The effect of citric and oxalic acid doping on the superconducting properties ofMgB2

Abstract

In this paper we report the effect of carbon doping on the structural and superconducting propertiesof MgB2 using citric and oxalic acids as carbon sources. The bulk polycrystalline sampleshave been synthesized via a standard solid state reaction route with compositionMgB2+x wt% of citricand oxalic acids (x = 0, 5 and 10). The x-ray diffraction results reveal the formation of dominantlyMgB2 with only a small amount of impurity phase MgO and substitution of C at the B site ofMgB2 for both dopants. Improvements in the upper critical field(HC2), irreversibilityfield (Hirr) and highfield (>2.5 T) criticalcurrent density (JC) have been observed on C doping in the samples. The correlations between superconductingproperties and structural characteristics of the samples are described and discussed in thispaper.