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Citation - WoS: 5
Citation - Scopus: 5
Dispersive Optical Constants of Tl₂ingase_{4< Single Crystals}
(Iop Publishing Ltd, 2007) Qasrawi, A. F.; Gasanly, N. M.
The structural and optical properties of Bridgman method grown Tl2InGaSe4 crystals have been investigated by means of room temperature x-ray diffraction, and transmittance and reflectance spectral analysis, respectively. The x-ray diffraction technique has shown that Tl2InGaSe4 is a single phase crystal of a monoclinic unit cell that exhibits the lattice parameters of a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees . The optical data have revealed an indirect allowed transition band gap of 1.86 eV. The room temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as 28.51 and 3.45 eV, 9.26 and 3.04, respectively.
Citation - WoS: 2
Citation - Scopus: 2
Electron-Lattice Interaction Scattering Mobility in Tl₂ingase_{4< Single Crystals}
(Iop Publishing Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.
In this work, the dark electrical resistivity, charge carrier density and Hall mobility of Tl(2)InGaSe(4) single crystal have been recorded and analyzed to investigate the dominant scattering mechanism in the crystal. The data analyses have shown that this crystal exhibits an extrinsic n-type conduction. The temperature-dependent dark electrical resistivity analysis reflected the existence of two energy levels as 0.396 and 0.512 eV, being dominant above and below 260 K, respectively. The temperature dependence of the carrier density was analyzed by using the single-donor-single-acceptor model. The latter analysis has shown that the above maintained 0.512 eV energy level is a donor impurity level. The compensation ratio for this crystal is determined as 0.96. The Hall mobility of Tl(2)InGaSe(4) is found to be limited by the scattering of electron-acoustic phonon interactions. The calculated theoretical acoustic phonon scattering mobility agrees with the experimental one under the condition that the acoustic deformation potential is 12.5 eV.
Citation - WoS: 3
Citation - Scopus: 3
Optoelectronic Properties of Ga₄se_{3< Single Crystals}
(Iop Publishing Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.; Ilaiwi, K. F.
The optoelectronic properties of Bridgman method-grown Ga(4)Se(3)S single crystals have been investigated by means of room temperature electrical resistivity, temperature-dependent photosensitivity and temperature-dependent optical absorption. The photosensitivity was observed to increase with decreasing temperature, the illumination dependence of which was found to exhibit monomolecular recombination in the bulk at 300 K. The absorption coefficient, which was calculated in the incident photon energy range of 2.01-2.35 eV, increased with increasing temperature. Consistently, the absorption edge shifts to lower energy values. The fundamental absorption edge corresponds to an indirect allowed transitions energy gap (2.08 eV at 300 K) that exhibits a temperature coefficient of -95 x 10(-4) eVK(-1).
Citation - WoS: 7
Citation - Scopus: 7
Phase-dependent characteristics of a superconducting junction by using the Schrodinger wave function
(Iop Publishing Ltd, 2007) Canturk, M.; Kurt, E.
As a macroscopic quantum system, superconducting junction devices are considered both analytically and numerically with the help of the Schrodinger wave equation. Considering the Cooper pair wave function psi in a time-dependent nature, the Hamiltonian of the system is constructed. The phase difference theta is assumed to be a unique independent variable of the superconducting junction in order to evaluate the characteristics of the system. The probability rho(theta) and super current j(theta) densities are determined for different applied voltages V. It is observed that both the amplitude and the period of the wave function psi(theta) have indicated different behaviors as functions of theta for various cases of V. Similarly, rho and j reflect drastic changes. It is shown that numerical results are in good agreement with the analytic results. Our results indicate consistency with some earlier experimental studies for different superconducting devices.
Citation - WoS: 13
Citation - Scopus: 13
Light Illumination Effect on the Electrical and Photovoltaic Properties of In₆s_{7< Crystals}
(Iop Publishing Ltd, 2006) Qasrawi, AF; Gasanly, NM
The electrical and photoelectrical properties of In6S7 crystals have been investigated in the temperature regions of 170-300 K and 150-300 K, respectively. The dark electrical analysis revealed the intrinsic type of conduction. The energy band gap obtained from the temperature-dependent dark current is found to be 0.75 eV. It is observed that the photocurrent increases in the temperature range of 150 K up to T-m = 230 K and decreases at T > T-m. Two photoconductivity activation energies of 0.21 and 0.10 eV were determined for the temperature ranges below and above Tm, respectively. The photocurrent (I-ph)-illumination intensity (F) dependence follows the law I-ph alpha F-gamma. The value of. decreases when the temperature is raised to T-m, then it starts increasing. The change in the value. with temperature is attributed to the exchange in role between the recombination and trapping centres in the crystal. The crystals are found to exhibit photovoltaic properties. The photovoltage is recorded as a function of illumination intensity at room temperature. The maximum open-circuit voltage and short-circuit photocurrent density, which are related to an illumination intensity equivalent to one sun, are 0.12 V and 0.38 mA cm(-2), respectively.
Citation - WoS: 8
Citation - Scopus: 8
Photoelectronic and Electrical Properties of Ins Crystals
(Iop Publishing Ltd, 2002) Qasrawi, AF; Gasanly, NM
To identify the localized levels in InS single crystals, the dark electrical conductivity, current-voltage characteristics and photoconductivity measurements were carried out in the temperature range of 10-350 K. Temperature dependence of dark electrical conductivity and the space-charge limited current studies indicate the presence of a single discrete trapping level located at (10 +/- 2) meV below the conduction band with a density of about 4.8 x 10(11) cm(-3). The conductivity data above 110 K reveal an additional two independent donor levels with activation energies of (50 +/- 2) and (164 +/- 4) meV indicating the extrinsic nature of conductivity. The spectral distribution of photocurrent in the photon energy range of 0.8-3.1 eV reveals an indirect band gap of (1.91 +/- 0.04) eV. The photocurrent-illumination intensity dependence follows the law I-ph proportional to F-gamma, with gamma being 1.0 and 0.5 at low and high illumination intensities indicating the domination of monomolecular and bimolecular recombination, respectively. It is observed that the photocurrent increases in the temperature range of 10 K up to T-m = 110 K and decreases or remains constant for 110 K < T < 160 K and increases again above 160 K. The temperature dependence of the photocurrent reveals an additional shallow impurity level with activation energies of 3 meV.
Citation - WoS: 11
Citation - Scopus: 11
Dispersive Optical Constants and Temperature-Dependent Band Gap of Cadmium-Doped Indium Selenide Thin Films
(Iop Publishing Ltd, 2005) Qasrawi, AF; Department of Electrical & Electronics Engineering
Polycrystalline cadmium-doped indium selenide thin films were obtained by the thermal co-evaporation of alpha-In2Se3 crystals and Cd onto glass substrates kept at a temperature of 200 degrees C. The temperature dependence of the optical band gap in the temperature region of 300-450 K and the room temperature refractive index, n(lambda), of these films have been investigated. The absorption edge shifts to lower energy as temperature increases. The fundamental absorption edge corresponds to a direct energy gap that exhibits a temperature coefficient of -6.14 x 10(-4) eV K-1. The room temperature n(lambda) which was calculated from the transmittance data allowed the identification of the oscillator strength and energy, static and lattice dielectric constants and static refractive index as 20.06 and 3.07 eV, 7.43 and 10.52 and 2.74, respectively.
Developments in Technology-Based Courses Contents of Interior Architecture Departments in Turkey
(Iop Publishing Ltd, 2020) Aykac, Gokce Nur
The introduction of information technologies in space design disciplines begins with the use of the Computer Aided Design concept in those disciplines. Since the first example of CAD tool which was launched in 1963, the ability to design using computers has been a method adopted by architecture and space design disciplines and transferred to the educational context. There were changes and transformations in this method due to the needs created by the developing building technologies. The CAD technology, has been adopted to the space design education in order to support the courses. The CAD which was created for challenging the difficulties in the practicing area and speeding up the process, also takes place among the traditional methods of space design in the Interior Architecture discipline. The possibilities provided by those digitally created spatial mediums, have led to a rotational improvement in both education and practice. In addition, the reflections of technological developments in the social context in last decade on many areas of life have led to the necessity of reorganizing the educational contents. Academic studies conducted in recent years, are designed to include the last technological developments in today's educational contents and to reflect students' interests and commitment to these technologies in direct proportion. Bearing this in mind, the objective of this study is to read out the reflection of the developments mentioned above on the Interior Architecture discipline in Turkey by monitoring the developments in the context of the need of updating the educational contents. In order to meet the social developments and today's skills, space design education must follow the technological context in parallel. Based on these considerations, the studies of Turkey which were examined in this research have been conducted before could be explained as inadequate. In this context, to examine the curriculum of the Interior Architecture departments of Turkey and to monitor the updates mentioned before constitute the main focus of the study. CAD-based courses in the curriculum of the Interior Architecture departments were determined and the contents were examined. These analyses were achieved in the context of the methods, techniques and tools used in the courses, and after, the situation of the information based courses were determined. It was concluded that these courses were transformed in direct proportion in line with the increasing needs in the educational context with the developing technology and updates should continue in the context of meeting today's skills.
Citation - WoS: 8
Citation - Scopus: 8
Temperature- and Photo-Excitation Effects on the Electrical Properties of Tl₄se_{3< Crystals}
(Iop Publishing Ltd, 2009) Qasrawi, A. F.; Gasanly, N. M.
The extrinsic energy states and the recombination mechanism in the Tl4Se3S chain crystals are being investigated by means of electrical and photoelectrical measurements for the first time. The electrical resistivity is observed to decrease exponentially with increasing temperature. The analysis of this dependence revealed three impurity levels located at 280, 68 and 48 meV. The photocurrent is observed to increase as temperature decreases down to a minimum temperature T-m=200 K. Below this temperature the photocurrent decreases upon temperature lowering. Two photoconductivity activation energies of 10 and 100 meV were determined for the temperature ranges below and above T-m, respectively. The photocurrent (I-ph) versus illumination intensity (F) dependence follows the I-ph proportional to F-gamma law. The value of gamma decreases from similar to 1.0 at 300K to similar to 0.34 at 160K. The change in the value of gamma with temperature is attributed to the exchange of roles between the monomolecular recombination at the surface near room temperature and trapping centers in the crystal, which become dominant as temperature decreases.
Citation - WoS: 4
Citation - Scopus: 4
A Material Perspective on Consequence of Deformation Heating During Stamping of Dp Steels
(Iop Publishing Ltd, 2017) Simsir, C.; Cetin, B.; Efe, M.; Davut, K.; Bayramin, B.
Recent studies showed that, during stamping of high strength steels at industrially relevant production rates, local temperature in the blank may rise up to 200 degrees C - 300 degrees C due to deformation heating. Moreover, die temperature may also rise up to 100 degrees C - 150 degrees C for progressive stamping dies. Based on the common assumption that the blank softens as the temperature increases, thermal softening creates a margin in Forming Limit Diagram (FLD) and therefore the FLD determined at room temperature can safely be used for those cases. In this article, the validity of this assumption on DP590 steel is questioned by high temperature tensile tests (RT - 300 degrees C) at various strain rates (10(-3) s(-1) - 1 s(-1)). The results indicated a decrease both in uniform and total elongation in 200 degrees C - 300 degrees C range together with several other symptoms of Dynamic Strain Aging (DSA) at all strain rates. Concurrent with the DSA, the simulated FLD confirms the lower formability at high temperature and strain rates. Thus, it is concluded FLD determined at RT may not be valid for the investigated steels.

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