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Effect of Carbon-Doping in Bulk Superconducting MgB2 Samples

M. Paranthaman·J. R. Thompson·D. K. Christen
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Abstract

Bulk superconducting samples of MgB2 were prepared by solid state reaction of stoichiometric quantities of Mg turnings and B in a sealed Ta cylinder at 890 C for 2 hours. The as-synthesized MgB2 samples had a Tc of 39 K, as defined as the onset of diamagnetism. The crystal symmetry was found to be hexagonal with lattice parameters, a=3.0856 A, and c=3.5199 A, similar to the literature values. To study the effect of carbon doping in MgB2, various C-containing samples of x varying from 0 to 1.00 in MgB2-xCx were prepared. Magnetic characterizations indicate that the Tc onset is same for pure and C-doped samples for x = 0.05, and 0.10. However, the shielding signal decreased monotonically with C content, apparently due to the presence of carbon on the grain boundaries that isolates grains and prevents flow of supercurrents on the perimeter.

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M. Paranthaman, J. R. Thompson, D. K. Christen. 2001-04-05. Effect of Carbon-Doping in Bulk Superconducting MgB2 Samples. https://doi.org/10.1016/s0921-4534(01)00424-5

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