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Gorgan, Iran

Javan M.B.,Golestan University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2015

We have used extended Huckel tight binding (EHTB) method considering Landauer-Buttiker formalism for investigating the electronic transport properties in linear nC20 (n ≤ 5) oligomers sandwiched between two Au (111) electrodes. We have presented the I-V and conductance characteristics of the nC;bsubesub& oligomers and also their dependences to the oligomer structural properties. It was found that the zero bias conductance of the energetically favorable nC;bsubesub& oligomers increases with growth of their length and the I-V characteristic remains almost linear at low bias voltages (up to 0.2 V). Some quantities such as transmission spectrum and electronic structure of nC;bsubesub& oligomers are discussed in the context. The results can be used for developing electronic nanodevices based on fullerenes. © 2014 Elsevier B.V. All rights reserved.

Dehno Khalaji A.,Golestan University
Journal of Cluster Science | Year: 2013

Nickel(II) complex, Ni(Brsalph)(NO3) was synthesized and characterized by elemental analyses and Fourier-transformed infrared (FT-IR) spectroscopy. Heating of Ni(Brsalph)(NO3) at 550 °C for 3. 5 h have resulted NiO nanoparticles. Fourier-transformed infrared spectrum confirmed the composition of products. The crystalline structures and morphology of NiO nanoparticles were studied by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. © 2012 Springer Science+Business Media New York.

This study focuses on the preparation and characterization of nickel oxide nanoparticles from nickel(II) Schiff base complexes as new precursors. At first nickel(II) complexes [Ni(salophen)] and [Ni(Me-salophen)] were synthesized and characterized by elemental analyses and FT-IR spectroscopy. Then NiO nanoparticles were prepared by solid-state thermal decomposition at 550 oC for 3. 5 h. The FT-IR spectrum confirmed the composition of products. The crystalline structures and morphology of products were studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results revealed that the obtained products were nickel oxide. SEM and TEM images demonstrated that the NiO nanoparticles have uniform shape with size between 35 and 70 nm. © 2012 Springer Science+Business Media New York.

Javan M.B.,Golestan University
Applied Physics A: Materials Science and Processing | Year: 2013

The structural, electronic and optical properties of SinC n (n = 12,16,20,30,35 and 60) nanocages were studied using different approximations of density functional theory, i.e. local density approximation (LDA), generalized gradient approximation (GGA) and density functional theory based tight binding approximation (DFTB). The highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) energy gaps were calculated for all nanocages. Time-dependent density functional theory (TD-DFT) was also applied for estimating of the optical excitation and exciton binding energies of the nanocages and the results compared with pure DFT calculations. © Springer-Verlag Berlin Heidelberg 2013.

Khabaz R.,Golestan University
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

A mathematical simulation approach based on the general purpose Monte Carlo N-particle transport code MCNP was developed to calculate the departure in reading of the neutron spectrometer instrument from that expected according to the inverse square law. The calculations were performed to evaluate the effects of beam divergence on the response of a 10 in. spherical device equipped with a long BF3 counter irradiated by 11 mono-energy neutron beams. The necessary geometry correction factor, because of non-uniform illumination, for the calibration of seven polyethylene spheres with several radionuclide neutron sources, i.e. Ra-Be, 241Am-Be, 241Am-B and Po-Be sources was also determined. In all calculations, the displacement of effective center from the geometric center of moderating spheres, when used as an instrument for neutron fluence measurement, was quantified. © 2013 Elsevier B.V.

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