N Ojha et al 2009 Supercond. Sci. Technol. 22 125014 doi:10.1088/0953-2048/22/12/125014
N Ojha1, V K Malik2, Rashmi Singla1, C Bernhard2 and G D Varma1
Show affiliationsIn this paper we report the effect of carbon doping on the structural and superconducting properties of MgB2 using citric and oxalic acids as carbon sources. The bulk polycrystalline samples have been synthesized via a standard solid state reaction route with composition MgB2+x wt% of citric and oxalic acids (x = 0, 5 and 10). The x-ray diffraction results reveal the formation of dominantly MgB2 with only a small amount of impurity phase MgO and substitution of C at the B site of MgB2 for both dopants. Improvements in the upper critical field (HC2), irreversibility field (Hirr) and high field (>2.5 T) critical current density (JC) have been observed on C doping in the samples. The correlations between superconducting properties and structural characteristics of the samples are described and discussed in this paper.
74.25.Op Mixed states, critical fields, and surface sheaths
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.62.Dh Effects of crystal defects, doping and substitution
Issue 12 (December 2009)
Received 2 July 2009, in final form 3 September 2009
Published 23 October 2009
N Ojha et al 2009 Supercond. Sci. Technol. 22 125014
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