The effect of facet lines on critical current density and trapped field in bulk RE-Ba-Cu-O single grains

TY - JOUR

T1 - The effect of facet lines on critical current density and trapped field in bulk RE-Ba-Cu-O single grains

AU - Shi, Yun Hua

AU - Mousavi, Tayebeh

AU - Dennis, Anthony R.

AU - Ainslie, Mark D.

AU - Speller, Susannah C.

AU - Grovenor, Chris R. H.

AU - Durrell, John H.

AU - Cardwell, David A.

N1 - Funding Information: The authors acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) Grant No. EP/T014679/1. The work of M D Ainslie was carried out while affiliated with the Bulk Superconductivity Group, Department of Engineering, University of Cambridge, and supported by an EPSRC Early Career Fellowship, EP/P020313/1. Publisher Copyright: © 2022 The Author(s). Published by IOP Publishing Ltd.

PY - 2022/8/19

Y1 - 2022/8/19

N2 - Bulk, single grain RE-Ba-Cu-O (where RE = rare earth or yttrium) [(RE)BCO] high temperature superconductors could potentially be used to generate stable magnetic fields for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). In these applications, however, the homogeneity of the magnetic field is of critical importance. As a result, the spatial distribution of critical current density, Jc, within the bulk single grain and the effects of the magnetisation process, which are primary drivers of the uniformity of the achievable trapped magnetic field, are fundamental to assessing the performance of these technologically important materials. This paper reports the systematic measurement of the distribution of Jc-B at 77 K over a vertical cross-section of a single grain along a facet line and through the seed crystal [(110)-F] at 20 positions within a 20 mm diameter Gd-Ba-Cu-O sample in an attempt to understand and assess the distribution of Jc along this microstructural feature. A comparison of the data within the whole vertical plane across the seed measured along the a or b direction within the [(100)-a] plane shows that Jc-B at 77 K at the facet line is more than 10% higher for applied fields between 0.2 T and 2.5 T. The effect of the Jc-B relationship of the facet line on the overall trapped field measured in an individual bulk sample was investigated by measuring the magnitudes of trapped fields and their contour maps for sections cut from four single grain samples of GdBCO-Ag at different sizes and shapes parallel to the ab-plane from the top to the bottom of the bulk sample. Based on the results reported here, we demonstrate a method to achieve more uniform trapped fields through an optimal arrangement of an assembly of sections of individual GdBCO single grains.

AB - Bulk, single grain RE-Ba-Cu-O (where RE = rare earth or yttrium) [(RE)BCO] high temperature superconductors could potentially be used to generate stable magnetic fields for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). In these applications, however, the homogeneity of the magnetic field is of critical importance. As a result, the spatial distribution of critical current density, Jc, within the bulk single grain and the effects of the magnetisation process, which are primary drivers of the uniformity of the achievable trapped magnetic field, are fundamental to assessing the performance of these technologically important materials. This paper reports the systematic measurement of the distribution of Jc-B at 77 K over a vertical cross-section of a single grain along a facet line and through the seed crystal [(110)-F] at 20 positions within a 20 mm diameter Gd-Ba-Cu-O sample in an attempt to understand and assess the distribution of Jc along this microstructural feature. A comparison of the data within the whole vertical plane across the seed measured along the a or b direction within the [(100)-a] plane shows that Jc-B at 77 K at the facet line is more than 10% higher for applied fields between 0.2 T and 2.5 T. The effect of the Jc-B relationship of the facet line on the overall trapped field measured in an individual bulk sample was investigated by measuring the magnitudes of trapped fields and their contour maps for sections cut from four single grain samples of GdBCO-Ag at different sizes and shapes parallel to the ab-plane from the top to the bottom of the bulk sample. Based on the results reported here, we demonstrate a method to achieve more uniform trapped fields through an optimal arrangement of an assembly of sections of individual GdBCO single grains.

KW - (RE)BCO

KW - bulk superconductors

KW - facet lines

KW - homogeneity

KW - J distribution

KW - trapped field

KW - uniformity

UR - http://www.scopus.com/inward/record.url?scp=85136673719&partnerID=8YFLogxK

U2 - 10.1088/1361-6668/ac883d

DO - 10.1088/1361-6668/ac883d

M3 - Article

AN - SCOPUS:85136673719

SN - 0953-2048

VL - 35

JO - Superconductor Science and Technology

JF - Superconductor Science and Technology

IS - 10

M1 - 105002

ER -