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Improvements in the processing of large grain, bulk Y–Ba–Cu–O superconductors via the use of additional liquid phase

Published version
Peer-reviewed

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Authors

Congreve, JVJ 
Dennis, AR 
Durrell, JH 
Cardwell, DA 

Abstract

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.

Description

Keywords

top seeded melt growth, YBCO, Y-211, microstructure, liquid rich phase, bulk high temperature superconductor, Y-123 matrix

Journal Title

Superconductor Science and Technology

Conference Name

Journal ISSN

0953-2048
1361-6668

Volume Title

30

Publisher

Institute of Physics
Sponsorship
Engineering and Physical Sciences Research Council (EP/K02910X/1)
Engineering and Physical Sciences Research Council (EP/P00962X/1)
The authors acknowledge support from the Engineering and Physical Sciences Research Council EP/K02910X/1.
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