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Articles 1351 - 1380 of 1382
Full-Text Articles in Physical Sciences and Mathematics
The Structure Of (001) Csl Twist Boundaries In Fcc Metals, A. Ghafoor, S.A. Ahmad, B.A.S. Faridi
The Structure Of (001) Csl Twist Boundaries In Fcc Metals, A. Ghafoor, S.A. Ahmad, B.A.S. Faridi
Turkish Journal of Physics
Computer simulation techniques based on discrete lattice approach and empirical many-body potentials have been used to study the structure and energy of $\Sigma = 5$, and $\Sigma = 13$ coincident site lattice (001) twist boundaries in three fcc metals. Energy computed for $\Sigma = 5$ boundary in copper is 17.5 \% less than the earlier result obtained by using pair potential. However the present calculations of twist boundary energies are somewhat higher than the results obtained using embedded atom method.
The Energy Spectra Of Gaas/Al_Xga_{1-X}As Quantum Dots, Mohammad El-Said, M. Abu Saa
The Energy Spectra Of Gaas/Al_Xga_{1-X}As Quantum Dots, Mohammad El-Said, M. Abu Saa
Turkish Journal of Physics
The energy expressions for QD presented in high- and low-magnetic fields are calculated. An interpolation formula between the energies of the quantum dot in both limits is proposed. The formula is implemented to produce the energy spectra of the parabolic quantum dot in the presence of a magnetic field of arbitrary strength. The transitions in the angular momenta of the ground state energy of interacting electrons confined in the quantum dot as a function of magnetic field strength is studied. A good agreement is obtained when our results are tested against exact numerical work.
Thermodynamics And Structure Of Simple Liquid Metals Calculated Using An Analytic Pair Potential, Serap Dalgiç, Seyfettin Dalgiç, M. Tomak
Thermodynamics And Structure Of Simple Liquid Metals Calculated Using An Analytic Pair Potential, Serap Dalgiç, Seyfettin Dalgiç, M. Tomak
Turkish Journal of Physics
The analytic interatomic pair potential for simple metals is derived from first principles using second order pseudopotential theory by Pettifor and Ward . It is developed using the Heine-Abarenkov pseudopotential for simple metals and applied to the calculations of the structural and thermodynamic properties of liquid metals. The corresponding liquid metal structure is calculated using the random phase approximation and the hypernetted-chain formulation. The long-wavelength limit S(0) of the structure factor of liquid metals using the hard-sphere system as reference is also investigated. The calculated thermodynamic and structural properties using the real space formalism are in better agreement with experimental …
Multiple Scales Method For A Matrix Kdv Equation, Mehmet Naci Özer
Multiple Scales Method For A Matrix Kdv Equation, Mehmet Naci Özer
Turkish Journal of Physics
In this paper the method of multiple scales is used to derive an integrable matrix non-linear Schrödinger equation (MNLS) as an amplitude equation from the Matrix Korteweg-de Vries equation (MKdV) associated with symmetric spaces. Then the integrability of the MNLS equation is deduced by the derivation of the spectral problem for the MNLS equation from the spectral problem for the MKdV equation.
Space Charge Limited Current In Films Obtained In Glow Discharge Plasma, M.M. Akhmedov, M.K. Kerimov, B.A. Suleimanov, S.A. Mansimov
Space Charge Limited Current In Films Obtained In Glow Discharge Plasma, M.M. Akhmedov, M.K. Kerimov, B.A. Suleimanov, S.A. Mansimov
Turkish Journal of Physics
The electrical current in thin films obtained by the polymerization of acetonitrile in glow discharge on a heated substrate were investigated in order to determine the mechanism of electrical conduction. The results of the field dependence, sample thickness dependence of the dark conductivity, supported by the results of photocurrent measurements, suggest an exponential energy distribution of traps inside the band gap of the polymer.
Eect Of Sintering Time On Sb Added Bipbsrcacuo Superconducting Ceramics, K. Kocabaş
Eect Of Sintering Time On Sb Added Bipbsrcacuo Superconducting Ceramics, K. Kocabaş
Turkish Journal of Physics
In this study, superconducting Sb doped BiPbSrCaCuO ceramics with a fixed nominal composition were prepared and sintered at 850^oC for different periods. The structural phases of the sintered ceramics were determined by means of the measurements of the resistivity-temperature behaviour and of the XRD analysis. Sb doping along with Pb doping in the BiSrCaCuO ceramics was observed to increase the volume fraction of the high $T_c$ phase, the onset temperature and the critical temperature $T_c$. The critical temperature for the 100 hour sintered sample was 4K higher than that of the 60 hour sintered sample.
The Effect Of Temperature Dependent Frequency Factor On The Evaluated Trapping Parameters Of Tsl Glow Curves, A. N. Yazici, Z. Öztürk
The Effect Of Temperature Dependent Frequency Factor On The Evaluated Trapping Parameters Of Tsl Glow Curves, A. N. Yazici, Z. Öztürk
Turkish Journal of Physics
The effect of temperature dependency on frequency factor and its relationship to trapping parameters is discussed by using the peak shape method. The coefficients appearing in the peak shape formula for the calculation of the activation energy have been determined and tabulated for the symmetry factor $\mu_g(X)$ for $x=0.50$ and 0.75 of the peak intensity. It is found that significant errors occur in the value of the trapping parameters if the temperature dependecy of the frequency factor is not consider.
A Time-Dependent Quantum Study Of Li+Hf(\Nu=1) -> Lif(\Nu')+H, Fahrettin Gögtaş, Gabriel G. Balint-Kurti
A Time-Dependent Quantum Study Of Li+Hf(\Nu=1) -> Lif(\Nu')+H, Fahrettin Gögtaş, Gabriel G. Balint-Kurti
Turkish Journal of Physics
Time-dependent quantum wave packet calculations are performed for a model based (two-dimensional) $Li+HF(\nu=1)\ra LiF(\nu^{\prime})+H$ reaction. The reaction probabilities for a broad range of collison energies are calculated by a single solution of the time-dependent Schr\\"{o}dinger equation. The calculated reaction probabilities show many sharp features as a function of energy which are ascribed to scattering resonances.
Fine Structure Analysis Of 4702 ^Oa Band Of The Molecule, M.B. Sureshkumar, S.R. Srikant
Fine Structure Analysis Of 4702 ^Oa Band Of The Molecule, M.B. Sureshkumar, S.R. Srikant
Turkish Journal of Physics
The emission spectrum of the cobalt monochloride molecule has been excited in a high frequency discharge tube source and the (0,0) band of H-system at 4702 \AA was photo-graphed at an inverse dispersion of 0.973 \AA/mm in the 5th order of a two meter plane grating spectrograph (Carl-Zeiss). The fine structure analysis of the band has been carried out and the molecular constants are reported for the first time. Rotational isotopic shift due to $^{37}$Cl support the analysis. The electronic transition involved is of the type $0^-$----- $0^-$ of case (c) which is equivalent of $^{3}\sum^{+}$-----$^{3}\sum^+$ or $^5\sum^+$-----$^5\sum^+$.
A Study Of The Linbo_3 And Litao_3 Absorption Edge, S. Çabuk, A. Mamedov
A Study Of The Linbo_3 And Litao_3 Absorption Edge, S. Çabuk, A. Mamedov
Turkish Journal of Physics
Optical spectroscopy methods are used to study the spectra of some oxygen-octahedral ferroelectrics - $LiNbO_3$ and $LiTaO_3$. Study of the role of $BO_6$ octahedron by using spectroscopic methods can cast light on the many physical phenomena that place in $LiNbO_3$ and $LiTaO_3$. For these crystals, absorption edge, band gap, Urbach constants and phonon energy were found.
A Study On The Effect Of Ni Dopping On Bi-Pb-Sr-Ca-Cu-O System, M. Tepe, D. Abukay
A Study On The Effect Of Ni Dopping On Bi-Pb-Sr-Ca-Cu-O System, M. Tepe, D. Abukay
Turkish Journal of Physics
The effect of $Ni$ doping on superconductivity properties of the $Bi_{1.7}Pb_{0.3}Sr_2Ca_2(Cu_{1-x}Ni_x)_3O_y$ system has been investigated by means of $x$-ray diffraction, ac electrical resistance, ac magnetic susceptibility and critical current measurements. The volume fraction of the 2223 phase decreases with increasing $Ni$ concentration. The zero-resistance temperature and the critical current density are suppressed with $Ni$ substitution.
Characterization Of Sb Doped Y Bacuo Superconducting Ceramics, K. Kocabaş, N. Kazanci, M. Tepe
Characterization Of Sb Doped Y Bacuo Superconducting Ceramics, K. Kocabaş, N. Kazanci, M. Tepe
Turkish Journal of Physics
In this study the structural characteristics of $Sb_2O_3$ doped $YBa_2Cu_3O_{7-x}$ superconductive ceramics are investigated by electrical and XRD analyses. It is determined that, while in undoped specimens the value of $T_c$ is equal to 92 K, this value is negatively influenced by the addition of $Sb$. Structural phase results obtained from XRD analysis confirm the result obtained from the electrical measurements.
Microscopic Calculations Of The Nucleus-Nucleus Optical Potential, M. M. Osman
Microscopic Calculations Of The Nucleus-Nucleus Optical Potential, M. M. Osman
Turkish Journal of Physics
In present work, a density dependent nucleon-nucleon interactions based on the $G$-matrix elements of the Paris nucleon-nucleon potential have been used to calculate the real part of the nucleus-nucleus optical potential. We have compared our results with those deduced from experiment. We found that our results, obtained using a suitable approximation of the kinetic energy density, agree satisfactory with those extracted from experiment at the strong absorption radius. Moreover, the higher values of the compressibility, $K$, agree better with experiment than the lower values.
Remote Sensing And Synchronous Land Surface Measurements Of Soil Moisture And Soil Temperature In The Field, N.V. Kolev, K.P. Penev, Y.M. Kirkova, B.S. Krustanov, T.G. Nazarsky, G.K. Dimitrov, C.P. Levchev, H.I. Prodanov, L.H. Kraleva
Remote Sensing And Synchronous Land Surface Measurements Of Soil Moisture And Soil Temperature In The Field, N.V. Kolev, K.P. Penev, Y.M. Kirkova, B.S. Krustanov, T.G. Nazarsky, G.K. Dimitrov, C.P. Levchev, H.I. Prodanov, L.H. Kraleva
Turkish Journal of Physics
The paper presents the results of remote sensing and synchronous land surface measurements for estimation of soil (surface and profile) water content and soil temperature for different soil types in Bulgaria. The relationship between radiometric temperature and soil surface water content is shown. The research is illustrated by some results from aircraft and land surface measurements carried out over three test areas near Pleven, Sofia and Plovdiv, respectively, during the period 1988-1990.
Deformation Methods For Investigation Of The Deep Level Parameters In Semiconductors, S. Z. Zainabidinov, A. Abduraimov, O. O. Mamatkarimov, I.G. Tursunov, R.Kh. Khamidov
Deformation Methods For Investigation Of The Deep Level Parameters In Semiconductors, S. Z. Zainabidinov, A. Abduraimov, O. O. Mamatkarimov, I.G. Tursunov, R.Kh. Khamidov
Turkish Journal of Physics
In this paper deformation methods are offered to investigate deep level parameters in semiconductors. It is based on strain parameters measurements of compensated and overcompensated semiconductors. The dynamic changes of current flow in compensated and overcompensated samples of $p$-type $Si: Ni$ and $n$-type $Si: Mn$ under uniform pulse hydrostatic compression (UHC) was investigated. It was observed that in $p$-type $Si: Ni$ samples ionization energy levels $Ni$ at UHC increases, on the contrary in samples $n$-type $Si: Mn$ it decreases. The ionization energy and baric coefficient of the shift of $Ni$ and $Mn$ levels were bounded.
Modelling Of Radiation Regime Receiver Cavities Of Solar Power Plants, Eduard Avanesov, Nina Berezhnaya
Modelling Of Radiation Regime Receiver Cavities Of Solar Power Plants, Eduard Avanesov, Nina Berezhnaya
Turkish Journal of Physics
In this work, we develop a model for radiant heat transfer calculations inside spherical and cylindrical spaces. The analysis of the possibility of mirror cone subreflector applications for uniform flux density attainment is carried out. A procedure optimizing equiilluminate space forming a search for an indicatrix's composition is developed.
Anomalous Electrical Characteristics Of Ion Implanted P^+-N Juntions, N. Siddiqui
Anomalous Electrical Characteristics Of Ion Implanted P^+-N Juntions, N. Siddiqui
Turkish Journal of Physics
Electrical characteristics of three $P^+ - n$ diodes fabricated on high resistivity silicon by ion implantation technique are studied by making capacitance-voltage (C-V), reverse current-voltage (I-V) and dielectric spectroscopy of semiconductor (DSS) measurements. The C-V characteristics show abrupt fall in capacitance, while I-V characteristics show abrupt rise in current at the same voltages as in the C-V characteristics. These abrupt discontinuities are ascribed to the formation of defect clusters in the lightly doped base regions where charge transfer might be taking place by thermally assisted tunneling. Low activation energies obtained in the DSS measurements also point toward the same mechanism.
Electro-Optic Response Of A Polymer Dispersed Liquid Crystal Film, Rıdvan Karapinar
Electro-Optic Response Of A Polymer Dispersed Liquid Crystal Film, Rıdvan Karapinar
Turkish Journal of Physics
Polymer dispersed liquid crystal (PDLC) films are potentially useful in electro-optic devices since they can be used for vision products. In this work the PDLC thin films were prepared by a photopolymerization induced phase separation method and electro-optic properties of the films were investigated.
Reorientation Of Magnetization In Thin Films, Bengü Kaplan
Reorientation Of Magnetization In Thin Films, Bengü Kaplan
Turkish Journal of Physics
The spin wave energy is determined by the competition between uniaxial and cubic anisotropy. We discuss the reorientation temperature $ T_{R} $ of magnetization in two-dimension and calculate its dependence on the exchange, $J$, and the uniaxial anisotropy, $G$, parameters within random phase approximation. We find that $ T_{R} $ varies as $ \sqrt{JG} $ in the planar regime.
Photoconductivity Studies Of Crystalline Si:H P-I-N, Ruhi Kaplan, Bengü Kaplan
Photoconductivity Studies Of Crystalline Si:H P-I-N, Ruhi Kaplan, Bengü Kaplan
Turkish Journal of Physics
Optically modulated photoconductivity (PC) properties of hydrogenated crystalline silicon (c-Si:H) with p-i-n junctions were investigated by frequency-resolved spectroscopy in the temperature range 20-290 K. The PC lifetime measurements of c-Si:H p-i-n show a second lifetime distribution which only dominates at low temperature under low illumination levels of excitation. Unlike the room temperature single lifetime distribution seen in c-Si:H p-i-n, the maximum of this second lifetime distribution shifts to longer times when the excitation intensity decreases, which reconciles with non-geminate pair recombination and thus the distant-pair model. In addition to lifetime measurements, the direct current-voltage (I-V) characteristics, the excitation light intensity- …
The Image Reconstruction By Photocounts Triple Correlations, R. R. Vildanov, M. S. Ismatov, N. Z. Kodirov, A. T. Mirzaev, A. N. Yakubov
The Image Reconstruction By Photocounts Triple Correlations, R. R. Vildanov, M. S. Ismatov, N. Z. Kodirov, A. T. Mirzaev, A. N. Yakubov
Turkish Journal of Physics
An optoelectronic system is constructed for the recording of the triple correlation function for radiation intensity being detected in a photon counting operation. The results of the investigation show the possibility an image reconstruction for faint objects from the derivation of comprehensive information related to the coherence function.
Optical Anisotropy Of Iron Garnets With Growing Anisotropy, Odil Ochilov
Optical Anisotropy Of Iron Garnets With Growing Anisotropy, Odil Ochilov
Turkish Journal of Physics
The theoretical analysis of the position of principal diachronic directions at magnetization rotation in (100) and (110) planes for the case of growing dichroism axes in random directions was made. The calculations of angular dependencies of dichroic axes (DA) position for different values of the magneto-optical anisotropy parameter, a, have been done. The relations between the growing and magneto-optical dichroism, K/M, and the angle \delta characterizing the direction of principal growing dichroism axes were given. The angular dependences of DA position in epitaxial iron garnet films have been investigated experimentally. The measurements at the different light wavelengths permitted one to …
Analytical Expressions Of Matrix Elements For Saxon-Woods Potential And Pad'{E} Approximations, Valentin L. R. Niculescu, Dumitru Catana
Analytical Expressions Of Matrix Elements For Saxon-Woods Potential And Pad'{E} Approximations, Valentin L. R. Niculescu, Dumitru Catana
Turkish Journal of Physics
The paper presents the analytical matrix elements of the kinetic hamiltonian in the oscillator base. The Pad'{e} approximations for the potential part (Saxon - Woods and alike) was used. From residue calculus the potential matrix elements are analytical. Many parts of these expressions can be computed once for ever. In this way the evaluation time can be reduced and the relations obtained are well suited for parallel computation.
Alloying Of Aisi 1008 Steel Surfaces By 10ms Nd: Yag Laser Pulses, Raid A. İsmai̇l
Alloying Of Aisi 1008 Steel Surfaces By 10ms Nd: Yag Laser Pulses, Raid A. İsmai̇l
Turkish Journal of Physics
Hardened surfaces were produced on AISI 1008 steel through a laser surface alloying (LSA) technique. Mixture of pure Boron, Silicon, and Carbon powders of the same grain size were deposited on the substrate. The surface was then melted using pulsed Nd:YAG laser (\tau = 10 ms) at an energy of 12 J. The influence of alloying elements on the microstructure and hardness of treated layer was investigated. Dependending on the alloying elements species, different maximum surface hardness, different maximum depth, and different hardness profile could be obtained. The B+Si alloyed zone exhibited maximum hardness to a nominal alloying depth of …
Infrared Absorption Study Of Potassium-Boro-Vanadate-Iron Glasses, Dinesh K. Kanchan, Harshvadan R. Panchal
Infrared Absorption Study Of Potassium-Boro-Vanadate-Iron Glasses, Dinesh K. Kanchan, Harshvadan R. Panchal
Turkish Journal of Physics
The IR studies have been made in the K_2O-B_2O_3-V_2O_5-Fe_2O_3 glass system. The increase in intensity and shifting of vibrational bands towards lower wave number at 1400-1350 cm^{-1}, 1200 cm^{-1} and 100-940 cm^{-1} in IR spectra have been ascribed to the formation of BO_3 to BO_4 and VO_5 to VO_4 tetrahedra along with the formation of non-bridging oxygens attached to boron and vanadium. In heat-treated glass samples, many new vibrational bands have been observed which were however, absent in the untreated samples. The preservation of the 1020 cm^{-1} band assigned to V=O bond suggests that K_2O shows the preference for borate …
Domain Structures Of Epitaxial Perovskite Ferroelectric Films: Part Ii. Applications, S. Pamir Alpay, Alexander L. Roytburd
Domain Structures Of Epitaxial Perovskite Ferroelectric Films: Part Ii. Applications, S. Pamir Alpay, Alexander L. Roytburd
Turkish Journal of Physics
The use of domain stability maps for epitaxial perovskite ferroelectric films is illustrated with some examples. The equilibrium domain structure and domain fractions as a function of temperature are predicted for PbTiO_3(001) films grown epitaxially on three different substrates: MgO(001), KTaO_3(001), and SrTiO_3(001). Misfit dislocation formation at the growth temperature is found to have a profound effect on both the domain selection and relative domain populations. Theoretical predictions are compared with available experimental data.
Compositional Dependence Of Properties Of Rf-Sputtered Bi-Sr-Ca-Cu-O Thin Films, Ayhan Güldeste
Compositional Dependence Of Properties Of Rf-Sputtered Bi-Sr-Ca-Cu-O Thin Films, Ayhan Güldeste
Turkish Journal of Physics
Compositional dependence of superconducting transition temperature (T_c) of Bi_2Sr_{3-x}Ca_xCu_2O_{8+x} thin films grown by rf sputtering on single crystal MgO substrates has been investigated. Films have been assessed by considering their initial composition in terms of (Ca+Sr)/Bi ratio with their atomic concentration normalized to Cu:2. It was found that T_{c-zero} of around 80K is achievable for (Ca+Sr)/Bi ratio between 1.4 and 1.65, while T_{c-onset} remains above 90K. Quenching from high temperature increased T_{c-zero,} but it may result in a deterioration in resistivity due to micro cracks induced by the thermal stress.
Electronic Structure Of Optimized Si_{M}H_{N} Clusters: Mindo3 And Am1 Calculations, Şakir Erkoç, Lemi Türker
Electronic Structure Of Optimized Si_{M}H_{N} Clusters: Mindo3 And Am1 Calculations, Şakir Erkoç, Lemi Türker
Turkish Journal of Physics
We have investigated the electronic structure of optimized hydrogenated silicon microclusters. Si_{m}H_{n} (m=2,3,5,6; n = 4,6) have been investigated. The calculations were performed using both MINDO3 and AM1 semiempirical molecular orbital methods.
A Mean Field Model With Two Order Parameters For Three-Phase Coexistence Near The Tricritical Point, S. Sali̇hoğlu
A Mean Field Model With Two Order Parameters For Three-Phase Coexistence Near The Tricritical Point, S. Sali̇hoğlu
Turkish Journal of Physics
This study gives a mean field model with two order parameters for three-phase coexistence near the multicritical point. The critical exponents calculated from our model are the tricritical exponents for the order parameters, susceptibility and the specific heat. Hence, our mean field model describes adequately the tricritical behaviour of a system in the region of three-phase coexistence.
Numerical Calculation Of Energy Loss Rate For E^+ + E^- \Rightarrow \Nu + \Bar{\Nu} Process, A. Aydemir
Numerical Calculation Of Energy Loss Rate For E^+ + E^- \Rightarrow \Nu + \Bar{\Nu} Process, A. Aydemir
Turkish Journal of Physics
The energy loss rate for pair annihilation is calculated numerically in V-A (Fermi theory) and Weinberg-Salam (Standard theory) theories, taking into account also the variation of density at various temperatures using the results obtained in closed form by Chiu, and Schinder, et al. The calculations made by Chiu, and Salpeter, et al., are seen to be parallel to each other. Dicus has calculated energy loss rate for this process only for a few limiting cases since the integrals can not be taken analytically for all \lambda and \nu. The graph drawn for the values we obtained is compared with the …