Transport critical current in bulk sintered Y1Ba2Cu3Ox and possibilities for its enhancement

Several general processing methods for increasing the critical current density, Jc, in bulk sintered Y1Ba2Cu3Ox superconductor are outlined. Data indicate that the transport Jc in bulk polycrystalline specimens is dominated by a weak-link region between high-Jc grains and that potentially much higher Jc may be possible. Two possible causes of such a weak-link phenomenon are considered: low-Tc phases or impurities localized in the grain boundary region, and anisotropy of the superconducting properties. Several methods for minimizing the weak-link effects to increase the Jc are discussed