A systematic study was made of the effect of sintering temperature on the phase formation, critical current density, upper critical field and irreversibility field of nanoscale SiC-doped MgB2. Bulk and Fe sheathed wires doped with different nano-SiC particle sizes were made and heat treated at temperatures ranging from 580 to 1000C. A systematic correlation between the sintering temperature, normal state resistivity, RRR, JC, HC2 and Hirr was found in all samples of each batch. Samples sintered at a lower temperature had a very fine and well consolidated grain structure, while samples sintered at high temperature contained large grains with easily distinguishable boundaries. Low-temperature sintering resulted in a higher concentration of impurity precipitates, larger resistivity, higher JC up to 15T and lower TC values. These samples exhibited higher HC2 and Hirr at temperatures near to TC but lower HC2 near T = 0 than samples sintered at high temperature. It was proposed that huge local strains produced by nano-precipitates and the grain boundary structure were the dominant mechanism responsible for higher HC2 at T near TC. However, higher impurity scattering due to C substitution was responsible for higher HC2 in the low-temperature regime for samples sintered at a higher temperature. In addition to high HC2, it was also proposed that the large number of nano-impurities serve as pinning centers and improve flux pinning, resulting in higher JC values at magnetic fields of up to 15T.

High Transport Critical Current Density and Large HC2 and Hirr in Nanoscale SiC Doped MgB2 Wires Sintered at Low Temperature. S.Soltanian, X.L.Wang, J.Horvat, S.X.Dou, M.D.Sumption, M.Bhatia, E.W.Collings, P.Munroe, M.Tomsic: Superconductor Science and Technology, 2005, 18, 658-66