Critical Current Density in Polycrystalline High-Tc Superconductors with Disordered Tilt Boundaries

A theoretical model is suggested which describes the effect of tilt boundaries with chaotically arranged dislocations on the critical current density in high-transition-temperature (Tc ) superconductors. Stress fields of such boundaries, that suppress high-Tc superconductivity, are revealed to be long-range as compared to those of tilt boundaries with periodically ordered grain boundary dislocations. With this factor taken into consideration, the dependence of the critical current density accross tilt boundaries on boundary misorientation θ is calculated and compared with the experimental data.