Fabrication, microstructure and critical current density of pure and Cu doped MgB2 thick films on Cu, Ni and stainless steel substrates by short-time in-situ reaction

Pure and Cu doped MgB2 think films have been prepared on Cu, Ni and stainless steel substrates using a short-time sintering method. Results showed that single MgB2 phase films can be easily formed in a short period of time (3 min) at temperatures above 700 °C. Un-doped MgB2 films were found to be loosely attached to the Ni and stainless steel substrates. However, the MgB2 with Cu powders addition adhered well to the substrates without serious degradation of Tc and flux pinning. The Jc increased one order of magnitude and irreversibility field determined from M–H loops also increased when sintering temperature increased from 745 to 900 °C. Jc values in the range of 1–9×105 A/cm2 at 15 K have been achieved for both doped and un-doped films sintered at 900 °C for 3 min.