Journal of Nano Structures
Volume:2 Issue: 3, Summer 2012

Mesoporous MgO microstructures were synthesized using magnesium acetate tetrahydrate, ammonium oxalate monohydrate and Pluronic F127 via heating at 40 °C for 24 h and subsequent calcination. The mesoporous structure of magnesium oxide with the specific surface area of 47m2/g, pore volume 0.30 cm3/g and the average pore size 24 nm is produced. According to XRD studies, the diffraction peaks of the product pattern can be indexed to the cubic structure magnesium oxide with the lattice parameter of a = 4.22 Å and showing no impurities. The product was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction analysis, N2 adsorption-desorption and Scanning electron microscopy.

Co-Fe films were electrodeposited on Cu substrate from electrolytes with different Co concentration levels. X-ray diffraction (XRD) was used to investigate the films crystal structures. The results indicate that if the Co concentration is less that the Fe concentration, the cubic structure appears in the films, while the hexagonal structure dominates when the Co concentration is sufficiently more than the Fe concentration. The films composition was studied using energy dispersive X-ray spectroscopy (EDX). The EDX results indicate that increasing of the electrolyte Co concentration leads to an increase in the Co content in the Co-Fe alloy films but in a non-linear manor. Morphological observations by scanning electron microscopy (SEM) indicated that the Co-Fe grain size increases when the electrolyte Co concentration is increased. Magnetic measurements by vibration sample magnetometer (VSM) show that the films have in-plane magnetization easy axes. Furthermore, the saturation magnetization increases as the Co concentration increases.

Electrospinning was applied to nitrocellulose (NC) solutions in DMF, DMSO and Ethyl methyl keton to obtain NC nanofibers. Electrospraying process was observed when DMF was used as solvent. In comparison to NC/DMF, NC/DMSO solution resulted in the formation of a coating film as indicate by SEM. Two different electrospun nanofibers, smooth nanofibers with 90 to 150 nm diameters and porous nanofibers with 400 to 500 nm diameter, was noticed when EMK was used. Electrospun explosive composite nanofibers were also successfully prepared from NC to modify the properties of NC and their morphology were investigated by SEM. Explosive materials such as nitrotriazolone (NTO), its sodium salt, picric acid and nanosilver were used as the second component of the composites. A reduction in the diameters of the composite nanofibers involving Na- NTO was noticed comparing to the parent NC nanofibers. The diameters of the other explosive composite nanofibers were in the range of 50-300 nm indicating no significant diameter change for NC nanofibers upon the addition of 0.1 wt% NTO and picric acid. Composite nanofibers containing nanosilver particles were also prepared and their antibacterial activities were tasted against E. coli and S. aureus. These nanofibers successfully inhibited the growth of both bacteria.

ZnO plays an important role in many semiconductors technological aspects. Here, direct precipitation method was employed for the synthesis of nano-sized hexagonal ZnO particles, which is based on chemical reactions between raw materials used in the experiment. ZnO nanoparticles were synthesized by calcinations of the ZnO precursor precipitates at 250 ˚C for 3hours. The particle size and structure of the products have been confirmed by XRD. The FT-IR study confirms the presence of functional groups. Also, the morphology and size distribution of ZnO nanoparticles was analyzed by TEM images. The optical properties were investigated by UV–Visible spectroscopy. The XRD results show that the size of the prepared nanoparticles is in the range of 20–40 nm, which this value is in good agreement with the TEM results. The FT-IR spectrum clearly indicates the formation of an interfacial chemical bond between Zn and O. Also the UV absorption depends on the particles size and morphology, so the optical properties enhances with decreasing nanoparticles size. Moreover the direct precipitation technique is a feasible method for production of ZnO nanopowders.

A numerical study has been done through an Al2O3–water in a double lid-driven square cavity with various inclination angles and discrete heat sources. The top and right moving walls are at low temperature. Half of the left and bottom walls are insulated and the temperatures of the other half are kept at high. A large number of simulations for a wide range of Richardson number of 0.1 to 10, Reynolds number from 1 to 100, inclination angle of cavity from -90o to 90o and solid volume fraction between 0 and 0.06 are performed. The results are presented in the form of streamline, isotherm and Nusselt number plots. The influence of solid volume fraction of nanofluids and angle of inclination on hydrodynamic and thermal characteristics have been analyzed and discussed. As a result, it was found that the heat transfer increases with increase in solid volume fraction for a constant Reynolds number, heat transfer also increases with increase in Richardson and Reynolds for a particular volume fraction.

Polyvinylpyrrolidone / Nickel oxide (PVP/NiO) dielectrics were fabricated with sol-gel method using 0.2 g of PVP at different working temperatures of 80, 150 and 200 ºC. Structural properties and surface morphology of the hybrid films were investigated by XRay diffraction (XRD) and Scanning Electron Microscope (SEM) respectively. Energy dispersive X-ray spectroscopy (EDX) was used to make a quantitative chemical analysis of an unknown material. The obtained results demonstrate the feasibility of using high dielectric constant nanocomposite PVP/NiO as gate dielectric insulator in the organic thin film transistors (OTFTs).

The corrosion protection abilities of modified copper in 2-[((Z)-1-{6- [(2-sulfanylphenyl)ethanimidoyl]-2-pyridyl}ethylidene) amino]-1- benzenthiol solution containing TiO2 nanoparticles were evaluated by Tafel polarization and impedance spectroscopy in 3.5% sodium chloride solution. The samples were characterized by energy dispersive X-ray (EDX) and scanning electron microscopy (SEM). The electrochemical results indicated corrosion resistance of this coating depends on the concentration of TiO2 nanoparticles and assembling time at this solution. After immersing copper for 10 min in Schiff base solution containing 150 mg L-1 nanoparticles, the coating was able to protect the copper against corrosion about 97%. Results indicated high ability of coating at high temperature and immersing time in sodium chloride solution.

A chemically modified carbon paste electrode with multiwall carbon nanotube (MWCNT) was prepared and used as a sensor for Cu2+ ion. The unique chemical and physical properties of CNT have paved the way to new and improved sensing devices. A central composite chemometrics design was applied for multivariate optimization of the effects of three significant parameters (Graphite powder (X1), MWCNT (X2) and Ionophre (X3)) influencing the response of the electrode. In the optimized conditions, the electrode exhibits a Nernstian slope of 30.1 mV/decade in a linear range between 1.0×10-6 to1.0×10-1 M over a wide pH range (2.0-6.5). Importantly, the effect of the MWCNT on the performance of electrode was investigated by impedance technique, that showed the MWCNT helps the transduction of the signal in carbon paste electrode and the charged transfer resistance (Rct) was reduced. The impedimetric results indicated that the linear concentrations range was 1.0×10−7 to 1.0×10−1 M and in comparison with potentiometry, the pH range increased to 2.0−7.5.

Using principle of minimum total potential energy approach in conjunction with Rayleigh-Ritz method, the electro-thermomechanical axial buckling behavior of piezoelectric polymeric cylindrical shell reinforced with double-walled boron-nitride nanotube (DWBNNT) is investigated. Coupling between electrical and mechanical fields are considered according to a representative volume element (RVE)-based micromechanical model. This study indicates how buckling resistance of composite cylindrical shell may vary by applying thermal and electrical loads. Also, applying the reverse voltage or decreasing the temperature, increases the critical axial buckling load. This work showed that the piezoelectric BNNT enhances on the whole the buckling resistance of the composite cylindrical shell.

Diopside has been successfully prepared by a modified sol-gel method.Optimization in calcination temperature and mechanical ball milling resulted in a pure and nano-sized powder which characterized by means of scanning electron microscopy (SEM), Xray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared Spectroscopy (FT–IR). We hypothesized that nano-sized diopside would mimic more efficiently the nanocrystal structure and function of natural bone apatite, owing to the higher surface area, compare to conventional micron-size diopside. Accordingly, we used the unique advantage of nanotechnology to improve novel nanodiopside particles as a potential candidate for bone tissue regeneration whether as a periimplant filling powder or in combination with other biomaterials as a composite scaffold.

CuInS2 nanostructures were synthesized via a simple surfactant-free solvothermal route. In this synthesis, thiosemicarbazide and thioglycolic acid were used as sulfur sources. The effects of different parameters such as type of precursor and time on the morphology and particle size of the samples have been investigated. The nanostructures were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive Xray analysis (EDX), Fourier transform infrared (FT-IR) and photoluminescence (PL) spectroscopy. The fill factor (FF), open circuit voltage (Voc), and short circuit current (Isc) were obtained by I–V characterization.

CuAlS2 Chalcopyrite nanocrystalline are synthesized with facile method. The heat arrested solvothermal method for synthesize nanocrystalline were investigated. The time duration of synthesis, temperature of solution and metal salts to solvent molar ratio can be parameters that we are studied. The nanoparticles were synthesized with CuCl, AlCl3 and thiourea (SC(NH2)2) as precursors, Diehylene glycol ((CH2CH2OH)2O) and Polyethylene glycol 600 (HO(C2H4O)nH) as solvent and capping agent respectively, and Ammonia (NH4OH) as reducing agent. The parameters of synthesis were studied by X-Ray diffraction (XRD) for analysis of structure and by ultraviolet–visible (UV-VIS) spectrophotometer for analysis of light structure. The possible formation mechanism metal complexes, sulfur ions and chalcopyrite compound are also discussed.

This article provides an overview on preparation, design, crystal structure and properties of some metal-organic frameworks of carboxylate coordination polymers mixed with pyridine-functionality linkers prepared in our laboratory. The article covers coordination polymers in two- and three-dimensional supramolecular architectures. The reported coordination polymers exhibit interesting structural features for cobalt and nickel centers. They also show various physical properties together with high thermal stabilities, which candidate them for a wide range of applications. Moreover, one of the frameworks was used as a precursor for preparation of metal oxide nanoparticles with sizes of about 35-45 nm.