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Article Citation - WoS: 11Citation - Scopus: 11Microstructural, thermal, and electrical properties of Bi1.7V0.3Sr2Ca2Ca3Ox glass-ceramic superconductor(Wiley-v C H verlag Gmbh, 2004) Kayed, TS; Calinli, N; Aksu, E; Koralay, H; Günen, A; Ercan, I; Cavdar, SA glass-ceramic Bi1.7V0.3Sr2Ca2Cu3Ox superconductor was prepared by the melt-quenching method. The compound was characterized by scanning electron microscopy, x-ray diffraction, differential thermal analysis, current-voltage characteristics, transport resistance measurements, and Hall effect measurements. Two main phases (BSCCO 2212 and 2223) were observed in the x-ray data and the values of the lattice parameters quite agree with the known values for 2212 and 2223 phases. The glass transition temperature was found to be 426 degreesC while the activation energy for crystallization of glass has been found to be E-a = 370.5 kJ / mol. This result indicates that the substitution of vanadium increased the activation energy for the BSCCO system. An offset T-c of 80 K was measured and the onset T-c was 100 K. The Hall resistivity rho(H) was found to be almost field-independent at the normal state. A negative Hall coefficient was observed and no sign reversal of rho(H) or RH could be noticed. The mobility and carrier density at different temperatures in the range 140-300 K under different applied magnetic fields up to 1.4 T were also measured and the results are discussed.Article Citation - WoS: 9Citation - Scopus: 9Electrical Properties of Bi1.5znsb1.5< Pyrochlore Ceramics(Wiley-v C H verlag Gmbh, 2003) Kayed, TS; Mergen, ABi1.5ZnSb1.5O7 pyrochlore samples were prepared by solid state reaction method. They were examined by x-ray diffraction and scanning electron microscopy. Single phase, belongs to the cubic pyrochlore structure, with a lattice parameter of 10.442 Angstrom and grain size that varies from 16 to 20 mum was obtained. The electrical properties were measured at different temperatures in the range 15-330 K under different applied magnetic fields up 1.4 T. In our measurements for Hall coefficient, Hall resistivity, and mobility; we noticed an anomalous behavior at two temperatures (around 250 and 310 K) which was supported by the I-V measurements (double transition of the slope of I-V characteristics (beta) at the same temperatures). This was discussed in terms of polarization phenomenon and mixed ionic-electronic conduction. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Article Citation - WoS: 6Citation - Scopus: 8Temperature and Magnetic Field Effects on the Carrier Density and Hall Mobility of Boron-Doped Tl-Ba Superconductor(Elsevier Science Sa, 2005) Kayed, TS; Qasrawi, AFBoron-doped T1-based superconductor was prepared by adding an amount of 1 wt.% B to the Tl1.8Ba2Ca2.2Cu3Ox, compound. The usual solid-state reaction method has been applied under optimum conditions. The X-ray data of the sample show a tetragonal structure with a high ratio of T1-2223 superconducting phase. The sample showed a transition at 125 K and the zero resistance was observed at 120 K. The magnetic field and temperature effects on the normal state electrical resistivity, carrier density, and Hall mobility have been investigated. Both temperature and magnetic field significantly affect the resistivity behavior. The zero field resistivity was found to vary exponentially with temperature with a slope revealing activation energy of 27.5 meV. When the magnetic field is applied, the resistivity varied up-normally in the temperature region of 160-240 K. The temperature dependent carrier concentration calculated from the Hall coefficient data varied linearly with the applied magnetic field. This effect was attributed to the increase in the hole effective mass upon field increment. The temperature-dependent carrier concentration data at several applied fields were analyzed by the single donor-single acceptor model to obtain the values of effective masses. The temperature and magnetic field dependent normal state Hall mobility was found to be limited by the scattering of acoustic phonons. (c) 2005 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Optoelectronic Properties of Tl3inse4 Single Crystals(Taylor & Francis Ltd, 2010) Qasrawi, A. F.; Gasanly, N. M.The crystal structure, temperature-dependent electrical conductivity, Hall coefficient, current-voltage characteristics, absorption spectra and temperature- and illumination-dependent photoconductivity of Tl3InSe4 single crystals were investigated. Tl3InSe4 crystallises in a body-centred lattice with tetragonal symmetry and belongs to the space group [image omitted]. The crystals are extrinsic p-type semiconductors and exhibit a conductivity conversion from p- to n-type at a critical temperature, Tc, of 283 K. They are observed to have Schottky diode properties in an Ag/Tl3InSe4/Ag Schottky barrier device structure. The absorption spectra displays two maxima, one related to an indirect energy band gap of 1.20 eV and another corresponding to exciton transitions. The photocurrent is observed to be strongly affected by the conductivity type of the crystal. The incident light intensity dependence of the photocurrent is found to be supralinear, linear and sublinear, indicating strong recombination at the surface, monomolecular recombination and bimolecular recombination, respectively, in the regions where the sample is p-type ([image omitted]), at [image omitted], and in the n-type region ([image omitted]). In the n-type region, the photocurrent increases with decreasing temperature down to 250 K, below which the photocurrent is temperature invariant. The change in recombination mechanism is attributed to the change in the behaviour of sensitising and recombination centres.Article Citation - WoS: 21Citation - Scopus: 22Investigation of Carrier Scattering Mechanisms in Tiins2 Single Crystals by Hall Effect Measurements(Wiley-v C H verlag Gmbh, 2004) Qasrawi, AF; Gasanly, NMTlInS2 single crystals are studied through the conductivity and Hall effect measurements in the temperature regions of 100-400 and 170-400 K, respectively. An anomalous behavior of Hall voltage, which changes sign below 315 K, is interpreted through the existence of deep donor impurity levels that behave as acceptor levels when are empty. The hole and electron mobility are limited by the hole- and electron-phonon short range interactions scattering above and below 315 K, respectively. An energy level of 35 meV and a set of donor energy levels located at 360, 280, 220 and 170/152 meV are determined from the temperature dependencies of the carrier concentration and conductivity. A hole, electron, hole-electron pair effective masses of 0.24 in,, 0.14 m(o) and 0.09 m(o) and hole- and electron-phonon coupling constants of 0.50 and 0.64, respectively, are obtained from the Hall effect measurements. The theoretical fit of the Hall coefficient reveals a hole to electron mobility ratio of 0.8. (C) 2004 WILEY-VCH Verlag Gmbh & Co. KGaA, Weinheim.Article Growth and Characterization of Tl3inse4< Single Crystals(Elsevier Sci Ltd, 2011) Qasrawi, A. F.; Gasanly, N. M.Tl3InSe4 single crystal has been successfully prepared by the Bridgman crystal growth technique. The crystal that is reported for the first time is found to be of tetragonal structure with lattice parameters of a=0.8035 and c=0.6883 nm. The electrical resistivity and Hall effect measurements on the crystal revealed a conductivity type conversion from p- to n-type at a critical temperature of 283 K. The electron to hole mobility ratio is found to be 1.10. The analysis of the temperature-dependent electrical resistivity, Hall coefficient and carrier concentration data reveals the extrinsic type of conduction with donor impurity levels that behave as acceptor levels when are empty. The data analysis allowed the calculation of the hole and the electron effective masses as 0.654m(0) and 0.119m(0), respectively. In addition, the temperature-dependent Hall mobility in the n-region is found to be limited by the electron-phonon short-range interactions scattering with an electron-phonon coupling constant of 0.21. (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 26Citation - Scopus: 26Etectron-Phonon Short-Range Interactions Mobility and P- To N-Type Conversion in Tlgas2 Crystal(Wiley-v C H verlag Gmbh, 2006) Qasrawi, AF; Gasanly, NMThe conductivity type conversion from p- to n-type at a critical temperature of 315 K in TlGaS2 crystals is observed through the Hall effect measurements in the temperature range of 200-350 K. The analysis of the temperature-dependent electrical resistivity, Hall coefficient and carrier concentration data reveals the extrinsic type of conduction with donor impurity levels that behave as acceptor levels when are empty. The data analysis allowed the calculation of hole and electron effective masses of 0.36m(0) and 0.23m(0), respectively. In addition, the temperature-dependent Hall mobility is found to decrease with temperature following a logarithmic slope of similar to 1.6. The Hall mobility in the n-region is limited by the electron-phonon short-range interactions scattering with an electron-phonon coupling constant of 0.21. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
