Buffer Pellets for High-Yield, Top-Seeded Melt Growth of Large Grain Y-Ba-Cu-O Superconductors
Buffer Pellets for High-Yield, Top-Seeded Melt Growth of Large Grain Y-Ba-Cu-O Superconductors
复制标题
DOI：
10.1021/cg501813y
复制
发表时间：
2015-03-01
影响因子：
3.8
通讯作者：
Cardwell, David A.
中科院分区：
文献类型：
--
作者：
Kumar, Namburi Devendra;Shi, Yunhua;Cardwell, David A.
单晶粒（RE）-Ba-Cu-O [（RE）BCO）]大块高温超导体作为俘获场磁体在一系列工程设备中具有显著的应用潜力。然而，这是不平凡的制造（RE）BCO的单个晶粒由于生长过程的复杂性，特别是当样品直径超过25毫米。特别是，与籽晶相关的困难可能会导致不良的晶粒生长或完全生长失败。我们采用了一种优化的缓冲技术，这是确定通过优化目标的关键参数的缓冲颗粒，包括选择的缓冲颗粒的组成和它的纵横比，可靠的制造大，单颗粒的（RE）BCO。缓冲丸组合物的潜在候选者已被确定为产生成功的晶粒生长和良好的超导性能。作为本研究的一部分，还确定了缓冲颗粒的最佳纵横比。已经证明用晶种覆盖的优化的缓冲剂颗粒作为有效的晶种有效地工作，并且显著地帮助Y-123相的生长。我们表明，这种优化的缓冲技术改善了与界面应力（通常发生在种子/样品界面）和粮食污染的问题。我们已经制备了一个直径为40.8毫米的单颗粒大块超导体和超过25个单颗粒的样品，直径在25-35毫米的范围内显着改进的顶部籽晶熔体生长工艺。
Single-grain, (RE)-Ba-Cu-O [(RE)BCO)] bulk high-temperature superconductors have significant potential for application as trapped field magnets in a range of engineering devices. However, it is not trivial to fabricate single grains of (RE)BCO due to the complexity of the growth process, especially when the sample diameter exceeds 25 mm. In particular, difficulties associated with the seed crystal can lead to poor grain growth or to complete growth failure. We have employed an optimized buffer technique, which was determined by optimizing targeted critical parameters of the buffer pellet, including the choice of the buffer pellet composition and its aspect ratio, for the reliable fabrication of large, single grains of (RE)BCO. Potential candidates for the buffer pellet composition have been identified to yield successful grain growth and good superconducting properties. The optimum aspect ratio of the buffer pellet was also determined as part of this study. The optimized buffer pellet capped with the seed crystal has been demonstrated to work effectively as an efficient seed crystal and to aid significantly the growth of the Y-123 phase. We show that this optimized buffer technique ameliorates problems associated with both interfacial stress (commonly occurring at the seed/sample interface) and problems of grain contamination. We have fabricated a 40.8 mm diameter single-grain bulk superconductor and more than 25 single-grain YBCO samples with diameters in the range 25-35 mm by a significantly improved top-seeded melt growth process.