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Title: A trapped magnetic field of 3T in homogeneous, bulk MgB2 superconductors fabricated by a Modified Precursor Infiltration and Growth (MPIG) process
Authors: Bhagurkar, AG
Yamamoto, A
Anguilano, L
Dennis, AR
Durrell, JH
Babu, NH
Cardwell, DA
Keywords: MgB2;Infiltration and growth;Trapped field
Issue Date: 2016
Publisher: IOP Publishing
Citation: Superconductor Science and Technology, 29(3): pp. 1-9, (2016)
Abstract: The wetting of boron with liquid magnesium is a critical factor in the synthesis of MgB2 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 MgB2 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 MgB2 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 MgB2 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.
ISSN: 035008
Appears in Collections:The Experimental Techniques Centre

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