A comparative study of pure, SiC, and C doped ${\mathrm{MgB}}_2$ wires has revealed that the SiC doping allowed C substitution and ${\mathrm{MgB}}_2$ formation to take place simultaneously at low temperatures. C substitution enhances $H_{c2}$, while the defects, small grain size, and nanoinclusions induced by C incorporation and low-temperature processing are responsible for the improvement in $J_c$. The irreversibility field ($H_{\mathrm{irr}}$) for the SiC doped sample reached the benchmarking value of 10 T at 20 K, exceeding that of NbTi at 4.2 K. This dual reaction model also enables us to predict desirable dopants for enhancing the performance properties of ${\mathrm{MgB}}_2$.

• Received 20 September 2006
• Corrected 20 March 2007

DOI:https://doi.org/10.1103/PhysRevLett.98.097002