Negative effects of crystalline-SiC doping on the critical current density in Ti-sheathedMgB2(SiC)y superconducting wires

Abstract

Ti-sheathed MgB2 wires doped with nanosize crystalline-SiC up to a concentration of 15 wt% SiC havebeen fabricated, and the effects of the SiC doping on the critical current density(Jc) and other superconducting properties studied. In contrast with the previously reportedresults that nano-SiC doping with a doping range below 16 wt% usually enhancesJc, particularly at higher fields, our measurements show that SiC doping decreasesJc overalmost the whole field range from 0 to 7.3 T at all temperatures. Furthermore, it is found that the degradationof Jc becomes stronger at higher SiC doping levels, which is also in sharp contrast with the reported resultsthat Jc is usually optimized at doping levels near 10 wt% SiC. Our results indicate that these negative effectson Jc could be attributed to the absence of significant effective pinning centres (mainlyMg2Si) due to the high chemical stability of the crystalline-SiC particles.