Cu and nano-SiC doped MgB 2 thick films on Ni substrates processed using a very short-time in situ reaction

Abstract

Pure and doped MgB 2 thick films were fabricated on Ni substrates by applying a coating mixture of powders of elemental magnesium and boron with varying amounts of elemental Cu and nano-SiC powders, followed by a high pressure press, and sintering at 840 or 900 °C for just a few minutes, and then quenching in liquid nitrogen. For films sintered at 900 °C, critical current densities J c were achieved as high as 1.4 × 10 6 A/cm 2 at 20 K and 2.3 × 10 5 A/cm 2 at 20 K and 2 T for the pure and SiC added films. Films doped with 5 wt.% of Cu powders were observed to have better adherence to the Ni substrate without degradation in T c, and J c was found to be slightly decreased, but still remains as high as 7 × 10 5 A/cm 2 at 20 K in zero field. It was observed that J c and irreversibility field increase with an increasing sintering temperature up to 900 °C. Furthermore, nano-SiC addition has significantly improved the irreversibility field compared to undoped MgB 2 films.