietveld refined XRD patterns conform the trigonal (R3c: H) and tetragonal (P422) symmetry for the BFO and BFMO thin films, respectively. The structure transition and the mixed valences of Mn ions substantially improve the electric properties of the BFMO thin film. The remnant polarization (P _r) of the BFMO thin film was 105.86 μC/cm² at 1 kHz in the applied electric field of 865 kV/cm. At an applied electric field of 150 kV/cm, the leakage current density of BFMO thin film is 1.42 × 10^?5 A/cm². It is about two orders of magnitude lower than that of the pure BFO thin film (1.25 × 10^?3 A/cm²). And the enhanced saturated magnetization of the BFMO thin film is 4.45 emu/cm³.     

Irradiation effects on AlGaN HFET devices and GaN layers

AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with protons as well as carbon, oxygen, iron and krypton ions of high (68 and 120 MeV) and low (2 MeV) energy with fluences in the range from 1 × 10⁷ to 1 × 10¹³ cm^?2. High energy irradiation with protons, carbon and oxygen produced no degradation in devices while krypton irradiation at the fluence of 1 × 10¹⁰ cm^?2 resulted in a small reduction of 2% in the transconductance. Similarly, for GaN samples irradiated with protons, carbon and oxygen at high energy no changes were seen by XRD, PL and Hall effect, while changes in lattice constant and a reduction in PL intensity were observed after irradiation with high energy krypton. Low energy irradiation with carbon and oxygen at a fluence of 5 × 10¹⁰ cm^?2 results in small change in the device performance while remarkable changes in device characteristics are seen at a fluence of 1 × 10¹² cm^?2 for carbon, oxygen, iron and krypton irradiation. Similarly changes are also observed by XRD, PL and Hall effect for the thick GaN layer irradiated at the fluence of 1 × 10¹² cm^?2. The device results and GaN layer properties are strongly correlated.     

Electronic excitation induced phase transformation in FSMA thin film

The influence of 120 MeV Ag ion irradiation on the structural and magnetic properties of Ni–Mn–Sn ferromagnetic shape memory alloy thin film is investigated. X-ray diffraction data confirms the phase transformation from martensite to austenite phase at a fluence of 1 × 10¹³ ions/cm², which is further supported by the change in surface morphology of the film with increasing fluence as evidenced by field emission scanning electron microscopy. Thermo-magnetic measurements reveal the increase in magnetization and decrease in phase transformation temperatures with increasing fluence. The maximum value of magnetization is ∼2.9 × 10⁵ Amp/meter for the film irradiated at a fluence of 1 × 10¹³ ions/cm². The results are explained on the basis of thermal spike model considering the core and halo regions of ion tracks in FSMA materials.     

Design and characteristics of HTSC SQUID magnetometer with a sensitivity of 10−13 THz−1/2

The results are presented of the experimental studies on forming weak links in yttrium ceramics by scribing and high-voltage discharge. The energy resolution of SQUIDs and the magnetic field sensitivity of magnetometers produced according to these methods were 6×10⁻²⁸ J/Hz and 10⁻²⁸ J/Hz, 5×10⁻¹³ T/Hz^1/2 and 2·5×10⁻¹³ T/Hz^1/2, respectively. Different designs of HTSC interferometers sensitive to the external magnetic field variation are described. The factors affecting the sensitivity of r.f. HTSC SQUID-magnetometers are considered.     

Multi-emitter field ion source based on a nanostructural carbon material

A new multi-emitter field ion source based on a nanostructural carbon-based composite has been developed. The coefficient of electric field enhancement at the emitter surface reaches 6.5 × 10⁴. The emitter surface shaped by means of low-temperature field evaporation ensures a substantially increased homogeneity of the field ion emission.     

Removal of nickel from electroplating rinse waters using electrostatic shielding electrodialysis/electrodeionization

Electrostatic shielding zones made of electrode graphite powder were used as a new type of ionic and electronic current sinks. Because of the local elimination of the applied electric field, voltage and current within the zones, ions are led inside them and accumulate there. The current sinks were implemented in electrostatic shielding electrodialysis of a simulated nickel plating rinse water containing 100 mg L^?1 nickel and electrodeionization of a 0.001 M NiSO₄ solution with simultaneous electrochemical regeneration of the ion exchange resin beds. Pure water was obtained with a Ni²⁺ ion concentration of less than 0.1 mg L^?1 at a flow rate of 2.02 × 10^?4 dm³ s^?1 diluate stream and a current density of 30 A m^?2.     

Surface hardening in N<Superscript>+</Superscript> implanted polycarbonate

The influence of low energy nitrogen ions on the surface hardness of polycarbonate has been studied by implanting some of these specimens with 100 keV N⁺ ions at a beam current of 1 μA/cm² in the dose range of 1 × 10¹⁵ to 1 × 10¹⁷ ions cm^?2. Knoop microhardness has been found to be increased nearly 24 times at a load of 9.8 mN, for the dose of 1 × 10¹⁷ ions cm^?2. The structural changes occurred in implanted specimens were studied by Raman analysis, UV–Visible spectroscopy, and X-ray diffraction techniques. Raman studies point toward the formation of a structure resembling hydrogenated amorphous carbon. Disordering in the surface structure (I _D/I _G ratio) has also been found to increase with ion fluence using Raman technique. UV–Visible spectroscopic analysis shows a clear enhancement in Urbach energy (disorder parameter) from a value of 0.61 eV (virgin sample) to 1.72 eV (at a fluence of 1 × 10¹⁷ N⁺ cm^?2) with increasing ion dose. The increase in Urbach energy has been found to be correlated linearly with the increase in Knoop microhardness number. Results of X-ray diffraction analysis also indicate disordering in implanted layers as a result of implantation. In the present work, the possible mechanism behind the formation of harder surfaces due to implantation has been discussed in detail.     

Phase composition and magnetic properties of iron oxide nanoparticles obtained by impulse electric discharge in water

The chemical composition and the magnetic properties of iron oxide nanoparticles obtained by impulse electric discharge in water are investigated. The phase composition of the Fe₃O₄, Fe₂O₃, and Fe nanoparticles is determined. By means of the nuclear magnatiec resonance (NMR) technique, the magnetic moments of the nanoparticles are determined. The magnetic moment of the spherical nanoparticles equals to 2.39 × 10^–19 A m², and that of the cubical ones is 4.56 × 10^–19 A m².     

Experimental modeling of fast neutron-beam impact on Pt using Ar+ beams

Using the methods of field ion microscopy, we studied radiation-induced defects on an atomically clean surface and within a subsurface volume of platinum initiated by the interaction of neutron (E > 0.1 MeV) and Ar⁺ beams (E = 30 keV). It is shown that interaction of fast neutrons (E > 0.1 MeV, F = 6.7 × 10²¹ m^?2, and 3.5 × 10²² m^?2) with platinum leads to the same radiation damage in the volume of Pt as that produced by beams of Ar⁺ ions (E = 30 keV, F = 10¹⁶ ion/cm²) and is observed at a depth of about 1.5–2 nm beneath the irradiated Pt surface. Thus, we have carried out modeling of neutron impact with matter when replacing the neutron beam by an ion beam that causes the same radiation damage in the bulk of the material.     

Development of a water-in-oil-in-water multiple emulsion system integrating biomimetic aqueous-core lipid nanodroplets for protein entity stabilization. Part II: process and product characterization

The aqueous-core enclosed in lipid nanoballoons integrating multiple emulsions of the type water-in-oil-in-water mimic, at least in theory, the environment within viable cells, thus being suitable for housing hydrophilic protein entities such as bioactive proteins, peptides and bacteriophage particles. This study reports a complete physicochemical characterization of optimized biomimetic aqueous-core lipid nanoballoons housing hydrophilic (BSA) protein entities, evolved from a statistical 2³×3¹ factorial design study (three variables at two levels and one variable at three levels) that was the subject of the first paper of a series of three, aiming at complete stabilization of the three-dimensional structure of protein entities attempted via housing the said molecular entities within biomimetic aqueous-core lipid nanoballoons integrating a multiple (W/O/W) emulsion. The statistical factorial design followed led to the production of an optimum W/O/W multiple emulsion possessing quite homogeneous particles with an average hydrodynamic size of (186.2?±?2.6) nm and average Zeta potential of (?36.5?±?0.9) mV, and exhibiting a polydispersity index of 0.206?±?0.014. Additionally, the results obtained for the diffusion coefficient of the lipid nanoballoons integrating the optimized W/O/W multiple emulsion were comparable and of the same order of magnitude (10^?12 m² s^?1) as those published by other authors since, typically, diffusion coefficients for molecules range from 10^?10 to 10^?7 m² s^?1, but diffusion coefficients for nanoparticles are typically of the order of magnitude of 10^?12 m² s^?1.