MgO or SrSO 4 particulates were introduced into Bi-2212/Ag tapes during the fabrication process with the intention of producing flux pinning centres. It was found that (i) MgO or SrSO 4 normal particles added to Bi-2212 superconductor do not react chemically with or corrupt the Bi-2212 phase, but MgO may alter the phase evolution during the partial melting and the solidification of Bi-2212 and reduce the second-phase inclusions, (ii) MgO addition may enhance the flux pinning potential in a certain region of temperature and magnetic field (the contributions of MgO addition to the flux pinning potential are still not clear) and (iii) SrSO 4 addition appears to have no effect on the properties of finished samples.

With the aid of transmission electron microscopy, the phenomenon of additional superstructure along [Formula: see text] direction was observed for a sample of Bi 1.7 Pb 0.3Sr2 Ca 1.8 Ba 0.2 Cu 3 O y, and two kinds of modulation mode along b axis was found to coexist in this sample. The images of SEM showed that the addition of Ba ions improved the property of two-dimensional growth. The results of XRD indicated that the substitution of Ba 2+ for Ca 2+ increased the volume fraction of the high-Tc phase (Tc>100 K). From the initial part of dc magnetization curve, it is estimated that about 36 percent of the sample volume is in the 110 K superconducting phase at 77 K. Its frozen magnetic flux density is about 8.6 G, which is 5–6 G higher than that of general Pb-doped sample, and its zero-resistance temperature can reach as high as 111 K. These changes of physical properties may be related to the adjustment of the microstructure.

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