Flux pinning due to MgO particle additions in partial-melting processed Bi-2212 bulk

In order to introduce effective pinning centers into Bi-2212 superconducting bulk, the addition of small MgO particles to Bi-2212 bulk and its effect on flux pinning were studied. Bi-2212 bulk samples were prepared by employing a normal partial-melting process, with a 0-8 vol.% of MgO particles addition. The morphology of Bi-2212 with MgO doping was investigated by means of XRD and EPMA. The magnetization and critical current densities (J(c)'s) in various magnetic fields and temperatures were measured by using a SQUID magnetometer. It was found that J(c) in samples with relatively large MgO particles introduced shows a larger value than that, in MgO-free sample, which implies that the MgO particles act as effective pinning centers and enhance the flux pinning characteristic in Bi-2212 bulk. A qualitative agreement between the experimental results and theoretical estimation was obtained.