Enhancement of flux pinning in (Bi, Pb)-2223/Ag tapes doped with MgO nanorods

MgO nanorods with an average diameter of 30 nm and lengths of 2-3 mum have been incorporated into (Bi, Pb)-2223/Ag tapes. X-ray diffraction analysis shows that a small addition of MgO nanorods does not obstruct the formation of (Bi, Pb)-2223 phase. Scanning electron microscopy images show that the size of the (Bi, Pb)-2223 grains and the degree of texture in the samples doped with 1 wt% of MgO nanorods are improved. Transmission electron microscopy observation also shows that the MgO nanorods do not agglomerate or grow during the sintering process. The transport critical current densities of the samples doped with 1 wt% of MgO nanorods are enhanced noticeably at high temperatures and magnetic fields and the irreversibility line of the samples doped with 1 wt% of MgO nanorods shifts to higher temperatures and magnetic fields as compared with the undoped samples. The possible pinning mechanism of the samples doped with MgO nanorods is discussed. The results reveal that the introduction of MgO nanorods as columnar defects can effectively enhance the flux pinning.