Growth of CaO precipitates in superconducting Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+ delta /

Crystallization studies of Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+ delta / have been undertaken in order to explore the possibility of growing large oriented grains of this superconductor so that they contain a fine dispersion of tiny CaO precipitates. At low oxygen partial pressure, CaO forms preferentially over the alkaline earth cuprates and it is found to be the dominant precipitate when there is excess Ca. Hot stage environmental electron microscopy and in-situ high temperature X-ray studies have been used as the primary diagnostic tools to determine the best conditions for the growth of this fine dispersion. Because CaO is cubic, it forms equiaxed precipitates with diameters in the range of 1 to 3 mu m.<
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