Grain Boundary Diffusion and Superconductivity in Bi-Pb-Sr-Ca-Cu-O Compound
The discovery  of high temperature oxide superconductors has caused tremendous excitement due to great technological importance. The critical current in polycrystalline oxide superconductors is low. Cava et al.  first measured critical current density, Jc in Y1Ba2Cu3O7 by transport method and reported Jc at 77K and zero magnetic field to be only 1100 A/cm2, compared to 105 A/cm2 reported  for epitaxial films. Moreover, the critical current in the polycrystalline material decreases drastically  at a low magnetic field. Similar low critical currents have also been observed  in polycrystalline Bi2CaSr2Cu2O8 and T12Ca2Ba2Cu3O10 compounds. Weak linking at the grain boundaries is thought  to be the cause for low Jc in polycrystalline high-Tc materials. By measuring Jc across single grain boundaries between  oriented grains of Y1Ba2Cu3O7, Mannhart et al.  have shown that high angle tilt grain boundaries behave like normal layers in SNS-type Josephson junctions.
KeywordsCritical Current Boundary Diffusion Auger Electron Critical Current Density Epitaxial Film
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