【摘要】 顶部籽晶熔融织构生长法(TSMTG)是制备大尺寸单畴YBCO超导块材最有效的方法之一,然而,TSMTG法却存在着样品易收缩、变形等严重问题.为了解决这一问题,人们发明了顶部籽晶熔渗生长法(TSIG).但传统的TSIG法需要制备Y2Ba Cu O5(Y211),YBa2Cu3Oy(Y123),Ba Cu O2三种粉体,不仅过程复杂、费时费力、耗能污染,且最大的缺陷是无法控制样品中的Y211粒子含量.为了解决这些技术难题,发明了一种新TSIG法,用Y2O3+1.2Ba Cu O2混合粉替代传统的Y211固相源,用Y2O3,Ba Cu O2和Cu O混合粉替代传统的(Y123+3Ba Cu O2+2Cu O)液相源.采用这种新TSIG法,成功地制备出了直径为59和93 mm的单畴YBCO超导块材.通过对采用传统和新TSIG法制备单畴YBCO超导块材的生长速率、磁悬浮力和微观结构的研究发现:(1)采用新TSIG法后,YBCO超导块材的生长速率达到传统方法的1.7倍;(2)采用新TSIG法制备的单畴YBCO超导块材的磁悬浮力比传统方法制备的样品高出65%以上;(3)采用新TSIG法制备单畴YBCO超导块材,样品中的Y211粒子平均粒径约为1μm,明显小于传统TSIG方法所制备样品的3.4μm,而且分布更合理、均匀,有效地提高了样品的磁通钉扎能力.在此基础上,制备出了目前国内最大尺寸(直径93 mm)单畴YBCO超导块材.这些结果表明,新TSIG法对于促进低成本、大尺寸、高质量单畴REBCO超导块材的产业化及其应用进程具有非常重要的指导意义和实用价值.更多还原

【Abstract】 The top seed melt-textured growth method(TSMTG) is a most effective method for the preparation of large size single domain YBCO bulk superconductors, but suffers from sample shrinkage and serious sample deformation problems during the TSMTG process; the top-seeded infiltration growth method(TSIG) was invented to overcome these problems. However, three different powders, comprising Y2 Ba Cu O5(Y211), YBa2Cu3Oy(Y123), and Ba Cu O2, must be prepared before fabrication of single domain YBCO bulk superconductors by the traditional TSIG method. This process is complicated, time-consuming, energy-consuming, and leads to atmospheric pollution, and it is also impossible to control the density and the distribution of the Y211 particles in the samples. To solve these important technical problems, we have invented a new TSIG method whereby a mixture of Y2O3 + 1.2 Ba Cu O2 powder is used as a new solid phase to replace the traditional solid-phase Y211, and a mixture of Y2O3, BaC u O2 and CuO powder is used as a new liquid phase rather than the traditional(Y123 + 3 Ba Cu O2 + 2 Cu O) phase. Using this new solid phase and liquid phase, single domain YBCO bulk superconductors with diameters of 59 mm and 93 mm have been successfully prepared by the proposed TSIG process. We found that:(1) the crystal growth rate of the single domain YBCO bulks prepared by the new TSIG process is approximately 1.7 times higher than that of similar samples prepared by the traditional TSIG method;(2) the levitation force of single domain YBCO bulks prepared by the new TSIG process is 1.65 times higher than that of samples prepared by the traditional TSIG method;(3) the Y211 particles prepared by the new TSIG process are much smaller in size and have a more reasonable distribution than in the samples prepared by the traditional TSIG method, and this can effectively improve the flux pinning force of the sample. These results indicate that the new TSIG process that was developed in our laboratory is a very important and highly practical method for the fabrication of low-cost, large size, high-quality single domain rare earth BCO(REBCO)-type bulk superconductors.更多还原