Investigation of lauric acid dopant as a novel carbon source in MgB ₂ wire

We fabricated lauric acid (LA) doped MgB₂ wires and investigated the effects of the LA doping. For the fabrication of the LA-doped MgB ₂ wires, B powder was mixed with LA at 0-5 wt.% of the total amount of MgB₂ using an organic solvent, dried, and then the LA-treated B and Mg powders were mixed stoichiometrically. The powder mixture was loaded into an Fe tube and the assemblage was drawn and sintered at 900 °C for 3 h under an argon atmosphere. We observed that the LA doping induced the substitution of C for the B sites in MgB₂ and that the actual content of C increased monotonically with increasing LA doping level. The LA-doped MgB₂ wires exhibited a lower critical temperature (T_c), but better critical current density (J_c) behavior in a high magnetic field: the 5 wt.% LA-doped sample had a J_c value of 5.32 x 10 ³ A/cm², which was 2.17 times higher than that of the pristine sample (2.45 x 10³ A/cm²) at 5 K and 6 T, suggesting that LA is an effective C dopant in MgB₂ for enhancing the high-field J_c performance.