Abstract
We investigated the effect of ZrSi2 and SiC doping on the microstructure, critical current densityJc and flux pinningof Fe-sheathed MgB2 tapes prepared by the in situ powder-in-tube method. Heat treatment was performed at a low temperatureof 650 °C for 1 h. The phases, microstructures and flux pinning were characterized by means of x-raydiffraction, scanning electron microscope, magnetic and transport property measurements. It wasfound that the tapes doped with nanoscale SiC had the best pinning performance, while theZrSi2 powder showed a similar improved field dependence ofJc compared withundoped samples. Jc values for the SiC doped samples were enhanced by two orders ofmagnitude at 4.2 K in magnetic fields above 8 T. At 4.2 K and 10 T, theJc reached ∼1.5 × 104 A cm−2. Moreover, the critical temperature for the doped tapes decreased slightly(<1.2 K). Microstructural analysis shows that very good grain connections or/and grainrefinement were obtained for the doped tapes. The mechanism of the enhancement of theflux pinning is also discussed.
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