The effect of ZrSi₂and SiC doping on the microstructure and<i>J</i>_c–<i>B</i>properties of PIT processed MgB₂tapes

Abstract

We investigated the effect of ZrSi2 and SiC doping on the microstructure, critical current density Jc and flux pinning of Fe-sheathed MgB2 tapes prepared by the in situ powder-in-tube method. Heat treatment was performed at a low temperature of 650 °C for 1 h. The phases, microstructures and flux pinning were characterized by means of x-ray diffraction, scanning electron microscope, magnetic and transport property measurements. It was found that the tapes doped with nanoscale SiC had the best pinning performance, while the ZrSi2 powder showed a similar improved field dependence of Jc compared with undoped samples. Jc values for the SiC doped samples were enhanced by two orders of magnitude at 4.2 K in magnetic fields above 8 T. At 4.2 K and 10 T, the Jc 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 grain refinement were obtained for the doped tapes. The mechanism of the enhancement of the flux pinning is also discussed.