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Full-Text Articles in Physics

Phonon Transmission Via Nanojunctions In Bcc Waveguides, Ouahiba Nafa, Boualem Bourahla, Rachid Tigrine Jan 2010

Phonon Transmission Via Nanojunctions In Bcc Waveguides, Ouahiba Nafa, Boualem Bourahla, Rachid Tigrine

Turkish Journal of Physics

Coherent and ballistic phonon transport via nanojunctions between bcc lattices is presented. The model system A/B/A consists of a finite number of bcc atomic layers of an element B sandwiched between two bcc semi-infinite crystals of another element A. The matching method theoretical approach is used to study the dynamical properties of the bcc sandwich system. A calculation is presented for the coherent reflection and transmission scattering probabilities of the system phonons, as elements of a Landauer type scattering matrix. The scattering and transmission spectra via the nanojunctions are analyzed as a function of the incident frequency per propagating mode …


Computations Of Ultrasonic Parameters Of Lanthanide Metals Ti, Zr And Hf, Pramod Kumar Yadawa, Dharmendra Kumar Pandey, Devraj Singh, Raja Ram Yadav, Giridhar Mishra Jan 2010

Computations Of Ultrasonic Parameters Of Lanthanide Metals Ti, Zr And Hf, Pramod Kumar Yadawa, Dharmendra Kumar Pandey, Devraj Singh, Raja Ram Yadav, Giridhar Mishra

Turkish Journal of Physics

The ultrasonic properties in the hexagonal structured lanthanide metals Ti, Zr and Hf have been studied at room temperature. The higher order elastic constants have been calculated for these metals using Lennard-Jones Potential for evaluating orientation-dependent ultrasonic properties. An anomalous behaviour in orientation dependent velocity is obtained, which is due to the combined effect of second order elastic constants and density. The achieved ultrasonic properties are compared with known physical parameters to differentiate them from third group nitrides/laves phase compounds.


The Investigation Of Hardness And Bonding Behavior In Xb_4, X = {Ce, Th, U, Pa}, Tetraborides By First-Principles, Sezgi̇n Aydin, Aynur Tatar Jan 2010

The Investigation Of Hardness And Bonding Behavior In Xb_4, X = {Ce, Th, U, Pa}, Tetraborides By First-Principles, Sezgi̇n Aydin, Aynur Tatar

Turkish Journal of Physics

The mechanical and electronic properties of XB_4, X = {Ce, Th, U, Pa}, tetraborides have been studied by using first-principles based on density functional theory. The results show that these boron-rich solids are mechanically and thermodynamically stable. From the calculated band structure and density of states, we obtained that they have metallic character. When the calculated parameters related to the crystal structure were considered with the bonding characteristics, the microscopic hardnesses of these boron-rich solids can be theoretically calculated. The obtained hardness values indicate that, these materials are hard, but not superhard. Furthermore, from the detailed hardness analysis, we found …


Sublimation Of Graphite In Continuous And Pulsed Arc Discharges, Afshan Ashraf, Kashif Yaqub, Sumera Javeed, Sumaira Zeeshan, Rahila Khalid, Sohail Ahmad Janjua, Shoaib Ahmad Jan 2010

Sublimation Of Graphite In Continuous And Pulsed Arc Discharges, Afshan Ashraf, Kashif Yaqub, Sumera Javeed, Sumaira Zeeshan, Rahila Khalid, Sohail Ahmad Janjua, Shoaib Ahmad

Turkish Journal of Physics

Sublimation of graphite has been investigated in continuous and pulsed arc discharges. The results of continuous arc discharge between graphite electrodes are compared with pulsed arc discharge between cylindrical Aluminum cathode and annular graphite anode. The sublimed species include monoatomic and diatomic carbon clusters with their relative composition depending upon the mechanism of energy dissipation in graphite electrodes. Diatomic carbon (C_2) is the dominant subliming cluster. Emission spectroscopy of the Swan band system [d^3\prod _g -a^3\prod _u ] of C_2 has been used to investigate the thermodynamic state and to deduce the vibrational temperature (T_{vib}). The vibrational level densities indicate …


Effect Of Substrate Temperature On The Optical Properties Of Thermally Evaporated Zns Thin Films, M. Ruhul Amin Bhuiyan, M. Monjarul Alam, M. Abdul Momin Jan 2010

Effect Of Substrate Temperature On The Optical Properties Of Thermally Evaporated Zns Thin Films, M. Ruhul Amin Bhuiyan, M. Monjarul Alam, M. Abdul Momin

Turkish Journal of Physics

Zinc Sulfide (ZnS) thin films were formed onto cleaned glass substrates using the thermal evaporation method in vacuum. The substrate temperature was varied between as- deposited and 150 °C, keeping the film thickness and the rate of evaporation fixed at 200~nm and 0.3~nm \cdot s^{-1}, respectively. The film thickness was measured in situ by a quartz crystal thickness monitor. The structure of the films was ascertained by x-ray diffraction (XRD) method. The XRD spectra show that the films are polycrystalline in nature, which possess hexagonal structure. The optical properties of the films were ascertained by UV-VIS-NIR spectrophotometer (photon wavelength ranging …


Chemical Bath Deposition And Characterization Of Cu_2o-Cu_Xs Thin Films, D. D. O. Eya Jan 2010

Chemical Bath Deposition And Characterization Of Cu_2o-Cu_Xs Thin Films, D. D. O. Eya

Turkish Journal of Physics

Cu_2O-Cu_xS thin films have been deposited on glass substrate by chemical bath deposition technique. The films were obtained by depositing Copper Sulphide (Cu_xS) on Copper (I) Oxide (Cu_2O) and then Cu_2O on Cu_xS. The peak solar transmittance across the thin films were found to be


Electron Paramagnetic Resonance Study Of Vo^{2+} Doped Single Crystal Of Ferroelectric Guanidinium Uranyl Sulphate Trihydrate, Mohammad Imtiazul Haque, Mohammad Umar Jan 2010

Electron Paramagnetic Resonance Study Of Vo^{2+} Doped Single Crystal Of Ferroelectric Guanidinium Uranyl Sulphate Trihydrate, Mohammad Imtiazul Haque, Mohammad Umar

Turkish Journal of Physics

We report result obtained from an EPR study of vanadyl ion (VO^{2+}) in a single crystal of ferroelectric guanidinium uranyl sulphate trihydrate. The Spin-Hamiltonian parameters were also determined via EPR data. VO^{2+} enters the lattice interstitially at two distinguishable sites and resulting vanadyl complexes have nearly axial symmetry.


A Case Study On \Sigma \Lambda Conversion In P-Shell Hypernuclei, Masroor Bukhari Jan 2010

A Case Study On \Sigma \Lambda Conversion In P-Shell Hypernuclei, Masroor Bukhari

Turkish Journal of Physics

The important process of \Sigma-\Lambda conversion is presented and discussed in this report and a case example has been presented reviewing some cross sections and decay widths calculated for the process in a p-shell hypernucleus in recent studies.


Exact Solutions For The Double Sinh-Gordon And Generalized Form Of The Double Sinh-Gordon Equations By Using (G'/G)-Expansion Method, Hossein Kheiri, Azizeh Jabbari Jan 2010

Exact Solutions For The Double Sinh-Gordon And Generalized Form Of The Double Sinh-Gordon Equations By Using (G'/G)-Expansion Method, Hossein Kheiri, Azizeh Jabbari

Turkish Journal of Physics

In this paper, the (G'/G)-expansion method is applied to seek traveling wave solutions to the double sinh-Gordon and the generalized form of the double sinh-Gordon equations. With the aid of a symbolic computation system, two types of more general traveling wave solutions (including hyperbolic functions and trigonometric functions) with free parameters are constructed. Solutions concerning solitary and periodic waves are also given by setting the two arbitrary parameters, involved in the traveling waves, as special values.


Influence Of The Nitrogen Concentration On The Electrical Characteristic Of Hydrogenated Amorphous Silicon Nitride (A-Sin_X:H) Based Schottky Diodes, İlker Ay, Hüseyi̇n Tolunay Jan 2010

Influence Of The Nitrogen Concentration On The Electrical Characteristic Of Hydrogenated Amorphous Silicon Nitride (A-Sin_X:H) Based Schottky Diodes, İlker Ay, Hüseyi̇n Tolunay

Turkish Journal of Physics

In this study, the Schottky diode characteristic of hydrogenated amorphous silicon nitride (a-SiN_x:H) samples containing various amounts of nitrogen have been investigated via both I-V and C-V measurements. From forward bias I-V measurements in the dark, the barrier height of samples (\phi_{B0}), ideality factor (\eta ), modified Richardson constant (A^\ast) and series resistances (R_s) have been obtained as the function of temperature for different nitrogen content. In addition, forward and reverse bias current ratios (I_f/I_r) at V~=~1 volt have been investigated as the function of temperature for different nitrogen content. Light sensitivity of the samples has also been investigated under …


Photocurrent And Surface Recombination Mechanisms In The In_Xga_{1-X}N\Slashgan Different-Sized Quantum Dot Solar Cells, Hossein Movla, Foozieh Sohrabi, Jafar Fathi, Hassan Babaei, Arash Nikniazi, Khadije Khalili, Nima Es'haghi Gorji Jan 2010

Photocurrent And Surface Recombination Mechanisms In The In_Xga_{1-X}N\Slashgan Different-Sized Quantum Dot Solar Cells, Hossein Movla, Foozieh Sohrabi, Jafar Fathi, Hassan Babaei, Arash Nikniazi, Khadije Khalili, Nima Es'haghi Gorji

Turkish Journal of Physics

We present a p-i-n structured solar cell with stacked layers of In_xGa_{1-x}N Quantum Dots (QDs) with different indium composition. The photocurrent and surface recombination processes are investigated in the i-region. We have shown that the QDs in the i-region can play the role of both generation or recombination centers. The photocurrent has been calculated by self-consistent method to solve continuity equation of charge carriers in the layers of the i-region. By changing the Indium composition in In_xGa_{1-x}N QDs, the band gap of QDs varies and therefore provides a considerable overlapping with solar spectrum. Proposed SC with different-sized QDs and different …


Structure And Optical Properties Of Cuals_2 Thin Films Prepared Via Chemical Bath Deposition, Tariq Alwan, Mushtak Jabbar Jan 2010

Structure And Optical Properties Of Cuals_2 Thin Films Prepared Via Chemical Bath Deposition, Tariq Alwan, Mushtak Jabbar

Turkish Journal of Physics

CuAlS_2 thin films of thicknesses 118 \pm 5 nm were deposited on glass substrates using chemical bath deposition technique. The details of the preparation method are well described. The method is relatively simple and is easily controlled and sufficient to produce large area and good adherence to the substrate films. Effect of annealing temperature T_a on the structure, and optical properties of CuAlS_2 films were investigated. The structures of the films were studied by X-ray diffraction and FTIR spectrophotometer. The optical properties of the films were ascertained by UV-VIS spectrophotometer (wavelengths ranging between 300 and 900 nm). The optical transmittance …


Effects Of Deformation Ratio On The Mechanical Properties And Microstructures Changes In An Al-Mg-Si Alloy, Hichem Farh, Rebai Guemini, Serradj Fares, Karim Djemmal Jan 2010

Effects Of Deformation Ratio On The Mechanical Properties And Microstructures Changes In An Al-Mg-Si Alloy, Hichem Farh, Rebai Guemini, Serradj Fares, Karim Djemmal

Turkish Journal of Physics

An investigation has been done to study the effect of deformation ratio and two-step ageing treatment on the microstructure and the mechanical properties in an Al-Mg-Si aluminum alloy. Transmission electron microscopy is used in order to follow the distribution and the morphology of the hardening precipitates. The hardness of the alloy increases with the increasing deformation ratio. The maximum of hardness increases and is shifted to low time with an increase of the deformation ratio. The density of precipitates is more increased and the precipitates become more inhomogeneously distributed when the deformation combines with two-step ageing treatments.


Vibration Spectra Of Polar Mixing Optical Phonon States And Fröhlich Electron-Phonon Coupling Behaviors In A Wurtzite Zno Quantum Dot, Li Zhang Jan 2010

Vibration Spectra Of Polar Mixing Optical Phonon States And Fröhlich Electron-Phonon Coupling Behaviors In A Wurtzite Zno Quantum Dot, Li Zhang

Turkish Journal of Physics

Based on the dielectric continuum model and Loudon's uniaxial crystal model, the interface-optical-propagating (IO-PR) mixing phonon states of a quasi-zero-dimensional (Q0D) wurtzite cylindrical quantum dot (QD) are investigated. It is found that there are two types of IO-PR mixing phonon modes, i.e. \rho-IO/z-PR mixing modes and the z-IO/\rho-PR mixing modes coexisting in Q0D wurtzite QDs. Numerical calculation on a wurtzite ZnO QD shows that the dispersion frequencies of the mixing modes are discrete functions of the azimuthal quantum number and axial wave-number. The calculated results agree well with the recent experimental spectra in ZnO QDs. An abnormal electron-phonon coupling strength …


Inept Nmr Spectroscopy Of ^{14}Nd_N Groups: Product Operator Theory And Simulation, Deni̇z Türkpençe, İrfan Şaka, Azmi̇ Gençten Jan 2010

Inept Nmr Spectroscopy Of ^{14}Nd_N Groups: Product Operator Theory And Simulation, Deni̇z Türkpençe, İrfan Şaka, Azmi̇ Gençten

Turkish Journal of Physics

Product operator formalism is widely used for the analytical description of multi-dimensional and multiple-pulse NMR experiments for the weakly coupled spin systems having spin-1/2 and spin-1 nuclei. The INEPT NMR experiment is a polarization transfer experiment including J-coupling. In this study, the INEPT NMR experiment was analytically investigated by using product operator theory for weakly coupled IS_n(^{14}ND_n) (I=1, S=1; n=1, 2, 3) spin systems. The obtained theoretical results represent the FID values of ^{14}ND_n groups. In order to make Fourier transform of the obtained FID values, a Maple program is used and then simulated spectra of the INEPT experiment are …


On The S-Wave Jost Solution For Coulomb-Distorted Nuclear Potential, Ujjwal Laha, Bibekananda Kundu Jan 2010

On The S-Wave Jost Solution For Coulomb-Distorted Nuclear Potential, Ujjwal Laha, Bibekananda Kundu

Turkish Journal of Physics

A closed form expression of the off-shell Jost solution for Coulomb plus separable nuclear potential is derived using interacting Green's functions and their integral transforms. As an application of our result the off-shell Jost function for the proton-proton scattering in the ^1S_0 channel is computed for various laboratory energies to investigate the role of long range Coulomb interaction in off-shell scattering.


Role Of Quadrupole Deformation In Proton Emitting Nuclei In The Medium Mass Region, Chandrasekaran Anu Radha, Velayudham Ramasubramanian, Emmanuel James Jebaseelan Samuel Jan 2010

Role Of Quadrupole Deformation In Proton Emitting Nuclei In The Medium Mass Region, Chandrasekaran Anu Radha, Velayudham Ramasubramanian, Emmanuel James Jebaseelan Samuel

Turkish Journal of Physics

Nuclear structural studies at and beyond the proton drip line is done with the help of proton radioactivity. It is found that nuclei are not necessarily always spherical. The aim of the present work is to study the role of quadrupole deformation in proton rich nuclei, particularly with respect to odd Z nuclei within the region 50 < Z < 80 near the proton drip line. The deformation is studied using triaxially deformed cranked Nilsson Strutinsky method with tuning. Some of the nuclei in the medium mass region are found to be proton emitters from the ground state with appreciable deformation. Nuclei with 62 < Z < 67 shows considerable deformation that kindled the probability of instability within the nuclei. Significant ground state deformed shapes are observed in the 67 < Z < 73 region.


On Robertson-Walker Universe Model With Variable Cosmological Term And Gravitational Constant In Cosmological Relativity Theory, Kangujam Priyokumar Singh Jan 2010

On Robertson-Walker Universe Model With Variable Cosmological Term And Gravitational Constant In Cosmological Relativity Theory, Kangujam Priyokumar Singh

Turkish Journal of Physics

This paper presents cosmological models in which the gravitational and cosmological constants G and \Lambda are time-dependent. We find a variety of solutions for the variation of cosmological parameters. It is also found that, in the case of matter dominated Robertson-Walker Universe, if the cosmological constant \Lambda \ne 0, the Hubble's constant H is not constant at all but inversely proportional to the cosmic time. The conservation law for the energy momentum tensor is still valid with our law of variation: \Lambda \propto R^{-2} and G\rho \propto \frac{\Lambda }{8\pi}.


Convective Inertia Effects On The Squeeze Film Between Rectangular Parallel Plates, Sikiru Adigun Sanni Jan 2010

Convective Inertia Effects On The Squeeze Film Between Rectangular Parallel Plates, Sikiru Adigun Sanni

Turkish Journal of Physics

This paper investigates the effects of convective inertia on the lubricating characteristics of the squeeze film between parallel rectangular plates. Relaxing a simplifying assumption of the conventional lubrication theory, the paper retains some terms of the convective inertia terms of the Navier-Stokes equations, leading to a derivation of a modified Reynolds equation. The introduction of the convective inertia terms induces two inversely related dimensionless parameters, m and R (the Reynolds number), into the characteristics of the flow behavior. The dimensionless normal (or squeezing) velocity increases monotonically from the lower plate to the upper plate for given value of R. At …