Bulk MgB2 was synthesized via the solid-state reaction of Mg and B at 600C. Its superconducting properties were compared with those of samples heated at 850C. The samples heated at 600C exhibited improved critical current properties in high fields at 20K. Poor crystallinity was found to contribute to the enhancement of HC2, Hirr and JC at high fields. On the other hand, the strongly grain connected network structure and smaller grain size were responsible for a high JC at low fields. An improved JC of up to 3.93 x 105A/cm2 and a high μ0Hirr of about 4.7T, as for undoped bulk MgB2, guaranteed that low-temperature sintering was a promising way to fabricate MgB2 conductors having a high critical current performance.

Improved Critical Current Properties Observed in MgB2 Bulks Synthesized by Low-Temperature Solid-State Reaction. A.Yamamoto, J.Shimoyama, S.Ueda, Y.Katsura, S.Horii, K.Kishio: Superconductor Science and Technology, 2005, 18, 116-21