Journal of Nano Research Vol. 24

Abstract: The aim of this study was to investigate the morphology and optical absorption of PbI₂ thin films. PbI₂ films of different thickness were deposited on glass substrate at ambient temperature by thermal evaporation technique. The deposition rate was optimized at 1-2 nm/s to grow uniform good quality films. The structural analysis of the films was carried out by X-ray diffraction (XRD). The morphology of so prepared films was studied by Scanning Electron Microscope (SEM). The absorption spectra were recorded using a UV-Vis fiber optics based spectrophotometer. All the measurements in the present work were carried out at room temperature (~300 K). PbI₂ seems to have a very strong affinity for the growth of preferred (001) orientation. The d spacing of (00l) peaks match quite well with ASTM data for 2H polytype of PbI₂ which confirms the stoichiometry. A uniform spherical grain size growth is clearly evident from SEM micrographs. Optical absorption analysis indicates that the Lead Iodide is having a direct optical band gap of about 2.45 eV. The variation of band gap with film thickness could be qualitatively understood as due to the quantum confinement effect.

Abstract: Oil and Gas industry is going through a phase where there is an increased demand of energy sources (particularly oil and gas) and reduced production due to mature oilfields. There is a need for new technologies which can help improve production from the reservoir and develop new fields. Nanotechnology offers promising solution for the same. Nanotechnology is the study of science of materials at nanoscale which help in enhancing the performance of processes. Nanoparticles are the nanosized materials in the range of 1-100 nm. Nanoparticles have high specific surface area and unique properties, such as high adsorption potential and heat conductivity. These particles when mixed with base fluids, also called as nanofluids, and used for several application related to upstream oil and gas industry, help improve the performance of several processes. The use of nanoparticle in exploration and production is an attractive tool for petroleum engineers that have been improved by many researchers in recent years. This paper discusses about how the nanotechnology plays an important role in an upstream oil and gas industry which includes exploration, drilling, and completion, production and enhanced oil recovery operation.

Abstract: Nanocrystals are important to attain high performance in optical & magnetic materials such as phosphors, laser emitters and information recording media. They are also required in future devices that involve magnetoresistance, logic gates, magnetic resonance and metamaterials. Nanocrystals of oxides and nitrides (and oxynitrides) were studied as nanosized powders, nanowires and dispersed granular thin films. Recent advancements of such nanocrystals prepared at Hokkaido University are introduced in this paper. Nanocrystals were prepared in transparent conducting oxides, white LED phosphor oxides and oxynitrides and magnetic iron nitride. Nanowires were grown in semiconducting gallium oxynitride and magnetic nanogranular thin films were prepared both in oxide and nitride.

Abstract: In the present research work, an anatase structure titanium dioxide nanoparticle was synthesized by hydrolysis of titanium isopropoxide in the presence and absence of ultrasonication. The resultant product suspension was peptized for getting narrow size distribution. The synthesized nanoparticles are used for preparation of nanofluids with different volume percent loading of nanoparticles in water ranging from 1% to 5%. The characterization of particles was carried out by TEM, XRD. Our result shows that the use of ultrasonic technique has a significant effect on the homogeneity and then size of TiO₂ nanoparticles. Viscosity of nanofluids was demonstrated with rheometer (TA instruments). Viscosity results confirmed Newtonian behavior of nanofluids and showing increasing trends with addition of nanoparticles in base fluids. The dispersion of nanoparticles in nanofluids is studied with unique method of UV visible spectrophotometer, which confirm good dispersion stability prepared nanofluid of 50 hrs.

Abstract: Fiber-reinforced polymer composites have played a dominant role for a longtime in a variety of applications for their high specific strength and modulus. The fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural. Past studies show that only synthetic fibers such as glass, carbon etc., have been used in fiber-reinforced plastics. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. An attempt has been made to utilize the coir, as natural fiber abundantly available in India. Natural fibers are not only strong and lightweight but also relatively very cheap. The present work describes the development and characterization of a new set of natural fiber based polyester composites consisting of coir as reinforcement and epoxy resin. Coir composites are developed and their mechanical properties are evaluated, at five different volume fractions and tests were carried out and the results were presented. Experimental results showed tensile, static and Dynamic properties of the composites are greatly influenced by increasing the percentage of reinforcement, and indicate coir can be used as potential reinforcing material for many structural and non-structural applications.

Abstract: A simple method is developed for the synthesis of carbon nanotubes (CNTs) using Mo-Co/MgO catalyst by a thermal chemical vapor deposition (CVD) technique. Acetylene was used as the source of carbon and nitrogen as carrier gas. A series of MgO supported Mo-Co catalysts were prepared by the combustion route using urea as the fuel at different stoichiometric ratios. It was found that a higher yield of carbon nanotubes was obtained by the developed catalysts. Also, the addition of molybdenum to Co/MgO catalysts could remarkably increase the yield and also improve the quality of CNTs from thermal CVD with acetylene as precursor gas. The morphology of the catalysts and CNTs obtained was studied by field emission scanning electron microscope (FE-SEM). Other techniques like Raman spectroscopy and XRD were also employed to know the physico-chemical properties of the samples.

Abstract: Two different E-glass fiber reinforced plastic (GFRP) composite laminates having quasi isotropic [(+45/-45/0/90)₂]_S layup sequence were fabricated viz., GFRP with neat epoxy matrix (GFRP-neat) and GFRP with modified epoxy matrix (GFRP-nano) containing 9 wt. % of CTBN rubber micro-particles and 10 wt.% of silica nanoparticles. Standard fatigue test specimens were machined from the laminates and end-tabbed. Spectrum fatigue tests under a standard fighter aircraft load spectrum, mini-FALSTAFF, were conducted on both the composites at various reference stress levels and the experimental fatigue life expressed as number of blocks to fail, were determined. The stiffness of the specimen was determined from the load-displacement data acquired at regular intervals during the fatigue test. The matrix cracks development in the test specimens with fatigue cycling was determined through optical photographic images. The fatigue life of GFRP-nanocomposite under mini-FALSTAFF load sequence was observed to be enhanced by about four times when compared to that of GFRP-neat composite due to presence of micro-and nanoparticles in the matrix. The stiffness degradation rate and matrix crack density was considerably lower in GFRP-nanocomposite when compared to that of GFRP-neat composite. The underlying mechanisms for improved fatigue performance of GFRP-nanocomposite are discussed.

Abstract: We report here the highly stable niosomes (non-ionic vesicles) from 1:1 Tween-80/Triton X-100 mixed surfactants in presence of n-octanol as an organic additive. Niosomes of nanometer dimensions resulted at a total surfactant concentration ranging from 0.1 1 wt%. The critical concentration of the additive, n-octanol used to form niosomes was found to be 15 mM. The unilamellar vesicles thus formed had a mean diameter of ~100 nm for 0.1 wt% and ~300 nm for 1 wt% concentration. Phase evolution in the mixed 1:1 Tween-80/Triton X-100 surfactant system was unraveled upon investigating the morphology, based on microscopic and dynamic light scattering investigations. The formed vesicles are envisaged as probable potential drug carriers.

Abstract: A detail investigation on the stability and electronic properties for a series of bimetallic (semiconductor-alkaline earth) clusters, viz., Si_xMg₃ (x=1-10) is performed in search for the exceptional or unusual stable motifs. A standard generalized gradient approximation (GGA) exchange-correlation functional, as proposed by Perdew, Burke and Ernzerhof (PBE) is employed for this purpose under the density functional formalism. The magic stability of the concerned clusters is explained using the jellium and aromaticity models. It is evident from the present study that the magic stability of Si₇Mg₃ cluster arises due to the jellium shell closure whereas the same for Si₄Mg₃ originates from the σ dominated aromaticity over its π counterpart.