Superconductivity of bulk MgB2 + nano(n)-SiC composite system: A high field magnetization study

TL;DR

This study investigates how adding nano-SiC to MgB2 enhances its superconducting properties, including critical temperature, current density, and flux pinning, especially under high magnetic fields, revealing potential for high-field applications.

Contribution

It demonstrates that nano-SiC addition improves MgB2's superconducting performance by increasing Tc, Jc, and flux pinning, with detailed structural and magnetic analysis.

Findings

Tc increases from 18.9K to 20.8K with 10 wt% n-SiC under 8 Tesla.

Irreversibility field (Hirr) is significantly enhanced in doped samples.

Critical current density (Jc) improves by factors of 20-35 with n-SiC addition.

Abstract

We study the effect of nano(n)-SiC addition on the crystal structure, critical temperature (Tc), critical current density (Jc) and flux pinning in MgB2 superconductor. X-ray diffraction patterns show that all the samples have MgB2 as the main phase with very small amount of MgO, further with n-SiC addition the presence of Mg2Si is also noted and confirmed by SEM & EDS. The Tc value for the pure MgB2 is 18.9K under 8 Tesla applied field, while is 20.8K for the 10-wt % n-SiC doped sample under the same field. This points towards the increment in upper-critical field value with n-SiC addition. The irreversibility field (Hirr) for the 5% n-SiC added sample reached 11.3, 10 and 5.8 Tesla, compared to 7.5, 6.5, and 4.2 Tesla for the pure MgB2 at 5, 10 and 20K respectively. The critical current density (Jc) for the 5-wt % n-SiC added sample is increased by a factor of 35 at 10K and 6.5 Tesla field and by a factor 20 at 20K and 4.2 Tesla field. These results are understood on the basis of superconducting condensate (sigma band) disorder and ensuing intrinsic pining due to B site C substitution clubbed with further external pinning due to available n-SiC/Mg2Si pins in the composite system.