Microstructural and magneto-transport properties of Bi_1.6Pb_0.4Sr₂Ca_1−xGd_xCu₂O_8+δ superconducting ceramics

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• 作者：Y. Boudjadja^a ; ^{yazid.bouj@Gmail.com} ; A. Amira^a ; N. Mahamdioua^a ; A. Saoudel^a ; S. Menassel^b ; A. Varilci^c ; C. Terzioglu^c ; S.P. Altintas^c
• 关键词：Bi-2212 ; HTSC ; Critical current density ; Hysteresis loops ; Flux pinning
• 刊名：Physica B: Condensed Matter
• 出版年：2017
• 出版时间：15 January 2017
• 年：2017
• 卷：505
• 期：Complete
• 页码：68-73
• 全文大小：1404 K
• 卷排序：505

文摘

This 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+δ 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.