<sub> 2. Gd <sub> 2 </ Sub> Ba <sub> 4 </ Sub> Cuwo <sub> X </ Sub> And Y </ Sub> The O <sub> 3 </ Sub> Doping On Tsig Preparation Of Single-domain Ybco Superconducting Bulk Properties Of The Imp

In order to improve the physical properties of single domain YBCO bulk superconductors fabricated by the top-seeded infiltration and growth process (TSIG), some defects acting as flux pinning centers have been introduced into the YBCO bulk superconductors. It is proved that the second phase inclusions can act as strong flux pinning centers in the YBCO superconductors, which can improve the physical property of samples.In this paper, two kinds of inorganic nanometer compounds as flux pinning centers in the YBCO superconductor. One is Gd2Ba4CuWOx (GdW2411) particle, the other is the composite of Gd2Ba4CuWOx and Y2O3 YBCO bulk superconductors with different dopant and dopant concentration have been fabricated by TSIG process. The surface morphology, microstructure and the levitation force of the YBCO bulk superconductors have been investigated.The XRD pure GdW2411 powder was prepared by solid-state reaction at temperature of 1080℃, with three times sintering and four times milling process.For GdW2411 doping YBCO bulk superconductors, it is discovered that nanoscale GdW2411 particles can be well introduced into YBCO bulk superconductors by TSIG process. The density of GdW2411 particles is gradually increasing with the increasing of GdW2411 additions, but the average size of the GdW2411 particles is nearly the same about 200nm, the size of Y211 particles is smaller than that of the TSMIG YBCO bulks, and they are tending to be self assembled and formed into a line at the growth steps of the YBCO crystal. In addition, the domain of YBCO bulk grown from the NdBCO seed can extand up to the whole samples when x<8wt%, but also random nucleations of YBCO grains arise when x>8wt%. The levitation force is increasing with the increasing of GdW2411 content, when x<4wt%, but decreasing with the increasing of GdW2411 additions when x>4wt%, the largest levitation is obtained at x=4wt%.For GdW2411 and Y2O3 doped YBCO bulk superconductors, it is found that the domain of YBCO grain grown from the NdBCO seed can grow up to the whole samples co-doped with GdW2411 and Y2O3 except the sample with y=0.5wt%. The levitation force of YBCO bulks is increasing with Y2O3 addition when y≤0.3wt%, and decreasing with the additions of Y2O3 when y> 0.3wt%, the largest levitation force is obtained when x=4wt% and y=0.3wt%. The microstructures indicate that the GdW2411 particles are uniformly distributed in the YBCO matrix, and the particle size is about 200nm, Y2O3 addition may refine Y211 particle.