Effect of magnetic field and gamma irradiation on the electrical properties and structure of the Tl-based ceramic superconductors

Ozkan, H
Hasanlı, Nızamı
Kayed, T
The voltage-current (V-I) characteristics, critical temperatures and the critical currents of Tl2Ba2CaCu2O8 (Tl-2212) and Tl2Ba2Ca2Cu3O10 (Tl-2223) ceramic superconductors were studied in magnetic fields up to 80 mT after several gamma irradiations up to 100 MR. The effect of gamma irradiation on the structure of these materials has also been studied. The normal state resistance increases by 20-30% with gamma irradiation, most of the changes taking place in low gamma doses up to 10 MR. The critical temperatures of Tl-2212 and Tl-2223 decrease by about 8 K up to 30 MR and approach the saturation values of 101 K and 113 K, respectively, with further increase of gamma dose. For Tl-2212 in the 96-98 K temperature range the V-I behaviours become nearly ohmic under a gamma dose of about 30 MR or in an external magnetic field of 20-30 mT. In the same temperature range the critical current decreases rapidly in low gamma doses up to 10-25 MR; above that it decreases only slightly. For both materials, the positions and widths of the x-ray diffraction peaks almost remain the same but the peak intensities decrease by 10-40% with gamma irradiation, the rate of decrease being higher in the 0-30 MR range. These observations indicate that drastic changes in the lattice do not take place with gamma irradiation but substantial electronic excitations and point defects may be generated, at higher rate in low gamma doses, to affect the concentration and arrangements of the carriers and the links between the grains.


Effect of lithium doping on the properties of Tl-based superconductors
Kayed, TS; Ozkan, H; Hasanlı, Nızamı (IOP Publishing, 2001-09-01)
The effects of lithium doping on the formation and properties of the T1-based superconductors have been studied. Lithium atoms up to around 3 mol.% have been added to the oxides of nominal composition Tl1.8Ba2Ca2.2Cu3Ox, and the usual solid-state reaction method has been applied. Lithium additions in the range 0.23-0.29 mol.% increase the fraction of the Tl-2223 phase and significantly improve the critical temperature of the samples. Higher amounts of lithium additions diminish the Tl-2223 phase, reduce the...
Voltage-current characteristics of the thallium-based ceramic superconductors
Ozkan, H; Topal, U; Hasanlı, Nızamı; Albiss, B; Kayed, T (IOP Publishing, 1999-09-01)
Voltage-current (V-I) characteristics of the ceramic Tl2Ba2CaCu2O8 (Tl-2212) and Tl2Ba2Ca2Cu3O10 (Tl-2223) superconductors were studied in magnetic fields up to 80 mT at different temperatures just below the critical temperature. The V-I data were fitted to a power law expression V = I-beta(T,I-B) in which the exponential parameter beta is found to decrease rapidly with increase of temperature and magnetic field. In zero magnetic field the slopes of beta versus T graphs change drastically in a narrow temper...
Critical currents in Bi-2223 tapes near T-c under magnetic field and gamma-irradiation
Kayed, TS; Ozkan, H; Hasanlı, Nızamı; Ercan, I (IOP Publishing, 2000-12-01)
The critical temperature and critical current of Bi-2223 tapes have been studied near T-c under a magnetic field and gamma -irradiation. T-c decreases from 109 to 96 K with an increase in B up to 100 mT. In the 100-110 K range I-c decreases by about 75-85% at steady rates in low fields up to 20-50 mT, then decreases to zero at slower rates with further increase of field. The I-c versus B plots are non-exponential in small fields (up to 30 mT at 100 K and up to 10 mT at 108 K) and change to exponential form ...
Effect of cooling rate on microstructure and high temperature stability of rapidly solidified Al-Fe-V-Si alloys
Kalkanlı, Ali (Informa UK Limited, 1999-01-01)
Recently, AI-Fe-V-Si alloys have received more attention owing to their high temperature stability associated with vanadium rich precipitates and silicides. In this work, a series of alloys was prepared and processed by melt spinning and gas atomisation to observe the effect of solidification rate on crystal structures existing in both as cast and heat treated conditions. This study covers their microstructural examination and crystallography. The composition of these alloys was Al-(6.8-7.8)Fe-( 1.0-3)V-(1....
Enhancement in the high-T-c phase of BSCCO superconductors by Nb addition
Sozeri, Huseyin; Ghazanfari, Nader; Ozkan, Husnu; Kilic, Ahmet (IOP Publishing, 2007-06-01)
Pure and Nb2O5 added Bi1.6Pb0.4Nbx Sr2Ca2Cu3O delta superconductors ( x varies up to 0.30) were synthesized by the solid state reaction method. Structural and superconducting properties of the samples were investigated. The fraction of the high-T-c phase ( 2223) increases with Nb addition up to x = 0.10, for which a nearly single 2223 phase was obtained. The critical temperature of the samples increases from 96 to 104 K with doping up to x = 0.20 and a further increase in Nb decreases the Tc sharply. Simila...
Citation Formats
H. Ozkan, N. Hasanlı, and T. Kayed, “Effect of magnetic field and gamma irradiation on the electrical properties and structure of the Tl-based ceramic superconductors,” SUPERCONDUCTOR SCIENCE & TECHNOLOGY, pp. 161–164, 2000, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/46276.