Annealing temperature dependence of the 2223 phase volume fraction in the Bi–Sr–Ca–Cu–O system

Abstract

We have developed a reliable method based on AC magnetic susceptibility measurements to determine the Bi 2 Sr 2 Ca 2 Cu 3 O 10x (2223) phase volume fraction and the average grain radius in multiphasic polycrystalline Bi±Sr±Ca± Cu±O samples. Precision and applicability of the method are discussed and compared with those of the XRD peak integration procedure. The method is used to investigate the in¯uence of the annealing temperature on the synthesis of the 2223 phase in air. The results show that, for a 120 h annealing time, T 849°C is the most favourable among the investigated temperatures. Evidence is also given that higher temperatures promote the decomposition of the 2223 phase into the Bi 2 Sr 2 CaCu 2 O 8x (2212) phase and impurities. Ó

Higher critical current density achieved in Bi-2223 High-Tc superconductors

“…The observed peak intensities have been weighted by taking the relative intensities in the pure compounds given by the JCPDS-ICDD diffraction cards (Manfredotti et al, 2001). The choice of the best fitted card was difficult due to peak overlap between the High T c -phase (Bi-2223) and Low T c -phase (Bi-2212).In order to estimate the volume fraction, fi, of certain phase i, XRD peak intensities have to be weighted taking the relative intensities of the peaks in the pure compounds given by the XRD files.…”

“…The choice of the best fitted card was difficult due to peak overlap between the High T c -phase (Bi-2223) and Low T c -phase (Bi-2212).In order to estimate the volume fraction, fi, of certain phase i, XRD peak intensities have to be weighted taking the relative intensities of the peaks in the pure compounds given by the XRD files. The conversion factor, K, between the two scales is the ratio of the experimental observed intensity, Ip, to that of some standard reference diffraction lines, It, given in JCPDS-ICDD cards and is expressed according to Manfredotti et al (2001) as:…”

The Effect of Precursor Powder Size on the Microstructure and Intergranular Properties of (Bi,Pb)2Sr2Ca2Cu3Oy Superconductors

“…The Bi-2212 phase is known to be thermodynamically stable over an almost wide temperature range and in the presence of most of the compounds existing in this system. 5) On the other hand, the Bi-2223 phase is only stable within a narrow temperature range and exhibits phase equilibrium with only a few of the compounds existing in the system. 6) It seems that two major issues complicate the development of the Bi-2223 phase, first is its stability in a very narrow temperature range and second is the kinetics of its formation are so slow that, it is almost impossible to obtain the pure Bi-2223 phase material.…”