JOURNAL OF RESEARCH ON MANY BODY SYSTEMS
Year:2017 | Volume:6 | Issue:12|Papers Count:8

In this investigation, the manganese ferrite nanoparticles MnFe2-xCrxO4) x=0, 0.25, 0.5, 0.75) were prepared. Structural properties of samples were analyzed using X- ray diffraction and field emission scanning electron microscopy (FESEM). By evaluating XRD results, using Scherrer’s equation, the size of the crystallites was obtained about 4 nm. FESEM images indicated agglomerated nanoparticles for samples. The magnetic properties have been characterized by using AC susceptometer and vibrating sample magnetometer (VSM). Given the results of VSM, the study found that the magnetization of nanoparticles decreased with increasing Cr doping. AC magnetic susceptibility of samples shows, the response of samples is dependent on the applied frequency. Results showed that the prepared samples at low temperatures indicate super spin–glass behavior with strong interaction between nanoparticles.

A nonrelativistic model was used to determine the energy shift of low lying states of meson charmonium with respect to the Cornell, Martin, logarithm and global potentials. It is shown that at the lowest order of perturbation, the ground state acquires an energy shift that is proportional to the inverse square of the noncommutative length scale. We estimated an upper bound on noncommutative scale of order 0.397_ 3.021GeV, by using the recent most accurate experimental data on ortho and paracharmonium meson spectra.

In the dye sensitized solar cell, the dye molecules play the role of light absorption that is a key role in performance of the solar cells. One of the features that affect the optical spectrum of dyes is size of the nano molecules. In this paper, the optical spectrum of nano molecules of coumarin families was calculated with different sizes by using the Time-Dependent Density-Functional Tight-Binding and Time-Dependent Density-Functional methods. In this calculation, the HOMO-LUMO gap increases as the size of the dyes decreases in accordance with the experiment. Our computations confirm the 2 order of speed of first method compared to the second method. Finally, Time-Dependent Density-Functional Tight-Binding method proposed the S-cis Nkx-2311 with ZnO for the simulation of the dye sensitized solar cell.

In the present work, the calculation of differential and total cross sections is done for the formation of the positronium atom in low-energy in the collision of positron with the hydrogen atom. In these calculations, the hydrogen atom was considered in the ground state and the probability of forming the positronium atom by three-body problems was examined by method close-Coupling. In the first channel, the wave function was extended by orthogonal basis Laguerre. The discussed region of energy is 10-100 eV and the scattering angles are selected to be from 0 to 180 degree. The obtained results and the total cross section results were compared with different available experimental and theories data. The cross section is the maximum around the energy 20eV and shows the possibility of positronium formation in this energy higher than the other.

The present paper applies an optoacoustic method for generation of the first and second sound waves in superfluid helium4. Two wave equations related to pressure and temperature vibrations in time unit are concluded using linear hydrodynamic equations and conducting numeral calculations, and two thermal and electrostriction mechanism are observed. Analyses incurred in this paper are related to crystal parts of superfluid helium. Absorption coefficient of these crystal parts is nearly zero, and the only dominant mechanism is electrostriction one. Two sound waves are studied including first sound wave that is propagation of pressure vibrations and second sound wave that is propagation of temperature vibration in superfluid helium4. We shine laser light in the form of a continuous wave on superfluid helium4 after generating wave equations, and observe generation normal first and second sound waves and fast and slow sound waves in superfluid helium4.We Also observed that reducing of the laser beam radius amplitude (w), increases the pressure and temperature vibrations amplitude in superfluid helium4.

This paper is an attempt to investigate the structural properties, phase transition, and thermodynamic and phonon properties of AlAs. Quasi-harmonic Debye- Einstein model was used to obtain lattice constant and static Bulk modulus B0 for B3, B8 and B1phases. These results showed good consistency with experimental results and other theoretical data. Afterwards, the phase transitions of B3 to B1 and B3 to B8 obtained were equal to 7.9 GPa and 11.2 GPa respectively, which also indicated a good consistency with the theoretical and experimental results. In addition, phonon properties of B3 phase were compared with experimental data, and the results demonstrated a good consistency with experimental results especially in the gamma point that is the basis of thermodynamic calculations. Furthermore, the diagrams of heat capacity at constant volume and heat capacity at constant pressure were investigated in terms of temperature for B3 phase, and the results showed their significant consistency with theoretical and experimental results.

Colliding high energy cosmic rays to the earth atmosphere produces secondary particles which generate extensive air shower (EAS) that develops in lateral and longitudinal directions. It was found that electron density in two directions is related to the age parameter. Dai et. al. [1] clarified the difference between the lateral and longitudinal age parameters in 1990. However, some scientists believe that the lateral age parameter from NKG model is not sufficient to describe the electro lateral dispersion. In the current study, given the experimental and simulation data and also given the results of Dai et. al. work, the dependence of the lateral and longitudinal age parameter to core distance is investigated. Finally, contrary to NKG theory, at Linsley theory, the age parameter is not a constant parameter, so it increases with an increase in core distance.

Cadmium telluride nanopowders were synthesized through the hydrothermal method at different temperatures and reaction times. The prepared samples were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance UV-vis spectroscopy (DR UV-vis). The XRD patterns revealed that the secondary phases almost disappeared in the sample synthesized at 180oC for 80h. SEM images showed that the average particle size of the prepared CdTe powders is about 85 nm. Investigation of optical properties confirmed that CdTe nanopowders synthesized by hydrothermal are ideal materials to be used as the absorber layer in fabricating optical devices such as solar cells.