Effect of carbon nanotube doping on critical current density of MgB2 superconductor

TL;DR

Doping MgB2 with carbon nanotubes enhances its critical current density and flux pinning capabilities in magnetic fields, though it reduces the transition temperature, with optimal doping levels achieving significant performance improvements.

Contribution

This study demonstrates how controlled carbon nanotube doping improves MgB2 superconductor performance, balancing increased critical current density with minimal Tc reduction.

Findings

Jc increased by two orders of magnitude at high fields and low temperatures

Optimal doping enhances flux pinning and critical current density

Tc decreases with increased doping and sintering conditions

Abstract

The effect of doping MgB2 with carbon nanotubes on transition temperature, lattice parameters, critical current density and flux pinning was studied for MgB2-xCx with x = 0, 0.05, 0.1, 0.2 and 0.3. The carbon substitution for B was found to enhance Jc in magnetic fields but depress Tc. The depression of Tc, which is caused by the carbon substitution for B, increases with increasing doping level, sintering temperature and duration. By controlling the extent of the substitution and addition of carbon nanotubes we can achieve the optimal improvement on critical current density and flux pinning in magnetic fields while maintaining the minimum reduction in Tc. Under these conditions, Jc was enhanced by two orders of magnitude at 8T and 5K and 7T and 10K. Jc was more than 10,000A/cm2 at 20K and 4T and 5K and 8.5T, respectively.