Superconducting Properties and Structure of In-Situ MgB2 Tapes With SiC and TiC Addition Prepared by Hot Pressing

In-situ powder-in-tube MgB₂ tapes have been prepared through a hot pressing process. Magnesium hydride MgH₂ and amorphous B powders were mixed to synthesize MgB₂ superconductor. The mixed powder was encased in a steel tube and rolled into a monocore tape of about 4 mm in width and 0.5 mm in thickness. Nano-sized SiC and TiC powders were added to the MgB₂ core. The tapes were hot-pressed under 100 MPa during the heat treatment in Ar gas atmosphere. The I_c for the hot-pressed tapes with 5 mass% SiC addition exceeds 300 A at 4.2 K and 5 T, which corresponds to a core J_c of nearly 1,000 A/mm². The core J_c is enhanced by more than a factor of two compared to that of tapes without pressing during the heat treatment. The higher J_c in hot pressed tapes results from the improvement of the denser MgB₂ structures with less voids and better linkage among MgB₂ grains.