Effects of the sintering temperature and doping of C 60 and SiC on the critical properties of MgB 2

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.%.