In-plane flux pinning in melt-textured YBa2Cu3O7-Y2BaCuO5 composites

The critical currents of a series of YBa2Cu3O7/Y2BaCuO5 (123-211) melt-text ured ceramic composites have been measured inductively with the field appli ed parallel to the nb planes (H parallel to ab) and compared to those previ ously analyzed when H parallel to c. In-plane vortex pinning mechanisms are analyzed from temperature and field dependence of J(c)(c)(H parallel to ab ) in samples with different concentration of 211 particles. A hierarchy of pinning centers has been identified and analyzed: 123/211 interfaces, dislo cations, stacking faults, and twin boundaries. We show that the interface o f the secondary phase Y2BaCuO5 with the superconducting matrix plays an imp ortant role in pinning the Josephson vortices though with a reduced efficie ncy as compared to Abrikosov vortices. In addition, we identify a second co ntribution to flux pinning which is independent of V/d, i.e., the amount of interface between the Y2BaCuO5 particles and the matrix, that we associate with in-plane linear defects, such as dislocations and partial dislocation s surrounding the stacking faults. Finally, the contribution to the pinning of Josephson vortices from twin planes has also been evaluated. [S0163-182 9(98)03446-8].