Softening of Bi2212 crystals and growth mechanism of Bi2212 and Bi2201 grown at the KCl flux surface
X L Wang; H K Liu; X Z Liao; S X Dou; X L Wang; Institute of Superconducting and Electronic Material, University of Wollongong, Wollongong, NSW 2522, Australia; H K Liu; Institute of Superconducting and Electronic Material, University of Wollongong, Wollongong, NSW 2522, Australia; X Z Liao; Institute of Superconducting and Electronic Material, University of Wollongong, Wollongong, NSW 2522, Australia; S X Dou; Institute of Superconducting and Electronic Material, University of Wollongong, Wollongong, NSW 2522, Australia
Журнал:
Superconductor Science and Technology
Дата:
1999-02-01
Аннотация:
A comparative study was carried out on observation of the growth mechanism of Bi2212 and Bi2201 crystals grown at the surface of a KCl flux by using optical microscopy and XRD. The growth of Bi2212 crystals is typically spiral mediated, while Bi2201 crystals are always layer-by-layer grown. We observed that the Bi2212 crystals grown on a KCl surface at are soft and can be bent freely. No softening was observed for the Bi2201 crystals. The generation of screw-dislocations can be caused by the coalescence of softened crystals. It is suggested that the formation of single, double and multiple spirals in the Bi2212 crystals can be explained by the softening of the Bi2212 crystals. TEM studies revealed abundant dislocation networks in the softened Bi2212 crystals.
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