Effect of Different Calcination Process and Gd 2 O 3 as Impurities on the Different Phases of Bi-Based Superconductor

Abstract

In this research two samples of a nominal composition Bi1.6Pb0.4Sr2Ca2Cu3Ox were prepared by the solid state reaction method, using two different routes. Codes A and B are used to refer to the two samples. In preparing sample A, the standard method for calcination was used, while for sample B, the SrCO3 and CaCO3 were calcinated at 1100˚C for 3 h. Calcination was done separately on SrCO3 and CaCO3 in order to eliminate CO2. Then after mixing and grinding, the powder mixtures of Bi2O3, CuO, PbO, SrO and CaO were calcinated at 840˚C for 70 h. Also, the samples (samples C) of nominal compositions Bi1.6Pb0.4Sr2Ca2Cu3Ox + % x Gd2O3 (% x = 0, 3, 5, 7 and 9) have been synthesized by this method. The XRD and SEM results show that addition of Gd2O3 helps to increase the amount of Bi-2212 phase, while alternative calcination process improves the formation of the Bi-2223 phase. In addition, the AC susceptibility measurements confirm the XRD and SEM results.