Improvement of critical parameters of YBa2Cu3O6.9 by low temperature treatment in the presence of water vapors

摘要

The effect of double thermal treatment at temperatures of 200 degrees C and 930 degrees C on the critical parameters of highly textured YBa2Cu3O6.9 ceramics has been examined. It has been shown that particles non-superconducting at T = 77 K, as well as planar stacking faults formed. at low-temperature treatment in a humid atmosphere, are pinning centers of magnetic vortices. After recovery annealing (at 930 degrees C), the planar faults are partially preserved and serve as effective pinning centers in a magnetic field perpendicular to the c-axis. In addition, optimal double-annealing conditions have been found to significantly increase the critical current density up to the values j(c) >= 10(4) A/cm(2) in the external magnetic field (10 T), applied perpendicular to the c-axis. (C) 2015 Elsevier Ltd. All rights reserved.