JOURNAL OF RESEARCH ON MANY BODY SYSTEMS
Year:2016 | Volume:6 | Issue:11|Papers Count:6

In this study, using a self-consistent model and considering the random phase approximation, we have calculated the screening function of semiconducting zinc oxide (ZnO) and indium arsenide (InAS) nanowires coated by dielectric environment. We show that when these nanowires are coated by high dielectric media (larger than nanowire dielectric) the dielectric function of free charge is reduced inside the nanostructure. However, in a low dielectric media (lower than semiconductor dielectric) the dielectric function is increased. Moreover, the behavior of dielectric function versus the variation of radius, carrier density of nanowire and dielectric media is investigated in liquid helium temperature and in the temperature range of 4-300 K.

Ince-Gaussian beams are a complete member of Helmholtz-Gauss beams and are exact and orthogonal solution of paraxial wave equation in elliptical cylindrical coordinates. In this paper, numerical evaluation of the M2 factor of Ince-Gaussan beams based on second order moments of intensity is presented. The results show that the M2 factor is an increasing function of mode order whereas it is independent of mode number. These calculations can help optical system designers to compute the quality factor of these beams very easily without the need to use other complex calculations.

ZnS nanolayers were deposited on clean glass substrates at different temperatures, by either physical vapor deposition (PVD) or spray pyrolysis (SP) method. All the samples were annealed in air at 5000 C. Optical and structural properties of the thin films were examined by UV/v is spectroscopy and XRD analysis. Band gaps of the ZnS thin films are obtained from the spectroscopy data. XRD analysis shows that all the films have a cubic structure. By annealing, crystallinity of the samples is improved and the grain sizes are increased. Transparencies of the samples become lower as the films thickness is increased. However, the PVD samples are higher and the SP ones lower transparent through the annealing process. Different behaviors of the samples to the annealing process and film thickness are also discussed.

In the present paper, the first-order electron and nuclear amplitudes are calculated in the framework of three-body formalism within corrected boundary conditions in the first order Born approximation and active electron model. Both the differential and total scattering cross sections, for the formation of positronium in collision of positron with methane molecule, are obtained using the differential amplitudes in the non-relativistic intermediate and high impact energies and are compared with the available experimental data. The selected impact energy and positron scattering angle fall in the ranges between 400 eV and 2 keV and 0 and to 180 degree, respectively. The cross section is computed in the center of mass frame and converted to the laboratory frame.

In this paper, W-type hexaferrites nanostructure with SrNi2Fe16O27 composition with molar ratio of acid citric 1, 1.5 and 2 were prepared by sol-gel auto combustion method. First, the gel of samples was ignited at 300 oC and powders were annealed at 900, 1000 and 1100oC temperatures. Nanostructures of papered were characterized by X-ray diffraction pattern devices (XRD), Field emission scanning electron microscope (FESEM), Fourier transform infrared spectrophotometer (FT-IR) and vibrating sample magnetometer (VSM). The X-ray diffraction pattern of samples show that in mole ratio of 1 pure phase was formed at 1000 oC and by increasing the molar ratio the temperature for formed SrNi2Fe16O27 phase increased. The results of field emission scanning electron microscope showed that in different molar ratios, various morphology is obtained and by increasing the molar ratio of citric acid, the size of the particles increases. The peaks of FT-IR absorption samples in rang of 430-590 cm-1 and 550-590 cm-1 is corresponding to tetrahedral and octahedral sites in the ferrites. Hysteresis curve of the samples showed that by increasing the molar ratio of citric acid, the specific saturation magnetization increasing and also the coercivity decreases.

The Born effective charges, zone center phonon modes and infrared reflectivity spectra at normal incidence on the [100] and [001] surface of BaWO4 were calculated, using density functional perturbation theory. The calculated born effective charges display large deviations from nominal ionic charges, reflecting the mixed ionic-covalent nature of the chemical bonding. The phonon modes were identified in terms of symmetry species, using group theory and character table of C4h point group. The calculated phonon frequencies were in good agreement with the reported experimental values. The obtained results predict the frequency of a Raman active Bg mode that has not been earlier observed experimentally.