Effect on Optical and Antibacterial Activity of SnO2 and CuO Blended SnO2 Nanoparticles

Nanocrystalline SnO2 and CuO doped with SnO2 were prepared by the co-precipitation method and characterized for different physiochemical properties and microbiological activity. The composition and morphological formation were characterized by XRD, HRTEM, Raman, FTIR, and UV-vis spectroscopy. The Powder X-ray analysis reveals that Sn4+ ions have substituted the Cu2+ ions without changing the monoclinic structure of SnO2 but the average particle size of the SnO2 and CuO doped SnO2 samples from 11 and 5 nm respectively. However, it exhibits an inhibiting strong bacterial growth against tested bacterial strains.

Simulation Study of Nanoscale FDSOI MOSFET Characteristics

Silicon on insulator (SOI) technology permits a good solution to the miniaturization as the MOSFET size scales down. This paper is about to compare the electrical performance of nanoscale FD-SOI MOSFET at various gate lengths. The performance is compared and contrasted with the help of threshold voltage, subthreshold slope, on-state current and leakage current. Interestingly, by decreasing the gate length, the leakage current and on-state current are increased but the threshold voltage is decreased and the sub-threshold slope is degraded. Silvaco two-dimensional simulations are used to analyze the performance of the proposed structures.

Synthesis and Characterization of Polypyrrole (PPy) Thin Films

Polypyrrole (PPy) was synthesized by chemical oxidative polymerization technique using monomer pyrrole and ammo-nium persulphate as an oxidant in a ratio of 1:1. Thin films of polypyrrole were prepared by dissolving polypyrrole in mcresol and cast using spin coating technique on glass substrates. Thin films of polypyrrole were characterized by X ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infra red spectroscopy (FTIR), UV visible spectroscopy and electrical resistivity by four probe method. The XRD spectra showed that the polypyrrole is amorphous in nature. SEM studies revealed a uniform granular structure of PPy. The FTIR spectra shows that the presence of all characteristics absorption peaks of polypyrrole that is, 890 cm?1 (=C–H out-of-plane vibration), 1040 cm?1 (=C–H in-plane vibration), 1170 cm?1 (N–C stretch bending) and 1410 cm?1 (pyrrole ring vibration). UV visible study shows PPy films exhibit absorption peak at 446 nm (2.77 eV). Room temperature electrical resistivity of PPy is in the critical regime of the metal –to –insulator (M-I) transition.

Preparation of PVDF/SiO₂Composite Nanofiber Membrane Using Electrospinning for Polymer Electrolyte Analysis

Superhydrophobic poly(vinylidene fluoride) PVDF-SiO2 composite membranes with different % of SiO2 contents were prepared by electrospinning. The surface morphologies of the membranes are characterized by using scanning electron microscopy. The nanofibers in the membranes were stacked in layers to produce fully interconnected pores that resulted in high porosity. The incorporation of SiO2 into the nanofiber membrane improved the ionic conductivity from 0.2428 × 10-4Scm-1 to 7.731 × 10-4Scm-1 at room temperature. The surface roughness of the membranes increased with increasing the SiO2 content, while the average diameter of nanofibers was rarely affected. Superhydrophobic PVDF membrane with a contact angle larger than 136° was prepared by the electrospinning of the SiO2 functionalized PVDF. The surface composition of the membranes is analyzed by using FTIR and the contact angles and water drops on the surface of the membrane are measured. The contact angle experimental results of PVDF-SiO2 composite membranes showed an improvement of hydrophobicity with % of nano SiO2.

Phase Transition Behavior of Nanocrystalline Al₂O₃Powders

Alumina (Al2O3) has been synthesized through combustion synthesis (CS) technique. The calcined products were characterized using X-ray diffractional analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo-gravimetric analysis (TGA). TG-DTA results reveal the various stages involved in transition from γ-phase to α-Al2O3 phase. The first phase γ-Al2O3 was presented in the temperature range from 600°C-875°C as deduced from the XRD patterns with cubic crystal structure. The second stage occurs in the temperature range from 900°C-1000°C. In the final step, above 1000°C, the aluminium oxide appears completely as α-Al2O3, showing high crystallinity. The particle sizes are closely related to γ- to α-Al2O3 phase transition.

Effect of Substrate on CuS/PVA Nanocomposite Thin Films Deposited on Glass and Silicon Substrate

Transition metal chalcogenide nanocomposite thin films deposited by chemical routes are currently attracting wide attention being inexpensive, simple and have utility for large area applications. The role of substrate becomes very important in film deposition as well as in controlling their properties due to strain induced properties modification and lattice mismatch. CuS/PVA nanocomposite thin films were successfully deposited on glass and silicon substrates using sol-gel technique. Thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-visible (UV-VIS) and Raman spectroscopy. Structural data confirm the amorphous nature of as grown films which transform into crystalline films after annealing at 200°C. The degree of crystallinity seems to be better in film deposited on silicon substrate in comparison to those grown over glass substrate with average crystallite sizes ≅?4.00 nm and 7.00 nm for films deposited on glass and silicon substrate respectively. Atomic force microscopy (AFM) images in dynamic as well as contact modes display nanoparticles embedded in polymer network. The films surface roughness parameters quantitatively estimated from AFM micrographs are compared. Raman spectra show a sharp peak at ≅474 cm¯1 assigned to S-S stretching mode of S2 ions in films grown on both substrates and associated as due to presence of hexagonal (covellite) crystal structure. Optical band gaps of thin film on glass and silicon substrate are 2.10 eV and 2.02 eV respectively. The effect of substrate on the measured properties is discussed.

One-Step Preparation and Characterization of Zinc Phosphate Nanocrystals with Modified Surface

The surface-modified zinc phosphate (Zn3(PO4)2) nanocrystals were synthesized by a facile and efficient one-step ultrasonic-template-microwave (UTM) assisted route. The crystal structure, optical properties and morphologies of zinc phosphate nanocrystals were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and transmission electron microscope. And the TEM image showed that the product had good dispersion with a particle size of 30 – 35 nm. The anti-corrosion function of anti-corrosive paint using zinc phosphate nanocrystals was researched and the experiment result showed that the salt atmosphere–resistant time was 158 h longer than that of zinc phosphate bulk materials on market. The performance of zinc phosphate nanocrystals with modified surface synthesized by one-step UTM assisted route was improved 63.2% compared with the bulk materials.

Synthesis and Characterization of Monodisperse Magnetite Hollow Microspheres

Monodisperse hollow magnetite microspheres were successfully synthesized by an one-step process through a tem-plate-free hydrothermal approach employing simultaneously a mixture of FeCl3.6H2O and ferrocene as precursor and a propylene glycol-isopropanol mixture as solvent. The morphologies and properties of the magnetite microspheres were characterized by X-ray diffraction (XRD), Raman and infrared spectroscopy, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), adsorption of nitrogen (BET method) and SQUID magnetometry. The results show that the microspheres consist of a single crystalline phase of magnetite. On the other hand, the size and the internal hollow of the microspheres depend on the temperature of growth and can be tuned by modifying the synthesis conditions.

Effect of Laser Fluence on the Characteristics of Ag Nanoparticles Produced by Laser Ablation

6-12 nm silver nanoparticles were synthesized by the pulsed laser ablation of a high purity silver bulk in distilled water. Effect of laser fluence on the size, morphology and structure of produced nanoparticles has been studied experimentally. Pulses of a Q-switched Nd:YAG laser of 1064 wavelength at 7 ns pulse width at different fluences were employed to irradiate the silver target in water. The UV-Visible absorption spectra of the Ag nanoparticles exhibit surface plasmon resonance absorption peak in the UV region. TEM and SEM micrographs, in a good agreement with DLS results, indicate that with increasing the laser fluence the average size of spherical Ag nanoparticles is decreased. It is found that Ag nanoparticles exhibit photoluminescence emission with two peaks because of the inter band transition and electron-hole recombination.

Dependence of Laser Ablation Produced Gold Nanoparticles Characteristics on the Fluence of Laser Pulse

Effect of laser fluence on the characteristics of gold nanoparticles (NPs) produced by laser ablation method is investigated experimentally. Five samples of gold NPs were synthesized by nanosecond pulsed laser ablation of a high purity gold plate in distilled water at five different fluences in the range of 1-3 J/cm2. Results show that in this experimental condition gold NPs are produced by nucleation of Au atoms in the plasma, generated on the target surface during the ablation process. There is threshold fluence at which absorption of laser energy by water rises significantly. Absorption of the laser energy by water leads to increase oxygen atoms in the ablation medium and formation of gold oxide NPs. By increasing the laser fluence below the threshold, size of produced NPs decreases while by increasing the laser fluence above the threshold size of produced NPs increases.

Preparation and Characterization of Subsurface Silver Particulate Films on Polymer Blends of Polystyrene/Poly(2-vinylpyridine)/Poly(vinylpyrollidone)/Poly(4-vinylpyridine)

Silver particulate thin films on softened polymer blends of Polystyrene (PS)/Poly(2-vinyl pyridine) (P2VP), PS/Poly(4-vinylpyridine) (P4VP), and Poly(vinylpyrollidone) (PVP)/P4VP at a rate of 0.4 nm/s held at a temperature of 457 K in vacuum of 8 × 10-6 Torr by evaporation are deposited. These silver films were characterized by their electrical behavior, optical properties and Scanning electron microscopy (SEM). Silver films deposited on softened PS, and PVP give rise to a very high room temperature resistance approaching that of the substrate resistance due to the formation of a highly agglomerated structure. On the other hand, silver films on softened P2VP and P4VP give rise to a room temperature resistance in the range of tens to a few hundred MΩ/ which is desirable for device applications. Silver films on the composites of PS/P2VP, PS/P4VP and PVP/P4VP show resistances at room temperature. The optical and plasmonic response of Ag nanoparticles onto thin layers of blends shows encapsulation of nanoparticles. The electrical properties and SEM of silver nanoparticles on the thin layers of polymer blends indicate the formation of much smaller, narrower dispersion and wide size distribution.

Enhanced Electrochemical Capacitance of Nitrogen-Doped Carbon Nanotubes Synthesized from Amine Flames

This paper presents a new process for synthesizing a kind of nitrogen- doped carbon nanotubes (N-CNTs) with primarily a ‘graphite-like’ structure at N substitutions from flames using n-propylamine and n-butylamine as fuels. When the N-CNTs are used as the supercapacitor electrode materials, they exhibit a much larger capacitance than the regular carbon nanotubes (CNTs). It is proposed that the high proportional ‘graphite-like’ N dopant in the as-grown N-CNTs improves their surface chemical activity and conductivity and then results in a desirable performance for electro-chemical capacitors.

Structure and Mechanical Behavior of Cellulose Nanofiber and Micro-Fibrils by Molecular Dynamics Simulation

Cellulose nanofiber (CNF) and CNF micro-fibrils (CNF-MFs) are computationally modeled by molecular dynamics with united atom (UA) methodology of polymers. Structural stability and mechanical properties of these materials are focused on. Diffusion coefficient decreases with increase of the number of shells in CNF-MF. The structure of CNF-MFs with crystalline alignment is totally stabilized with twist which is an accumulation of torsion angles at Glycosidic bonds between monomers inside CNFs. Unique fiber drawing simulation, where a single CNF fiber is taken out of CNF-MF structure, is first conducted. The CNF fiber which is drawn out stretches up to relatively large strain, with linear increase of tensile stress. The computation results show that, the larger the number of shell structure of CNF-MF is, the larger the stretch and the stress of drawn fibers are.

Polymeric Liquid Templating of Hierarchical Porous Films by Nanofibrillar Alginic Acid Assemblies

Hierarchical phases of the biomaterials can be used as template to transfer their intricate organization into biomimic inorganic solids. Herein, hierarchical mesoporous silica films with aligned pores have been templated by nanofibrillar alginic acid. An aqueous suspension of the alginic acid nanofibers was prepared by treating the brown seaweeds with sodium carbonate solution and subsequent precipitation in dilute hydrochloric acid. The alginic acid nanofibers of the organize into a hierarchical aligned phase in an acetic acid-sodium acetate buffer that was used to template silica-alginic acid composite films by evaporation induced self-assembly of alkoxysilane with nanofibrillar alginic acid. Calcination of the alginic acid template afforded hierarchical mesoporous silica glasses. Carbonization of the silica-alginic acid composites and subsequent etching the silica recovered mesoporous carbon supercapacitors.

Universal 2D Soft Nano-Scale Mosaic Structure Theory for Polymers and Colloids

A basic concept in chain-particle cluster-motion, from frozen glassy state to melt state, is the 2D soft nano-scale mosaic structure formed by 8 orders of 2D interface excitation (IE) loop-flows, from small to large in inverse cascade and rearrangement structure in cascade along local one direction. IE has additional repulsive energy and extra vacancy volume. IE results from that the instantaneous synchronal polarized electron charge coupling pair is able to parallel transport on the interface between two neighboring chain-particles with antiparallel delocalization. This structure accords with de Gennes’ mosaic structure picture, from which we can directly deduce glass transition temperature, melt temperature, free volume fraction, critical entangled chain length, and activation energy to break solid lattice. This is also the inherency maximum order-potential structure in random systems.

Controlled Synthesis and Characterization of Nobel Metal Nanoparticles

In this work, monodispersed, well-shaped platinum (3.2 - 6.4 nm), rhodium (2.4 - 5.1 nm), palladium (3.2 - 5.3 nm) nanoparticles capped with poly(vinylpyrrolidone) were synthesized by a polyol reduction method in an ethylene glycol solution at temperature of 190℃. The influences of synthetic parameters on the size and morphology of the noble metal nanoparticles have been systematically investigated. The noble metal nanoparticles were characterized by means of UV-vis, laser scattering particle size distribution analysis (LSPSDA) and transmission electron microscopy (TEM). The experimental results showed that the particle size of metals nanoparticles, the morphology of which was spherical, increased with the raise of metal precursor concentration as well as the amount of PVP. The optimal molar ratio of PVP/metal and metal precursor concentration for the fabrication of Pt, Rh, and Pd nanoparticles with uniform distribution were 10 and 0.1 mM, respectively. The morphologies of the Rh nanoparticles with the size of 5.1 nm were polygons, including hexagons, pentagons, and triangles.

Optical and Electrical Properties of Nanocrystalline SnO₂Thin Films Synthesized by Chemical Bath Deposition Method

The chemical bath deposition (CBD) technique was used for the synthesis of the tin oxide (SnO2) thin films. X-ray diffraction (XRD) was employed to find the crystallite size by using Debye Scherrer’s formula. The surface morphology of SnO2 films was analyzed by the scanning electron microscopic (SEM) studies. The FT-IR spectrum exhibits the strong presence of SnO2. The optical properties of the SnO2 thin films were determined using UV-Visible spectrum. The dielectric studies were carried out at different frequencies and at different temperatures for the prepared SnO2 thin films. Further, electronic properties, such as valence electron plasma energy, average energy gap or Penn gap, Fermi energy and electronic polarizability of the SnO2 thin films, were determined. The ac conductivity of the SnO2 thin films increases with increase in temperature and frequency. The activation energy was determined by using dc electrical conductivity measurement. The Hall properties were also calculated.

Photon Correlation Spectroscopy and SAXS Study of Cylindrical to Spherical Transition in the AOT Microemulsion by Changing Solvent

We study dynamic and structure of nano-droplets of AOT/water/oil microemulsion with different oils at water/AOT molar ratio of 6.7. Photon correlation spectroscopy is used to study collective diffusion coefficient of nano-droplets at AOT microemulsion with decane and cyclohexane. The collective diffusion coefficient of nanodroples is increasing with change of oil from decane to cyclohexane. The structure of AOT microemulsion with decane and cyclohexane is founded with SAXS. Our results show, nano-droplets of AOT microemulsion with decane at X = 6.7 have cylindrical structure and AOT microemulsion with cyclohexane at X = 6.7 have spherical structure.

Determination and Analysis of Structural and Optical Properties for Thermally Evaporated ZnO Thin Films

ZnO films have been deposited on glass slide substrates at room temperature by thermal evaporation technique. The prepared samples were annealed at temperature of 300°C and 400°C in air atmosphere. Optical and structural properties of as-deposited films have been compared by that of the annealed samples. X-ray diffraction (XRD) patterns of the obtained films showed that they have polycrystalline and exhibit wurtzite structure. Micro-structural properties such as mean crystallite size and micro-strain were discussed from XRD peak broadening. Optical properties were identified by measuring transmittance using UV-Vis spectrophotometer. The optical constants such as the refractive index n, extinction coefficient k as well as films’ thickness were calculated in the spectral range of 350-800 nm from transmittance data using a reverse engineering method (point-wise unconstrained minimization approach, PUMA). Dispersion of refractive index shows similar trend as Cauchy relation. Absorption coefficient depicts a maximal value around 3.33 eV for annealed samples. Using balance between electrical power and emissive power, the temperature of tungsten furnace was calculated under deposition condition. The connection between temperature and vapor pressure of ZnO was estimated by the Clausius-Clapyeron equation and thermochemical data.

A Single-Step Process for Preparing Supercapacitor Electrodes from Carbon Nanotubes

This paper introduces an easy single-step process for preparing the supercapacitor electrode from carbon nanotubes (CNTs) which were directly grown on a nickel foam framework by a chemical vapor deposition (CVD) technique. Due to the hierarchical porous structure and robust CNT-metal contacts, the present electrode exhibits better capacitive performance and lower internal resistance than the regular transfer method. Its specific capacitance of 25 F/g is 127 % higher than the value of the electrode prepared by the transfer method. This work proposes a simple, effective and eco-nomical approach for preparing a supercapacitor electrode without additional catalysts and pre- or post-treatments.