Different types of dislocations in YBa2Cu3O7- delta.

Abstract

In the present study, dense pellets of polycrystalline YBa2Cu3O7-delta were made by dynamic powder compaction. The shock wave, which passes through the initially loose powder, generates multiple defects. Its hydrostatic component suppresses the brittle nature of YBa2Cu3O7-delta, and so plastic deformation such as dislocation generation and glide is expected. This paper reports on the characterization of structure defects observed in shock loaded samples, compacted at E/M ratios ranging from 0.8 to 2.3. The microstructure of shock compacted samples is compared to that of the initial, noncompacted powders. Apart from the well-established [100](001) glide system, two additional glide systems have been identified: [110](110BAR) and [010](100). They are characterized both by diffraction contrast and high-resolution transmission-electron-microscopy techniques. The interaction between the different types of dislocations and other structure defects, as well as their role in cleavage and stacking fault generation is investigated. Finally, the possible role in flux pinning of the dislocation types is briefly discussed.