Effects of the sintering temperature and doping of C60 and SiC on the critical properties of MgB2

Abstract We fabricated MgB 2 using the powder-in-tube (PIT) method with the in situ route and evaluated the effects of the sintering temperature and doping of fullerene (C 60 ) and SiC on the critical properties. It was found that a sintering temperature in the range of 650–750 °C was more effective in maintaining good J c vs. H behavior than a sintering temperature of 900 °C, which is probably due to the resultant poorer crystallinity and smaller grain size, which provide more grain boundary that act as flux pinning center. In addition, we selected C 60 as a new dopant, because it has a low decomposition temperature (about 280 °C), and compared the doping effect of C 60 to that of SiC. It was observed that the wire doped with 10 wt.% of C 60 had a J c value of as high as 1.60 × 10 4  A/cm 2 at 5 T and 5 K, which was comparable to that of the J c of 5 wt.% SiC doped wire (1.64 × 10 4  A/cm 2 ). On the other hand, the C 60 doped wire did not degrade the T c distinguishably with increasing C 60 content to 10 wt.%.