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Articles 1321 - 1332 of 1332
Full-Text Articles in Physics
Low-Temperature Phase Transition In Tl In Se_{2} Crystals, Oktay Zeynelabidin O Alekperov, Mazahir Amirjan Oglu Aljanov, Elmira M. Ali Gizi Keri̇mova
Low-Temperature Phase Transition In Tl In Se_{2} Crystals, Oktay Zeynelabidin O Alekperov, Mazahir Amirjan Oglu Aljanov, Elmira M. Ali Gizi Keri̇mova
Turkish Journal of Physics
Heat capacity, lattice parameter, spectral and temperature dependences of photoconductivity of chained crystal Tl In Se_{2} have been investigated in this work. For the first time, it has been found that the phase transtion takes plase at temperatures 135 and 184 K in this crystal. The changes of heat capacity, photoconductivity and lattice parameter of Tl In Se_{2} in the region of phase transition is supposed to be connected with the presence of an incommensurate phase in this crystal.
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.
A Phase Diagram Of The Nematic, Smectic A And Smectic C Phases In Liquid Crystals, S. Sali̇hoğlu, H. Yurtseven
A Phase Diagram Of The Nematic, Smectic A And Smectic C Phases In Liquid Crystals, S. Sali̇hoğlu, H. Yurtseven
Turkish Journal of Physics
In this study we have obtained a phase diagram for the nematic, smectic A and smectic C phases in liquid crystals. For this phase diagram we have studied two different mean field models for a mixture of liquid crystalline system. In our first model we consider the NC and AC transitions as first order, and the NA transition as a second order. In our second model we consider the NC and NA transitions as first order, and the AC transition as a second order.
A Mean Field Model For The Coexistence Of Nematic, Smectic A And Smectic C Phases In Liquid Crystals, H. Yurtseven, S. Sali̇hoğlu
A Mean Field Model For The Coexistence Of Nematic, Smectic A And Smectic C Phases In Liquid Crystals, H. Yurtseven, S. Sali̇hoğlu
Turkish Journal of Physics
We present here a mean field model for the nematic-smectic A-smectic C coexistence of a liquid crystal near the NAC point which is a multicritical point. The critical exponents calculated from our model are tricritical expoenents for the order parameters, susceptibility and the specific heat. Our results show that if the NAC point is the tricritical point, then our mean field model describes adequately the liquid crystalline system in the coexistence region of the nematic-smectic A-smectic C phases.
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 …
The Effect Of Spatially Dependent Screening On The Donor Ionization Energy In A Quantum Wire, B.N. Onwuagba
The Effect Of Spatially Dependent Screening On The Donor Ionization Energy In A Quantum Wire, B.N. Onwuagba
Turkish Journal of Physics
The effect of the spatially dependent screening on the ionization energy of a shallow donor in a 1D quantum well wire made of Ga_{1-x}Al_x/GaAs superlattice is presented. A variational approach is used to obtain ionization energy of the on-centre impurity at the origin of the well and the results obtained are compared with the existing values.
Doping Effects Of Ga And Te On The Kinetic Coefficients Of Rhombohedral And Cubic Phases Of Ge_{1-X} Ga_X Te Solid Solution Alloys, T. Atalay, M.H. Akperov
Doping Effects Of Ga And Te On The Kinetic Coefficients Of Rhombohedral And Cubic Phases Of Ge_{1-X} Ga_X Te Solid Solution Alloys, T. Atalay, M.H. Akperov
Turkish Journal of Physics
In this study Ga and Te doping effects on the kinetic parameters (thermo e.m.f., electrical conductivity, heat conductivity, Hall and Nernst-Ettingshausen coefficients) of the rhombohedral and cubic phases of Ge_{1-x} Ga_x Te (0 < x \leq 0,06) solid solutions has been investigated between 77-900 K temperature intervals. Increase in the amount of Te increases hole concentration and reduces lattice constant, whereas rhombohedral propeties of GeTe rises with increase of Ga concentration. The observed anomalies on the kinetic parameters may be explained qualitatively by the complexity of the Fermi surface shape and the zone model of GeTe which involves the seperation of the L extremums that is same for ``\alpha'', ``\beta'' and ``\gamma'' phases of the compound.
^{19}F Nmr Study Of Flux-Line Dynamics In Fluorinated Yba_2cu_4o_8, Figen Tabak, Mavrizio Corti̇
^{19}F Nmr Study Of Flux-Line Dynamics In Fluorinated Yba_2cu_4o_8, Figen Tabak, Mavrizio Corti̇
Turkish Journal of Physics
Measurements of the ^{19}F NMR linewidth \Delta \nu and spin-lattice relaxation rate 1/T_1 have been performed in an oriented powder sample of fluorinated YBa_2Cu_4O_8 at temperatures 4 < T < 300 K and static magnetic fields 0.3 < H_0 < 9.4 T for Hollc. Thermal motion of flux lines was evidenced from the effect on NMR linewidth while 1/T_1 showed the effects due to interaction with Fermi liquid.
Coulomb Breakup Of Nucleus ^6 Li On Ion ^{208}Pb, B. F. Irgaziev, H. T. Ergashbaev
Coulomb Breakup Of Nucleus ^6 Li On Ion ^{208}Pb, B. F. Irgaziev, H. T. Ergashbaev
Turkish Journal of Physics
In the framework of the three-body approach the A(a,bc)A Coulomb breakup has been investigated. The three-body Coulomb dynamic is taken into account to derive the expression for the reaction matrix element. The mechanism of the breakup includes the direct process and the excitation of resonance state of the particle a. The calculation of the triple differential cross section of the ^{208}Pb(^6Li, \alpha d)^{208}Pb Coulomb dissociation have been performed in the energy region E_{\alpha d} < 1MeV. Calculations for the Coulomb dissociation ^{208}Pb(^6Li, \alpha d)^{208}Pb, including consideration of the triple cross section going through the first resonance of ^6Li have been performed. The results of the calculations are compared with experimental data.
Formation Of Hot Zone By The Application Of An Electric Field To Superconducting Bi_{1.6}Pb_{0.4}Sr_2ca_3cu_4o_X (2234) Rod, E. Yanmaz
Turkish Journal of Physics
The formation of hot zone by electric field on superconducting Bi-Pb-Sr-Ca-Cu-O (BSCCO) rods is described. Bulk samples with a nominal composition of Bi_{1.6}Pb_{0.4}Sr_2Ca_3Cu_4O_x (2234) were prepared as rods by a melt casting process. An electrical field was applied to the BSCCO rods and this current caused the resistance of the rod to fall and after a few minutes the initial voltage fell while the current was increased to 2.5A. Under certain conditions, a well-defined hot zone formed at the positive electrode, travelled along the rod and eventually disappeared on reaching the negative electrode. A small increase in the applied current …