Synthesis and characterization of glass-ceramic Bi_2-<i>x</i>Ga_<i>x</i>Sr₂Ca₂Cu₃O_10+<i>y</i>superconductors

Abstract

We have melt quenched a series of Ga substituted Bi2-xGaxSr2Ca2Cu3O10+y samples with the compositions with x = 0.2, 0.4, 0.6, 0.8 and 1.0. Microstructure, thermal properties including crystallization activation energy, magnetic and superconducting properties were investigated. We have found that Ga3+ ions have a solid solubility limit in the BSCCO system and this limit was passed at x = 0.6. Below this limit HTc BSCCO n = 3 phase was obtained, but after the solid solubility limit samples yield multiphase superconducting properties. Extended heat treatment at 840°C displayed no suppression of the solid solubility limit. The crystallization kinetic studies were investigated using non-isothermal kinetic models of Kissinger and Augis-Bennet. Higher crystallization activation energies, Ea, were obtained compared to unsubstituted BSCCO materials, glassification improved and glass handling time increased. The substitution had a slight effect on Jc, the flux pinning in the material was improved and better Jc values were obtained below the solid solubility limit.