STRUCTURAL AND SUPERCONDUCTING PROPERTIES OF Bi4Sr3Ca3CuyOw AND Bi4Sr3Ca3Cu4−xMxOz(M=Fe, Cr AND Mn) GLASS CERAMICS

Abstract

The synthesis of glass ceramic superconductors of Bi 4 Sr 3 Ca 3 Cu y O w(3≤y≤6) and Bi 4 Sr 3 Ca 3 Cu 4−x M x O z ( M=Fe , Cr , Mn and 0≤x≤0.2) compositions is reported. The 4334 sample is found to be the optimum composition to obtain Bi-2212 superconducting phase. X ray diffraction studies indicate that the solid solubility of 3d metal ions in the 4334 system is limited to x=0.05 in the case of Fe and Cr and x=0.1 in the case of Mn. A systematic decrease in Tc with increasing dopant concentration is observed from resistivity as well as AC susceptibility measurements. Tc depression rates, however, are found to differ for different dopants. XRD studies indicate the decrease in c lattice parameter with increase in dopant content. The systematics of the superconducting transition is discussed in view of Tc depression rates.