Limits of the critical current density of polycrystalline high-temperature superconductors based on the current transport properties of single grain boundaries

A semiquantitative technique for estimating the limits of the critical current density in polycrystalline high-temperature superconductors is presented. This technique is based on the transport properties of single grain boundaries. Various factors essential in deducing the critical current density of polycrystalline high-Tc materials from the characteristics of single grain boundaries are discussed. The results for tectured, polycrystalline YBa2Cu3O7 fibers are reported, and the influence of the microstructure on their critical current density is discussed. © 1989 Springer-Verlag.