Influence Of Preparation TSIG Single Domain YBCO Bulks Performance SnO ₂ And MgO Doped

Enhanced the performance of the YBCO bulk superconductors is one of the most important work for its applications. Top-seeded infiltration and growth process(TSIG) is a very important and widely accepted method for the fabrication of the single domain YBCO bulk superconductors, in order to further improve its performance, effective flux pinning centers have to be introduced to improve the critical current density and the levitation force of the YBCO bulks. It is proved that second none superconducting phase inclusions can act as strong flux pinning centers in the YBCO bulks; and introduced by a low cost way.In this paper, YBCO bulk superconductors have been fabricated by TSIG process. Two types of none superconducting particles were introduced into YBCO bulks by doping it into the solid phase Y2BaCuO5(Y211). One is SnO2phase particles; the other one is MgO phase particles. YBCO bulk superconductors with doping different SnO2and MgO have been fabricated by TSIG process. The growth morphology, microstructure and levitation force of the samples have been observed and investigated.The levitation force measurement of the single-domain YBCO bulks with different SnO2indicate that the levitation force is increasing with the increasing of SnO2content, when x<0.7wt%; the levitation force of the samples decreases gradually when x>0.7wt%; when the SnO2content x=0.7wt%, the levitation force of the sample reaches the largest value36.ON. Through analysis of the microstructure of the samples, it is found that the average size of the Y211particles in the YBCO matrix is increasing first and then decreasing with increasing of SnO2addition, when the SnO2content x=0.7wt%, average size of Y211is of the smallest one(1.2μm). Therefore, the best doping content of SnO2in YBCO bulks is obtained at x=0.7wt%, this is in agreement with the result of the levitation force of the samples.The effect of MgO addition on the single domain YBCO bulk superconductors have also been investigated, including the growth morphology, microstructure and levitation force. Through analysis of the growth morphology of the bulks, it is found that the surface of the samples are of single domain morphology, but with an obvious "pyramidal" shape. The levitation force measurement of the samples with different amount of MgO addition indicate that the maximum levitation force is13.8N,16.6N and26.3N for the samples with different MgO addition of Owt%,0.05wt%and0.1wt%, the levitation force of the other samples with MgO addition higher than0.1wt%decreases rapidly. When the content of MgO is at1.0wt%, the levitation force of the bulk is almost zero. This is closely related with the substitution of Mg ions for Cu ions in the YBCO crystal and lead to a reduced critical temperature.