The effects of C substitution and disorder on the field dependent critical current density in MgB2 with nano-SiC additions |
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| Authors: | SK Chen X Xu JH Kim SX Dou JL MacManus-Driscoll |
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| Institution: | 1. Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia;2. Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia;3. Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK |
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| Abstract: | In this work, nano sized SiC powders were mixed with Mg and B and reacted by either a one-step insitu or two-step method resulted in different level of C substitution. X-ray diffraction shows the presence of Mg2Si signifying that the reaction between SiC and Mg occurred leading to the release of C in samples reacted in one-step method. Moreover, the much reduced value of a-axis indicates C substitution took place. Resistivity measurements showed higher intragrain scattering owing to a higher density of defects and/or impurities. These samples also show higher Hirr and Hc2 at 20 K in comparison to samples with mainly unreacted SiC (hence lower C substitution). More importantly, their Jc’s are more insensitive to high magnetic field (>4 T) at 6 K. However, at 20 K the effect of C content on Jc(H) is less pronounced. Finally, the order of magnitude of Jc(H) at both 6 K and 20 K is rather dominated by pinning. |
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| Keywords: | MgB2 Carbon substitution Upper critical field Critical current density |
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