The JC–B performance of MgB2/Fe tapes was enhanced in high magnetic fields by the addition of an appropriate amount of nm-sized Si3N4 particles. At 4.2K and in 12T, the optimum doped samples (1% and 1.67%) exhibited almost twice the value of JC as that of undoped tape. The enhancement of JC–B performance was considered to arise from the introduction of extra pinning centers and an improved core density. It was noted that the dependence of JC upon the magnetic field did not change in differently Si3N4-doped samples; indicating that the flux-pinning centers introduced by the addition of nm-Si3N4 particles were limited. Considering the small TC drop and the residual Si3N4 particles in the heat-treated tapes, it was proposed that the Si3N4 particles appeared as additives in MgB2. The added and/or reaction induced nm particles could serve as effective pinning centers.

Enhanced JC–B Performance in MgB2/Fe Tapes with Nanometre Si3N4 Addition. C.H.Jiang, T.Nakane, H.Kumakura: Superconductor Science and Technology, 2005, 18, 902-6