G Liang et al 2007 Supercond. Sci. Technol. 20 697 doi:10.1088/0953-2048/20/7/019
G Liang1,6, H Fang1, Z P Luo2, C Hoyt1, F Yen3, S Guchhait4, B Lv5 and J T Markert4
Show affiliationsTi-sheathed MgB2 wires doped with nanosize crystalline-SiC up to a concentration of 15 wt% SiC have been fabricated, and the effects of the SiC doping on the critical current density (Jc) and other superconducting properties studied. In contrast with the previously reported results that nano-SiC doping with a doping range below 16 wt% usually enhances Jc, particularly at higher fields, our measurements show that SiC doping decreases Jc over almost the whole field range from 0 to 7.3 T at all temperatures. Furthermore, it is found that the degradation of Jc becomes stronger at higher SiC doping levels, which is also in sharp contrast with the reported results that Jc is usually optimized at doping levels near 10 wt% SiC. Our results indicate that these negative effects on Jc could be attributed to the absence of significant effective pinning centres (mainly Mg2Si) due to the high chemical stability of the crystalline-SiC particles.
84.71.Mn Superconducting wires, fibers, and tapes
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
Issue 7 (July 2007)
Received 10 April 2007, in final form 6 May 2007
Published 4 June 2007
G Liang et al 2007 Supercond. Sci. Technol. 20 697
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