BSCCO 2212 growth synthesis by combustion

Abstract

Since the discovery of the Bi-Sr-Cu-O superconductor by Michel et al., many groups of scientists have pursued the search for higher and higher T_c's in the Bi-Sr-Ca-Cu-O system. At the initial stage, nearly all of the high T_c samples were prepared by the conventional solid-state reaction route using oxide or carbonate powders. However, the technique involves repetitive grinding, sintering, and cooling which takes around 72 to 300 hours. For this reason, many other methods for fabricating ceramic superconductors have been tried. The array of methods developed includes oxalate gel process, partial melting method, powder-in-tube method process, sol-gel method, and electrochemical technique. Many of these techniques require expensive equipment and elaborate procedures. In 1990, D. Rambabu reported a relatively simple and straightforward process called the combustion method where the precursors are in the nitrate form and allowed to combust with urea in an aqueous solution. This process has been reported to save a lot of time and energy. The combustion method, capable of providing highly homogeneous multi-component fine ceramic powders may be very attractive since it is well known that the compositional variation can dramatically affect the superconducting properties of the compounds. One problem, though, in the use of the nitrate form of the precursor materials is the introduction of many nitrate residues that cannot be eliminated by the combustion process alone. Thus, a postcombustion or denitration treatment was added.
The objective of the present work was to investigate the effect of the processing parameters (postcombustion temperature and sintering temperature) on the properties of Bi₂Sr₂CaCu₂O, particularly on the volume fraction of the 2212 phase in the samples, and to optimize the conditions for the synthesis of the high-T_c superconducting phase.