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Öğe Effect Y substitution on the microstructure, transport and magnetic proprieties of Bi2Sr2Ca1Cu2O8+? superconducting ceramics(Walter de Gruyter GmbH, 2016) Menassel, S.; Mosbah, M.-F.; Boudjadja, Y.; Altintas, S.P.; Varilci, A.; Terzioglu, C.In high Tc superconductors (HTSC) the activation energy gives information about the pinning properties of a sample under applied magnetic field. Pinning of vortices determines the critical current density Jc which is of great importance for practical applications of HTSC. Instead of magnetic measurements, the activation energy may be calculated from resistivity measurements realized under magnetic field. This kind of measurement has been made in this work for yttrium doped samples of Bi2Sr2CaCu2O8+d (Bi-2212) for different values of applied magnetic field. Samples of Bi2Sr2Ca1-xYxCu2O8+d (x = 0, 0.025, 0.1, 0.25) were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray. The measurements of resistivity were made using a classical four probe method and DC current. The magnetic field was applied with a constant amplitude of 0 T, 1 T, 2 T and 3 T. The obtained results show that the activation energy decreases with introduction of yttrium, but has a relative maximum when x is equal 0.1. The decrease of the activation energy is explained by the granular nature of the samples which promotes 3D transition to 2D of the vortex lattice. © 2016 Wroclaw University of Technology.Öğe Investigation of Cr addition effect on structural, morphological, electrical and magnetic properties of Bi(Pb)-2212 superconductors(Springer, 2023) Menassel, S.; Galluzzi, A.; Boudjadja, Y.; Altıntaş, Sevgi Polat; Terzioğlu, Cabir; Polichetti, M.The main purpose of this research work will assess the effect of Cr addition on the properties of Bi1.8Pb0.4Sr2CaCu2O8+d superconducting ceramics. The samples are produced from industrial powders with different amounts of Cr (0, 1, 2, 3, 4, 5, 6 and 7 wt %) by sol-gel synthesis route. The influence of doping element has been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrical resistivity and magnetic characterizations. In particular, the eventual presence of secondary phases as a result of Cr doping on the undoped sample was investigated by using XRD. By means of SEM analysis, the Cr doping influence on the grain morphology of the samples was explored. Contrarily, the T-c,T-on and the T-c,T-off of the samples have been obtained by using electrical resistivity measurements and their behavior as a function of the Cr doping has been discussed. Finally, by performing magnetization analysis versus temperature and magnetic field, the behavior of the critical temperature T-c and of the critical current density J(c) as a proportion of the Cr concentration has been discussed.Öğe Microstructural and magneto-transport properties of Bi1.6Pb0.4Sr2Ca1-xGdxCu2O8+delta superconducting ceramics(Elsevier, 2017) Boudjadja, Yazid; Amira, Abderrezak; Mahamdioua, Nabil; Saoudel, A.; Menassel, S.; Varilci, Ahmet; Terzioglu, Cabir; Altıntaş, Sevgi PolatThis study aims to investigate the effect of Gd doping on the phase formation, microstructure, transport and magnetic properties of the Bi(Pb)-2212 system. A series of superconducting bulks with a nominal composition of Bi1.6Pb0.4Sr2Ca1-xGdxCu2O8+delta with x= 0, 0.05, 0.10 and 0.15 are synthesized by the solid state synthesis route. The formed samples are characterized by means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), electrical transport and magnetic measurements. The experiment results reveal that all the samples doped are composed of Bi-2212 phase and traces of Bi-2201 secondary phase when compared to the undoped sample. The refinement of cell parameters shows that the doping reduces the cell volume of the samples. The texture degree decreases with doping while the degree of orthorhombicity increases. Quantitative EDS analysis confirms that Gd atoms are successfully introduced into crystalline structure. The SEM micrographs show randomly distributed grains with a flake-like shape. The highest value of onset critical transition temperatures is obtained for x= 0.10 and is about 90.22 K, which correlates well with the observed slope of resistivity and the hole concentration of the CuO2 layers. Magnetic hysteresis loops suggest that the diamagnetism, remanant magnetization and lower critical field are better for x= 0.10. Based on the enhancements of both grain boundary weak-links and flux pinning centers, improvement of the critical current densities and flux pinning density is obtained with this kind of doping.Öğe Synthesis of BiSrCa(Y)CuO superconductor from the Sol-Gel method and the effect of Y substitution(Amer Inst Physics, 2012) Menassel, S.; Mosbah, M-F; Altıntaş, Sevgi Polat; Varilci, Ahmet; Bouaicha, F.Superconducting Bi(2)Sr(2)Ca(1-x)YxCu(2)O(8) ceramics samples have been prepared by Sol-Gel methods using citrate process. The influences of the conditions of preparation of oxide powder compound on structural and superconducting properties have been investigated by X ray diffraction (XRD), Scanning Electron Microscopy (SEM) equipped with EDS. The critical transition temperatures T-c have been determined by resistivity versus temperature measurements. Cell parameters samples were calculated from XRD patterns. The polyacryl amide gel makes the citrate process easier, more rapid and affords the possibility of synthesis of high quality oxide powders.
