Critical current densities of high-T-c superconductors (Cu,Cr)Sr2Can-1CunO2n+3 (n=2,3) prepared under high pressure

Critical current densities (J(c)) and irreversibility fields (B-irr) of hig h-T-c superconductors (Cu,Cr)Sr2Can-1CunO2n+3 (n = 2, 3) prepared under hig h pressure were determined from the hysteresis in DC magnetization loop. Th ey show higher J(c) values than other high-T-c superconductors such as YBa2 Cu3O7, Bi-phases, Hg-phases, (Cu,C)-based phases, etc. for the almost entir e range of temperature below T-c. Their B-irr values are also very high; at 77 K, for instance, B-irr of (Cu, Cr)-1223 was over 5 T. In addition to th e polycrystalline bulk samples, magnetically grain aligned samples of the ( Cu, Cr)-phases were investigated to discuss superconductivity anisotropy. T he good J(c)-related properties of the (Cu, Cr)-phases seem to be caused by their less anisotropic electronic structures and sufficient number of effe ctive pinning centers due to the random arrangement of Cu and Cr in the blo cking layer. (C) 1999 Published by Elsevier Science B.V. All rights reserve d.