An XRD Study of the Phase Equilibria of (Bi2−xPbx)Sr2Ca2Cu3O10−δ/Ag Tapes at the Ceramic-Silver Interface in the Temperature Range 810 to 846°C

Abstract

The formation kinetics of (Biz-zPb,)Sr?CazCu,Ol~-d in a monecored silver-sheathed tape in air and at thermodynamically-stable temperatures has been investigated using X-ray diffraction. The effect of changing the processing time and temperature on a single composition, B i~.~P~.~S r~.~C~.~~C u~.~O~~-~ WM observed. The products were found to be multi-phase (in contrast to the powder alone) and a possible reaction mechanism is discussed and compared to data obtained by other workers.') Technology Centre, Wrexham, Clwyd LL13 9XP, United Kingdom.

The formation mechanism and the development of grain texture in the preparation of Ag-sheathed Bi-2223 superconducting tapes

“…Two models for the 2223 formation mechanism, intercalation and nucleation and growth, suggest different dependences of the resultant 2223 grain texture on the precursor 2212 texture [5,9,10]. There is experimental evidence supporting all these mechanisms, and there is still controversy over which is the correct model, or whether both processes occur simultaneously [11][12][13][14][15][16][17]. Intercalation suggests that the 2212 grains serve as a grain-by-grain template for 2223 formation, and thus the grain texture before and after reaction should be similar.…”

Enhancement of the critical current density of Ag-sheathed Bi-2223 tapes by optimized intermediate rolling

“…Since the volume fraction of unreacted 2212 in the tape is related to the ability of microcracks to heal, it can be used as a good guide to estimate the optimum intermediate rolling reduction. Furthermore, it may also be concluded that the optimum intermediate rolling reduction is also dependent on the initial sintering temperature and time, because it has been well recognized that the 2212 volume fraction is controlled by these variables [8].…”

“…Moreover, if the performance of different precursor powders is to be compared, the intermediate rolling reduction should be one of the optimization parameters, since different precursor powders may have different reaction kinetics. Filamentary thickness is another factor which may also affect the optimum intermediate rolling reduction, as the Ag/BSCCO interface affects the formation of the Bi-2223 phase significantly [8,9]. Optimized sintering conditions in monofilamentary tapes, which have the lowest Ag/BSCCO interface ratio, may not be the same in multifilamentary tapes.…”

Manufacture of high critical current multifilamentary tapes using the wire-in-tube technique

“…The highest J C values have had aligned microstructures [6] and recent studies have shown that a disproportionate amount of the current distribution is concentrated at the silver-ceramic interface [7]. Kinetic studies have also shown that the formation of (Bi 2−x Pb x )Sr 2 Ca 2 Cu 3 O 10−δ at the silver interface takes place via a rapid intercalation mechanism [8].…”