中文摘要：

本文采用顶部籽晶熔融织构法（TSMTG）研究了Gd2Ba4CuNbOy（GdNb2411）的掺杂量及其初始粉体粒度对单畴GdBCO超导块材磁悬浮力的影响．制备单畴GdBCO超导块材的初始成份为GdBa2Cu3O7-δ：Gd2BaCuO5：GdNb2411=1：（0．4-x）：x，x=0、0．02、0．06、0．1、0．14；GdNb2411粒子的初始粒度（d）范围分别在0≤d≤40m、40≤d≤61m、61≤d≤120m、120≤d≤180m．结果表明：（1）GdBCO超导块材的生长形貌与其掺杂量x密切相关，当x≤0．06时，样品具有单畴形貌，且表面光滑平整；当x〉0．06mol时，样品仍具有单畴形貌，但其表面出现皱褶现象；（2）随着x的增加，样品的磁悬浮力先增大后减小，当x=0．06mol时达到最大25N．（3）掺入样品的GdNb2411粉体粒度越小，最终在样品中生成的GdNb2411粒子的粒径也越小．（4）当固定x=0．06时发现，随着掺杂GdNb2411粉体粒度的减小，单畴GdBCO超导块材的磁悬浮力逐渐增大，当粒度d≤40mm时，样品中的GdNb2411粒度约在100nm-250nm之间，相应样品的磁悬浮力最大，约25N．这些结果对进一步提高GdBCO超导块材的质量具有一定的指导意义．

英文摘要：

Single domain GdBCO bulk superconductors, with compositions of GdBa2Cu3O7-δ： Gd2 BaCuO5 （Gd211） ： Gd2Ba4CuNbOy（GdNb2411） =1 ： （0. 4-x） ： x, have been fabricated successfully by the top- seeding melt texture growth process （TSMTG）, x=0, 0. 02, 0. 06, 0. 1, 0. 14. four kind of GdNb2411 particles with different size（d）, 0≤d≤40mm,40〈d≤61m,61〈d≤120m,120〈d≤180m. The effect of the particles size and content of GdNb2411 powder on the growth morphology and the magnetic levitation force properties of single domain GdBCO bulk superconductors have been investigated. The result shows that., single domain GdBCO bulk samples can be fabricated with the GdNb2411 particle additions up to x= 0. 14, but the surface morphology of the samples is closely related with the doping content x, it is of a smooth faced plane for the samples with x≤0. 06mol, but it is of a wrinkle surface for the samples with x≥0. 08mol. The levitation force of samples increases first and then decreases with the increasing of x, the largest levitation force of 25N is obtained in the samples with x= 0. 06mol. The levitation force of the GdBCO bulks with different particles size of GdNb2411 powder indicates that the smaller the GdNb2411 particles size, the larger the levitation force. The results is very important for further improvement the quality of GdBCO bulk superconductors.