Structural and superconducting properties of Bi1.7Pb0.4Sr2−xGdxCa1.1Cu2.1Oy system

• Published in: Physica. C, Superconductivity Vol. 449; no. 2; pp. 109 - 115
• Main Authors: Biju, A., Abhilash Kumar, R.G., Aloysius, R.P., Syamaprasad, U.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2006; Elsevier Science
• Subjects: (Bi, Pb)-2212 superconductor; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical current density (JC); Critical currents; Critical temperature (TC); Effects of crystal defects, doping and substitution; Exact sciences and technology; Gd substitution; Physics; Properties of type I and type II superconductors; Superconductivity; Transition temperature variations; Critical temperature (TC); (Bi,Pb)-2212 superconductor; Gd substitution; Critical current density (JC); 74.72.Hs; Critical current density; Critical temperature (Tc); Metal-insulator transition; Superconducting transitions; Superconductivity; Polycrystals; Bismuth oxides; Lead oxides; XRD; Phase analysis; Critical current density (Jc); Gadolinium oxides; Calcium oxides; Strontium oxides; Synthesis; High-Tc superconductors; Chemical composition; Copper oxides
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2006.07.006

The effect of substitution of the rare earth ion Gd at Sr site of (Bi,Pb)-2212 superconductor has been studied by varying Gd in the stoichiometric level. The samples were prepared by solid-state synthesis route in the polycrystalline bulk form. Phase analyses of the samples by XRD, microstructural examination by SEM, elemental analysis by EDAX and measurements of electrical and superconducting properties have been carried out to assess the effects of substitution. Both the critical temperature (TC) and critical current density (JC) are found to increase with Gd substitution at Sr site and the maximum TC was observed for x=0.3 in the initial composition Bi1.7Pb0.4Sr2−xGdxCa1.1Cu2.1Oy and the maximum JC for x=0.2. The increase in TC and JC is explained due to the substitution of Gd3+ in place of Sr2+ and consequent change in chemical and electronic inhomogenities. Above these level TC and JC begin to reduce and a metal–insulator (MI) transition occurs at higher doping levels (x>0.5).