Effect of SiO₂ and SiC doping on the powder-in-tube processed MgB₂ tapes

Effect of SiO₂ and SiC nano-powder doping was investigated for the powder-in-tube processed MgB₂/Fe tapes. Mg or MgH₂ powder was used as the Mg source of starting materials, and heat treatment was carried out at 600 °C for 1 h. These heat treatment conditions of lower temperature and shorter heating time are advantageous from the aspect of practical production processes. MgH₂ powder improved the connection of MgB₂ grains and prevented oxidation of MgB₂. SiC and SiO₂ doping greatly enhanced the critical current density (J_C) values of the tapes prepared with Mg + B powder. However, only the SiC doping was effective in enhancing J_C values for MgH₂ + B powder. SiC doping decreased magnetic field sensitivity of J_C, while SiO₂ doping did not change the field dependence of J_C. The SiC doped tape showed transport J_C value of about 6 500 A cm⁻² at 4.2 K and in the magnetic field of 12 T. The irreversibility field increased from 17 T to 23 T by the SiC doping.