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A trapped magnetic field of 3 T in homogeneous, bulk MgB<inf>2</inf> superconductors fabricated by a modified precursor infiltration and growth process

Bhagurkar, AG and Yamamoto, A and Anguilano, L and Dennis, AR and Durrell, JH and Hari Babu, N and Cardwell, DA (2016) A trapped magnetic field of 3 T in homogeneous, bulk MgB<inf>2</inf> superconductors fabricated by a modified precursor infiltration and growth process. Superconductor Science and Technology, 29. ISSN 0953-2048

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Abstract

© 2016 IOP Publishing Ltd. The wetting of boron with liquid magnesium is a critical factor in the synthesis of MgB 2 bulk superconductors by the infiltration and growth (IG) process. Poor wetting characteristics can therefore result potentially in non-uniform infiltration, formation of defects in the final sample structure and poor structural homogeneity throughout the bulk material. Here we report the fabrication of near-net-shaped MgB 2 bulk superconductors by a modified precursor infiltration and growth (MPIG) technique. A homogeneous bulk microstructure has subsequently been achieved via the uniform infiltration of Mg liquid by enriching pre-reacted MgB 2 powder within the green precursor pellet as a wetting enhancer, leading to relatively little variation in superconducting properties across the entire bulk sample. Almost identical values of trapped magnetic field of 2.12 T have been measured at 5 K at both the top and bottom surfaces of a sample fabricated by the MPIG process, confirming the uniformity of the bulk microstructure. A maximum trapped field of 3 T has been measured at 5 K at the centre of a stack of two bulk MgB 2 samples fabricated using this technique. A steady rise in trapped field was observed for this material with decreasing temperature down to 5 K without the occurrence of flux avalanches and with a relatively low field decay rate (1.5%/d). These properties are attributed to the presence of a fine distribution of residual Mg within the bulk microstructure generated by the MPIG processing technique.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div C > Materials Engineering
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:31
Last Modified: 07 Sep 2017 01:47
DOI: