Resistivity and Magneto-Optical Evidence for Variable and Incomplete Connectivity in Dense, High Critical Current Density C-alloyed Magnesium Diboride

B. J. Senkowicz; A. A. Polyanskii; R. J. Mungall; E. E. Hellstrom; D. C. Larbalestier

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Resistivity and Magneto-Optical Evidence for Variable and Incomplete Connectivity in Dense, High Critical Current Density C-alloyed Magnesium Diboride

B. J. Senkowicz·A. A. Polyanskii·R. J. Mungall·E. E. Hellstrom·D. C. Larbalestier

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Abstract

Carbon-doped magnesium diboride was fabricated from pre-reacted pure MgB2 by mechanical alloying. The sample set had excellent critical current densities Jc(8T,4.2K) ranging from 15-60 kA/cm2, depending on composition. Magneto-optical imaging detected regions up to 0.5 mm in size which were nearly 100% dense with Jc 2-6 times that of the matrix. Evaluation of resistivity curves using the Rowell method predicts that only 10-50% of the cross sectional area carries the normal state measurement current, suggesting that considerable increases in Jc in these ~80% dense MgB2 samples would be possible with complete grain and particle connectivity.

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B. J. Senkowicz, A. A. Polyanskii, R. J. Mungall, E. E. Hellstrom, D. C. Larbalestier. 2006-03-29. Resistivity and Magneto-Optical Evidence for Variable and Incomplete Connectivity in Dense, High Critical Current Density C-alloyed Magnesium Diboride. https://arxiv.org/abs/cond-mat/0603800

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