Title :
Growth of CaO precipitates in superconducting Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+ delta /
Author :
Xu, M. ; Polonka, J. ; Goldman, A.I. ; Finnemore, D.K. ; McKernan, S.
Author_Institution :
Ames Lab., Iowa State Univ., IA, USA
fDate :
3/1/1993 12:00:00 AM
Abstract :
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.<>
Keywords :
X-ray diffraction examination of materials; bismuth compounds; calcium compounds; crystal growth from melt; crystallisation; high-temperature superconductors; magnetisation; precipitation; scanning electron microscope examination of materials; strontium compounds; Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+ delta /; CaO precipitates growth; O/sub 2/ partial pressure; X-ray powder patterns; crystallisation; diagnostic tools; environmental scanning electron microscopy; fine dispersion; magnetisation; melting; oriented grains; superconductor; Bismuth; Crystallization; Electric variables control; High temperature superconductors; Position sensitive particle detectors; Scanning electron microscopy; Strontium; Superconducting filaments and wires; Superconducting materials; X-ray detection;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
