中文摘要：

本文采用顶部籽晶熔渗方法（TSIG），研究了不同粒径纳米Y2Ba4CuBiOy粒子对单畴YBCO超导块材的生长形貌、微观结构及其磁悬浮力的影响．实验所用纳米Y2Ba4CuBiOy粉体的平均粒度分别为283．0nm，170．4nm以及82．5nm，每种粉体在YBCO超导块材中的含量均为2wt％．研究结果表明：在掺杂量为2wt％的情况下，Y2Ba4CuBiOy粉体的粒度并不影响样品的宏观形貌，均可制备出单畴YBCO块材；并且成功地将纳米Y2Ba4CuBiOy粒子引入单畴YBCO块材中，且使其均匀分布，但样品中的Y2Ba4CuBiOy粒子均小于其初始粉体的粒度，分别减小到270nm，150nm和50nm；随着Y2Ba4CuBiOy粉体初始粒度的减小，样品的磁悬浮力逐渐增大，分别为10N，17N，22N．该结果为进一步研究纳米磁通钉扎中心的引入方法及提高YBCO超导块材的性能有重大意义．

英文摘要：

Single domain YBCO bulk superconductors are fabricated by the top-seeded infiltration and growth process（TSIG）. The effects of different particle size Y2Ba4CuBiOy nanoparticles doped on the growth morphology, microstrncture and levitation force of single domain YBCO bulk superconductors are investigated. The mean diameters of the initial Y2Ba4CuBiOy nanoparticles respectively are 283 nm, 170.4 nm and 82.5 nm, and the amount of Y2Ba4CuBiOyadded to Y2BaCuO5 is 2 wt%. The results show that the single domain YBCO bulk superconductors can be fabricated, and the surface of the sample has significant cross pattern and four single domain sectors become smooth and flat. The second phase Y2Ba4CuBiOy nanoparticles are well-distributed into the single domain YBCO bulk samples, and the particles sizes of Y2Ba4CuBiOy nanoparticles in the YBCO bulk sample are respectively 270 nm, 150 nm and 50 nm, smaller than that the initial powder. The magnetic levitation forces of the samples increase gradually with the decrease of initial powders of Y2Ba4CuBiOy nanoparticles, which are respectively 10 N, 17 N and 22 N. The results are very important for further studying the method of flux pinning of nanoparticles and improving the properties of YBCO bulk superconductors.