Fabrication and superconducting properties of nano-SiC doped MgB2 tapes

Nano-SiC doped MgB₂ tapes were prepared by the in situ powder-in-tube method. Heat treatment was performed at 650°C for 1 h. XRD data indicate that SiC particles had reacted with the MgB₂ during sintering process. MgB₂ core seemed to be denser after SiC doping, and the critical temperature was slightly depressed. The critical current density J _c of the SiC doped tapes was significantly enhanced in magnetic fields up to 14 T compared to the undoped ones. For the 5% SiC doped samples, J _c was increased by a factor of 32 at 4.2 K, 10 T. The enhancement of J _c-B properties in SiC doped MgB₂ tapes is considered to be due to the enhancement of grain linkages and the introduction of effective flux pining centers. The substitution of B by C in MgB₂ grains is thought to be the main reason for the improvement of the flux pinning ability in SiC doped MgB₂ tapes. Supported by the National Natural Science Foundation of China (Grant Nos. 50472063 and 50377040) and the State Key Development Program for Basic Research Program of China (Grant No. 2006CB601004)