Abstract
Dislocations in oxide superconductors YBa2Cu3O7−x and Bi(Pb)-Sr-Ca-Cu-O have been studied by high voltage electron microscopy. In the analysis, it was assumed that c-axis component of the Burgers vector is zero, because both materials have a layered structure. In YBCO, only one type of dislocation (b=a⟨1,0,0⟩) was observed. The population of the defect, however, is low in a sintered specimen. Twin boundary may act as a pinning center of the superconducting fluxoid. In BSCCO, two types of dislocations (b=a⁄2⟨110⟩ and a⟨100⟩) were found. Dislocation network can be formed by the combination of them. Most of high density of dislocation are grown-in defects and, therefore, they must be related to a critical current property. In order to explain the existence of dislocations with large Burgers vector b=a⟨100⟩, a model with ‘decomposition of partial dislocation in Bi2O2 layer’ is proposed.
