Influence of water vapor on the formation of pinning centers in YBa2Cu3Oy upon low-temperature annealing

• Published in: Physics of metals and metallography 2017-08, Vol.118 (8), p.738-748
• Main Authors: Bobylev, I. B., Gerasimov, E. G., Zyuzeva, N. A.
• Format: Article
• Language: English
• Subjects: Carrying capacity; Ceramics; Chemistry and Materials Science; Copper; Critical temperature; Crystal defects; Current density; Defect annealing; Electrical and Magnetic Properties; Faults; Heat treatment; Low temperature; Magnetic fields; Materials Science; Metallic Materials; Oxygen content; Reduction; Superconductivity; Water vapor
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X17080038

The influence of the double heat treatment ( T = 300 and 930°С) on the critical parameters of highly textured YBa 2 Cu 3 O 6.96 and YBa 2 Cu 3 O 6.8 ceramics has been investigated. It has been shown that, upon low-temperature annealing in humid air, planar stacking faults are formed in these ceramics. These defects are partly retained after reduction annealing (at T = 930°С) and are efficient pinning centers in magnetic fields applied parallel and perpendicular to the c axis. Due to the absorption of water, the oxygen content is increased in the ceramics, which is accompanied by an increase in the critical temperature of superconducting transition up to 94 K for YBa 2 Cu 3 O 6.96 and up to 90 K for YBa 2 Cu 3 O 6.8 . Optimal conditions of the double annealing have been established, after which the critical-current density increased to j c ≥ 10 4 А/сm 2 in an external magnetic field of up to 6 T. The low-temperature treatment in the neutral atmosphere saturated by water vapors deteriorates the current-carrying capacity of the highly textured ceramics, which is connected with the disappearance of texture due to the copper reduction and the precipitation of impurity phases.