Structural,dielectric and photoluminescence properties of co-precipitated Zn-doped SnO2 nanoparticles

Zn-doped SnO₂ nanoparticles were prepared by the chemical co-precipitation route. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses of these prepared nanoparticles were carried out for structural and morphological studies. All the samples have been found to have tetragonal rutile structure of the polycrystalline SnO₂ having crystallite size in the range 13–25 nm. TEM micrographs show agglomeration of nanoparticles in all the samples. At a particular temperature, the dielectric constant of all the samples has been found to decrease with increasing frequencies which may be due to rapid polarization processes occurring in SnO₂ nanoparticles. The ac conductivity, σ (ω), has been found to vary with frequency according to the relation σ (ω) ∝ ω^S. The value of S has been found to be temperature dependent, decreasing with increasing frequency which suggests that a hopping process is the most likely conduction mechanism in these nanoparticles. The room temperature photoluminescence (PL) spectra of the undoped and Zn-doped SnO₂ nanoparticles consist of the near band-edge ultraviolet (UV) emission and the defect related visible emissions. The origin of emission peaks in the visible region is attributed to oxygen-related defects that are introduced during growth.     

Brownian dynamics of rigid body by fluctuating hydrodynamic equations

In this work, Brownian dynamics of rigid body in an incompressible fluid with fluctuating hydrodynamic equations is presented. To demonstrate the Brownian motion of rigid body, fluctuating hydrodynamic equations have been coupled with equations of motion of rigid body. Thermal fluctuation is included in the fluid equations via random stress terms unlike the random terms in the conventional Brownian dynamics type approach. Calculation of random stress terms in the fluid is easier in comparison to the random terms in the particle motion. Direct numerical simulation for the Brownian motion of rigid body with a meshfree framework is analysed. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electronic structure calculations of substitutional and interstitial hydrogen in Nb

We report the results of a theoretical study on the effects of substitutional and interstitial hydrogen atoms in niobium. We confirm that any contaminated hydrogen will occupy the interstitial site over the substitutional site in niobium. For interstitial hydrogens, the lattice deformation increases with the percentage content of hydrogen, though it is negligible at low concentrations. Substitutional hydrogens are found to prefer off-center sites in the host lattice.     

A new numerical algorithm to solve fractional differential equations based on operational matrix of generalized hat functions

In this paper, we propose a new numerical algorithm for solving linear and non linear fractional differential equations based on our newly constructed integer order and fractional order generalized hat functions operational matrices of integration. The linear and nonlinear fractional order differential equations are transformed into a system of algebraic equations by these matrices and these algebraic equations are solved through known computational methods. Further some numerical examples are given to illustrate and establish the accuracy and reliability of the proposed algorithm. The results obtained, using the scheme presented here, are in full agreement with the analytical solutions and numerical results presented elsewhere.     

Tunable characteristics of one dimensional magnetic photonic crystal composed with single-negative materials

In this paper, we present the study of dispersion and transmittance characteristics of one dimensional magnetic photonic crystal composed by single negative indexed materials. For this structure, we have considered magnetic negative (MNG) with ? = 1 and μ < 0 and electric negative (ENG) with ? < 0 and μ = 4. We used simple transfer matrix method and Bloch's theorem for its analytical explanations. Analyzing transmittance characteristics of the proposed structure, we obtain the tunneling of certain frequency range where as the dispersion characteristic shows total forbidden for the same range for TM mode. The tunable property is found inside the band structure due to zero-?, zero-μ and magnetic behavior of the material. To identify zero-? and zero-μ of the structure, we have calculated the dispersion and the transmittance of the magnetic structure of MNG–ENG on different angles of incidence and thickness of layers.     

Polarized Infrared and Raman Spectra and Ab-initio Calculations of Benzotriazole

Abstract

The i. r. spectra of benzotriazole have been measured from 4000 to 60 cm^?1: polarized spectra of single crystals have been also obtained. The Raman spectra of polycrystalline samples and solutions have been investigated. The structural parameters and vibrational frequencies have been determined from ab-initio Hartree-Fock gradient calculations using the 6–31G* basis set. A detailed arsignment of most of the observed bands has been proposed on the basis of the i. r. dichroism, Raman polarization data and frequency calculations.

     

Vibrational Mean Amplitudes of XY3 Pyramidal Molecules

The vibrational mean amplitudes for bonded as well as for nonbonded distances have been evaluated for AsP₃, SbP₃, and PAs₃ at temperatures : T = 0^oK, T = 298.15^oK and T=500 ^oK using recent vibrational data. The results have been briefly discussed.     

Spectra of 2, 5- and 3, 4-Dichlorobromobenzene Molecules in Ultraviolet

Vibrational analyses have been presented for the absorption bands of 2, 5- and 3, 4-dichlorobromobenzene molecules photographed in the regions 2925 - 2690 A and 2900 - 2580 A respectively. The following constants have been determined:

The 0.0 band shifts have been explaine on the basis of simple additivity rule.     

Enhanced colorless and broadcast capable symmetrical 10-Gbps bidirectional transmission in WDM-PON using RSOA and EAM

Here we proposed a novel architecture of wavelength division multiplexed-passive optical network (WDM-PON) in which the downlink unicast data, broadcast data and uplink unicast data transmission is possible with the symmetric data rate of 10 Gbps. At remote node (RN) cyclic wavelength routing property of array waveguide grating (AWG) and power splitting capacity of power splitter is used in the architecture so that broadcast channel can be overlaid on downlink unicast channels. At ONU carriers sent from central office (CO) is reused for upstream data transmission with the help of integration of a reflective semiconductor amplifier (RSOA) and an electro-absorption modulator (EAM) so there is no need of extra laser sources at ONUs which makes them colorless. EAM can be operated at very high speed; a modulation bandwidth of tens of GHz can be achieved. Broadcast channel causes a limited interference with downlink and uplink unicast channels so it does not affect the system performance. Since each channel has different wavelength so NRZ data is used which eliminates expensive DPSK receivers and detection becomes very easy. Simulation is performed with all channels having data rate of 10 Gbps having acceptable performance.     

Performance of ferrite fillers on electrical behavior of polymer nanocomposite electrolyte

Dispersal of nanofillers in polymer electrolytes have shown to improve the ionic properties of Polyethylene oxide (PEO)-based polymer electrolytes in recent times. The effects of different nanoferrite fillers (i.e., Al–Zn ferrite, Mg–Zn ferrite, and Zn ferrite) on the electrical transport properties have been studied here on the composite polymer electrolyte system. The interaction of salt/filler with electrolyte has been investigated by XRD studies. SEM image and infrared spectral studies give an indication of nanocomposite formation. In conductivity studies, all electrolyte systems are seen to follow universal power law. Composition dependence (with ferrite filler) gives the maximum conductivity in [93PEO–7NH₄SCN]: X ferrite (where X?=?2% in Al–Zn ferrite, 1% Mg–Zn ferrite, and 1% Zn ferrite) system.