Crystallization of metal-oxide glasses in Bi-Sr-Ca-Cu-O systems

Bi-based high Tc superconducting fibers by melt extraction

“…This finding supports the model of Shi et 01. (Shi et al, 1989b) involving dift'usion of calcium and copper into 2212 grains to form the 2223 phase Bowever, the XRn results for our samples do not show the presence of CaJCuO, as was reported by tbis group.…”

“…Samples were annealed at temperatures between 1125 K and 1145 K, these being the optimal temperatures repoded in the literature (Shi et al, 1989b). No difFerence was found between \4amples…”

The effects of the post-annealing temperature on the growth mechanism of Bi2Sr2Ca1Cu2O8+ thin films produced on MgO (1 0 0) single crystal substrates by pulsed laser deposition (PLD)

“…The BSCCO system is one of the most studied members of the high-T C family of supercon ductors. Since Bi-2212 is more stable than Bi-2223, which can only be obtained within a very narrow temperature window [30][31][32], it is easy to produce Bi-2212 phase in thin film form. The thin films of the Bi-2212 phase can be synthesized with various methods , such as molecular beam epitaxy (MBE) [33,34], DC sputtering [35], RF sputtering [36], chemical vapor deposition (CVD) [37,38], and pulsed laser deposition (PLD) techniques [2,3,9,13].…”

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

“…As far as Ca 2 CuO 3 is concerned, its presence for annealing times not longer than 120 h has been reported only for temperatures equal to or greater than 850°C, but it can be observed also at the temperature of 840°C if the annealing time is prolonged to 240 h [3,4,13]. The reason for its presence in our samples could be twofold, in principle: on one hand, it could be interpreted as an incomplete synthesis of the 2223 phase by means of the reaction 1=2CuO Ca 2 CuO 3 2212 3 2223 [14]; on the other hand, it could result from the decomposition reaction 42223 3 42212 2Ca 2 CuO 3 Cu 2 O 1=2O 2 that can take place because of an insucient oxygen pressure [17,18].…”

“…There have been in the past a few attempts to draw phase or time±temperature±transformation Physica C 353 (2001) 184±194 www.elsevier.nl/locate/physc diagrams for the BSCCO system [3,4,11,13,14], but a major problem has often been the evaluation of the relative 2212 to 2223 phase contents, due to their intrinsic mixing. The typical method for such evaluation is based on the relative intensities of the corresponding X-ray diraction (XRD) peaks, but its precision is not very high, especially for very small phase contents.…”