A comparative study on the effect of doping of nanocarbon (C), nanodiamond, and the well-established nano-SiC in MgB2 is carried out under identical doping levels (C: 2.6 and 5.2 wt%) and processing conditions (800°C, 2 h). The bulk samples are prepared via powder-in-sealed-tube method. The XRD analysis shows no reacted or unreacted phases in the case of lightly nano-C-doped sample while all other doped samples show unreacted or/and reacted phases. The a-axis shrinkage is observed for all doped samples, among which nano-C-doped samples show maximum shrinkage, an evidence for C substitution at B sites. The C substitution is also confirmed by the analysis of full-width at half-maximum values for (100), (101), (002), and (110) peaks which are broadened. The C substitution together with the presence of nonsuperconducting phases decreases the TC to a small extent. The JC(H) is significantly enhanced for all doped samples compared with the pure sample among which MgB1.9C0.1 (nano-C) exhibits the best performance in JC enhancement up to a field of 8 T.
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Document Type: Research Article
National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695019, India
Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research,Bangalore 560064, India
Magnetic & Superconducting Materials Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, India
Publication date: 2011-04-01