MICROSTRUCTURES OF HIGH-J(C) MELT-TEXTURED YBA2CU3O7-X/AG SUPERCONDUCTORS

Silver has been previously added to the melt-textured YBa2Cu3O7-x in order to increase the critical current density (J(c)) of these materials. However, the effect of this addition on the J(c) is presently unclear. The purpose of this study is to investigate the effect of silver on both critical current density and the microstructure of the melt-textured YBa2Cu3O7-x superconductors by means of X-ray diffraction, optical polarized microscopy, and transmission electron microscopy (TEM). The J(c) of the MTG YBCO/Ag samples is more than 10(4) A/cm(2) under the 5 kOe magnetic field. It has been shown that as the concentration of silver increases, the fraction of the 211 phase dispersed within the 123 matrix decreases. Therefore, the J(c) slightly decreases. These results, together with the effect of the 211 phase, dislocations, and other structure defects on flux pinning, are described in this paper.