This study seeks to obtain data about electric and optical properties of ZnSe/SiO2 composite films for Photovoltaic Applications, for this purpose ZnSe nanoparticles established in [Si O2] thin films were prepared by sol-gel method using zinc acetate dihydrate [Zn (CH3 COO)2 .2H2O], selenic acid [H2SeO4] and Tetraethyl orthosilicate [Si(OC2H5)4]. The n – ZnSe /SiO2 thin film composites were deposited on the glass substrate by dip coating technique. Mobility activation has been studied from the photocurrent degradation curves. XRD results indicate the phase structure of ZnSe particles embedded in ZnSe/SiO2 composite thin films is sphalerite (cubic ZnS). The effective density of states (Neff), frequency factor (S), and trap depth (E) have been calculated for all the films having different crystallite sizes. The increase in photoconductivity is explained in terms of built in potential barriers (φb) at the crystallite boundaries. Field Emission Scanning Electron Microscopy (FESEM) image show that morphology of n - ZnSe influenced by ZnSe/SiO2 molar ratio. The optical characterization of thin film composite has been examined by transmittance measurement in the UV-visible wavelength range. It was found that the optical transmission is decreased with increase of the ZnSe/SiO2 molar ratio. The highest transmission of 54.6% and the lowest of 36.7% were acquired for the specimens with 5% and 20% ZnSe/SiO2 molar ratio, respectively. Further observation shows that the optical transition in ZnSe/SiO2 thin film is direct transition with band gap energy in the range of 2.6 - 3.9 eV.
In this paper, a ferroelectric structure consisting of barium stannate titanate piezoelectric ceramic is used for mathematical modeling. The study of the dynamics of the structure requires the poling process that makes the ceramic active. This may be explained by the time-dependent nonlinear polarization behavior. The model results in a nonlinear second order ordinary differential equation of one degree of freedom. Analytical exact solutions have been obtained for three regimes following the specific value of the damping parameter. Numerical simulations of these solutions by optimization with Matlab package showed excellent agreement in comparison with measurements and a mean square error of order of 10-5 is obtained.
By applying the exact Stirling formula and the exact function , the occupation number of particles was calculated based on the statistics of Boltzmann distribution for a finite number of particles n. The exact analytical expression of occupation number of particles (ni) is found in terms of the Lambert W function and is more general than that usually calculated by the standard Boltzmann distribution based on the Stirling approximation. The new expression in the exact and algebraic closed form eliminates the need for the complex iterative computation. Its high accuracy is proved by a comparison of calculating occupation number of particles (ni) with respective numerical solution.
Palm kernel shell and coconut shell have been combined in equal proportion to produce activated carbons for supercapacitor electrode and water filter. Microwave-assisted activation technique was employed for the production at a much shorter time (ranging from 5-10 min) and reduced cost compared to the conventional activation methods. Co-activator (mixture of NaCl and CaCl2) was used to activate the sample for water filter with no added fillers while the sample for supercapacitor electrode was activated with KOH and NiO nanoparticles as fillers. Physical properties (such as density, ash content and moisture content) and Thermo-Gravimetric Analysis (TGA) were carried out to ascertain the quality of the activated carbons. In addition to the microstructural and structural investigations, surface functionalities, adsorption capability and electrochemical properties of the samples were also investigated. The surface chemistry, microstructure, structure and electrochemical properties of the produced activation carbon were investigated employing Fourier Transform Infra-Red (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS).The effectiveness of the activated carbon sample for water filter was tested for the removal of organic dye (methylene blue) from water contaminated with the organic dye via adsorption studies using the Freundlich model. Finally, the results; obtained from electrochemical studies, show that the activated carbon for supercapacitor electrode possesses good current response with high value of specific capacitance and it is a promising component for electrochemical devices.
This review describes some nano-technological applications concerning the corrosion incidence and protection of steel pipelines mainly used in the petroleum sector. These techniques play a major role in producing anti-corrosion coatings which enhances metal durability with high abrasion and corrosion resistances towards adverse environmental conditions. In addition the review also describes the advantages for employing nano-materials in protecting metal and other material surfaces.
