Preparation of Bi2Sr2CaCu2O8+δ(Bi2212) superconductor by Pechini sol–gel method: thermal decomposition and phase formation kinetics of the precursors

Abstract

Bi2212 high-temperature superconductors were prepared using Pechini sol–gel method, and the thermal decomposition process under air condition was obtained by synchronous thermal analyzer. The synthesis mechanisms of Bi2212 phase were determined by the combination of universal integral, differential and multi-rate scanning methods. The crystallization behavior, morphology, and superconductivity of the samples were characterized and analyzed by XRD, FESEM, PPMS, and SQUID, respectively. The results exhibited that the thermal decomposition reactions of the precursors were divided into three stages. The kinetics of Bi2212 synthesis reaction followed the mechanism mode of random nucleation and subsequent growth (n = 3) during the third stage which were used to guide the heat treatment of the final products. The average activation energy and the pre-finger factor of the synthesis reaction were 226 kJ/mol and 1.84 × 1011/min, respectively. Finally, the Bi2212 superconductor with high purity and acceptable performance with the Tc, onset of 77.1 K, Tc, zero of 63.5 K, and the Jc of 5.94 × 104 A/cm2, respectively, were prepared with shorter sintering time.