Improvements in the processing of large grain, bulk Y-Ba-Cu-O superconductors via the use of additional liquid phase
Improvements in the processing of large grain, bulk Y-Ba-Cu-O superconductors via the use of additional liquid phase
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DOI：
10.1088/0953-2048/30/1/015017
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发表时间：
2017-01-01
影响因子：
3.6
通讯作者：
Cardwell, David A.
中科院分区：
文献类型：
--
作者：
Congreve, Jasmin V. J.;Shi, Yunhua;Cardwell, David A.
Y-Ba-Cu-O（YBCO）大块超导体广泛应用的一个主要限制是顶部籽晶熔体生长（TSMG）工艺的相对复杂性和低产量，这些材料通常通过该工艺制造。在先前关于其中初级生长失败的样品的再循环的工作中已经证明，提供额外的富液相以补充在失败的生长过程中损失的液体导致相对高质量的再循环样品的可靠生长。在本文中，我们描述了适应的液相富集技术的主要TSMG制造工艺。我们进一步描述了观察到的样品的微观结构和超导性能之间的差异与额外的富液相和控制样品生长使用传统的TSMG过程。我们观察到，引入额外的富液相导致在生长前沿形成更高浓度的Y物种，这反过来又导致在生长前沿形成更均匀的组合物。重要的是，在生长前沿的增加的均匀性直接导致Y-211夹杂物在超导Y-123相基质中的分布的增加的均匀性和导致更均匀的Y-123相本身。总的来说，提供一个额外的富液相显着提高了通过样品厚度的晶粒生长的可靠性和这些样品的超导性能的大小和均匀性相比，由传统的TSMG工艺制造。
A major limitation to the widespread application of Y-Ba-Cu-O (YBCO) bulk superconductors is the relative complexity and low yield of the top seeded melt growth (TSMG) process, by which these materials are commonly fabricated. It has been demonstrated in previous work on the recycling of samples in which the primary growth had failed, that the provision of an additional liquid-rich phase to replenish liquid lost during the failed growth process leads to the reliable growth of relatively high quality recycled samples. In this paper we describe the adaptation of the liquid phase enrichment technique to the primary TSMG fabrication process. We further describe the observed differences between the microstructure and superconducting properties of samples grown with additional liquid-rich phase and control samples grown using a conventional TSMG process. We observe that the introduction of the additional liquid-rich phase leads to the formation of a higher concentration of Y species at the growth front, which leads, in turn, to a more uniform composition at the growth front. Importantly, the increased uniformity at the growth front leads directly to an increased homogeneity in the distribution of the Y-211 inclusions in the superconducting Y-123 phase matrix and to a more uniform Y-123 phase itself. Overall, the provision of an additional liquid-rich phase improves significantly both the reliability of grain growth through the sample thickness and the magnitude and homogeneity of the superconducting properties of these samples compared to those fabricated by a conventional TSMG process.