Evidence of Enhanced Flux Pinning by Dislocations in Deformed Textured Y₁Ba₂Cu₃O_xSuperconductor

Abstract

As-melt and uniaxially deformed melt textured YBCO (123) superconductors have been used to examine the role of dislocations in flux pinning. These superconductors were subjected to a high temperature annealing process. After annealing, the critical current densities (J c) of both as-melt and deformed superconductors are found to have decreased dramatically both in zero field as well as in an applied field of 1.5 T. Furthermore, the distinct characteristic of deformed superconductors, i.e., J c ( H|| c-axis)≈J c ( H|| a-b), has totally disappeared after annealing the samples at 900° C for 48 h in flowing oxygen. Transmission electron microscopy revealed that the high dislocation density normally observed in deformed 123 superconductors has been significantly reduced. In addition, several other microstructural changes were also investigated. These results indicate that the large amount of dislocations generated during the deformation process are effective flux pinning centers in these superconductors. Meanwhile, it is suggested that pinning by stacking faults is magnetically sensitive where the effect is maximum at low fields.

Tailoring of microstructure and critical currents in directionally solidified

“…Stacking faults (SFs) constitute a prominent defect in melttextured 123 materials, which have been the subject of intense debate regarding both their generation mechanism and implications on superconducting properties [8,[54][55][56][57][58][59][60]. The most widely observed SF in 123 materials consists of a double CuO x chain layer [61] causing a local depression of the superconducting order parameter.…”

Neodymium as a dopant in top-seeding-melt-texture-growth-processed YBa2Cu3O7−δceramics

“…Most of workers do believe that defects in the superconducting material can pin the vortices and thus lead to improved superconducting properties. Most of the defects present in Y123 samples have been studied in order to understand their influence on the superconducting properties (see, for example, Daeumling et al [14] for oxygen vacancies, Zhang et al [15] for dislocations, Murakami [16] for stacking faults or Kes et al [17] for twin boundaries). Unfortunately, it is very difficult to obtain clear experimental evidence of the influence of one of these kinds of defects on the superconducting properties as it is very difficult to obtain samples presenting only one varying defect parameter.…”

Stability and evolution of stacking faults in melt textured YBa2Cu3O7−x

“…[1][2][3][4][5][6][7] The most widely observed SF in 1-2-3 consists of a double CuO x chain layer 8 causing a local depression of the superconducting order parameter. [1][2][3][4][5][6][7] The most widely observed SF in 1-2-3 consists of a double CuO x chain layer 8 causing a local depression of the superconducting order parameter.…”