Evidence for weak link and anisotropy limitations on the transport critical current in bulk polycrystalline Y1Ba2Cu3Ox

摘要: Measurements of the transport critical‐current density (Jc), magnetization Jc, and magnetoresistance in a number bulk sintered samples Y1Ba2Cu3Ox from several different laboratories indicate that Jc is limited by weak‐link regions between high regions. The has Josephson character, decreasing two orders magnitude as magnetic field increased 0.1 to 10 mT at 77 K. An examination grain‐boundary region shows no observable impurities or second phases scale [001] lattice planes (∼12 A). effect intrinsic conduction anisotropy discussed. A current‐transfer model proposed which weak along c axis plays role limiting grain boundaries. Orienting grains powder state during processing may result enhanced conductors.