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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. |
URI: | http://iopscience.iop.org/article/10.1088/0953-2048/29/3/035008/meta;jsessionid=945BFB96F09B64D196B677805067F768.c3.iopscience.cld.iop.org http://bura.brunel.ac.uk/handle/2438/11922 |
DOI: | http://dx.doi.org/10.1088/0953-2048/29/3/035008 |
ISSN: | 035008 035008 1361-6668 |
Appears in Collections: | The Experimental Techniques Centre |
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