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Evidence for high inter-granular current flow in single-phase polycrystalline MgB2 superconductor

K. Kawano·J. S. Abell·M. Kambara·N Hari Babu·D. A. Cardwell
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Abstract

The distribution of magnetic field in single-phase polycrystalline bulk MgB2 has been measured using a Magneto-Optical (MO) technique for an external magnetic field applied perpendicular to the sample surface. The MO studies indicate that an inter-granular current network is readily established in this material and the current is not limited by weak-linked grain boundaries. The grain boundaries are observed to resist preferential magnetic field penetration, with the inter-grain mechanism dominating the current flow in the sample at temperatures up to 30K. The results provide clear evidence that the intra-granular current flow is isotropic. A critical current density of ~10^4 Acm-2 was estimated at 30K in a field of 150mT from the MO measurements. These results provide further evidence of the considerable potential for MgB2 for engineering applications.

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K. Kawano, J. S. Abell, M. Kambara, N Hari Babu, D. A. Cardwell. 2001-04-06. Evidence for high inter-granular current flow in single-phase polycrystalline MgB2 superconductor. https://doi.org/10.1063/1.1405807

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