Microscopic unravelling of nano-carbon doping in MgB2 superconductors fabricated by diffusion method

Authors

Derek Chi Kian Wong, University of SydneyFollow
Wai Kong Yeoh, University of Sydney, University of WollongongFollow
Kaludewa Sujeewa Buddhimali De Silva, University of WollongongFollow
A Kondyurin, University of Sydney
Peite Bao, University of Sydney
W X. Li, Shanghai University
Xun Xu, University of WollongongFollow
Germanas Peleckis, University of WollongongFollow
S X. Dou, University of WollongongFollow
Simon Peter Ringer, University of Sydney
Rongkun Zheng, University of Sydney

RIS ID

101222

Publication Details

Wong, D. C. K., Yeoh, W. K., De Silva, K. S. B., Kondyurin, A., Bao, P., Li, W. X., Xu, X., Peleckis, G., Dou, S. X., Ringer, S. P. & Zheng, R. K. (2015). Microscopic unravelling of nano-carbon doping in MgB₂ superconductors fabricated by diffusion method. Journal of Alloys and Compounds, 644 900-905.

Abstract

We investigated the effects of nano-carbon doping as the intrinsic (B-site nano-carbon substitution) and extrinsic (nano-carbon derivatives) pinning by diffusion method. The contraction of the in-plane lattice confirmed the presence of disorder in boron sublattice caused by carbon substitution. The increasing value in full width half maximum (FWHM) in the X-ray diffraction (XRD) patterns with each increment in the doping level reveal smaller grains and imperfect MgB₂ crystalline. The strain increased across the doping level due to the carbon substitution in the MgB₂ matrix. The broadening of the T_c curves from low to high doping showed suppression of the connectivity of the bulk samples with progressive dirtying. At high doping, the presence of B₄C region blocked the Mg from reacting with crystalline B thus hampering the formation of MgB₂. Furthermore, the unreacted Mg acted as a current blocking phase in lowering down the grain connectivity hence depressing the J_c of the 10% nano-carbon doped MgB₂ bulk superconductor.