Phthalocyanine doping to improve critical current densities in MgB2tapes

Phthalocyanine-doped MgB2 tapes were prepared by the in situ powder-in-tube method. The relationships between the critical current properties, crystallinity and microstructure were studied as a function of the phthalocyanine doping level. It is found that both Hirr and Hc2 were improved when MgB2 samples were doped with phthalocyanine, which are mainly attributed to the effective carbon substitution and enhanced flux pinning strength caused by very fine grain sizes. Furthermore, compared to pure samples, the MgO content remained almost unchanged in all doped tapes, which is very beneficial to having better grain connectivity in MgB2. Significantly improved Jc was obtained in the phthalocyanine-doped MgB2 tapes, especially under high magnetic fields.