M. Choucair

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Publications (3)0 Total impact

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    Article: Graphene doping to enhance flux pinning and supercurrent carrying ability in magnesium diboride superconductor
    X Xu, S. X. Dou, X L Wang, J H Kim, J. A. Stride, M. Choucair, W. K. Yeoh, R. K. Zheng, S P Ringer
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    ABSTRACT: It has been shown that graphene doping is sufficient to lead to an improvement in the critical current density - field performance (Jc(B)), with little change in the transition temperature in MgB2. At 3.7 at% graphene doping of MgB2 an optimal enhancement in Jc(B) was reached by a factor of 30 at 5 K and 10 T, compared to the un-doped sample. The results suggested that effective carbon substitutions by grapheme, 2D nature of grapheme and the strain effect induced by difference thermal coefficient between single grapheme sheet and MgB2 superconductor may play an important role in flux pinning enhancement.
    01/2010;
  • Conference Proceeding: Tuning the defect density in chemically synthesized graphene
    M. Choucair, J.A. Stride
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    ABSTRACT: Gram-scale quantities of graphene sheets can be synthesized in a bottom-up chemical approach and we have sought to address the extent of the defect density using various characterization techniques which include X-ray diffraction, high resolution transmission electron microscopy, single area electron diffraction, Raman spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. It was found that the chemically synthesized graphene sheets have a tendency to stack without inter-planar coherence such as that found in graphite. The driving force behind this stacking is believed to be due to ¿-¿ interactions between overlaid carbon sheets. The overall defect density was shown to decrease by simply varying the carbon precursor used in the chemical synthesis.
    Nanotechnology, 2009. IEEE-NANO 2009. 9th IEEE Conference on; 08/2009
  • Article: Enhanced reversible lithium storage in a nanosize silicon/graphene composite
    S. L. Chou, J. Z. Wang, M. Choucair, H. K. Liu, J. A. Stride, S. X. Dou
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    ABSTRACT: Si/graphene composite was prepared by simply mixing of commercially available nanosize Si and graphene. Electrochemical tests show that the Si/graphene composite maintains a capacity of 1168 mAh g(-1) and an average coulombic efficiency of 93% up to 30 cycles. EIS indicates that the Si/graphene composite electrode has less than 50% of the charge-transfer resistance compared with nanosize Si electrode, evidencing the enhanced ionic conductivity of Si/graphene composite. The enhanced cycling stability is attributed to the fact that the Si/graphene composite can accommodate large volume charge of Si and maintain good electronic contact. (C) 2009 Elsevier B.V. All rights reserved.
    Electrochemistry Communications. 12(2):303-306.
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