Carbon nanotubes effects on the relaxation properties and critical current densities of MgB2 superconductor

Abstract

Addition of nonsuperconducting phases, such as carbon nanotubes, can modify the superconducting properties of MgB 2 samples, improving the critical current density and upper critical field. A full understanding of the flux creep mechanism involved is crucial to the development of superconducting magnets in persistent mode, one of the main thrusts for the development of MgB 2 wires. In this paper we present a creep study in bulk MgB 2 samples, pure and with different amounts of carbon nanotubes additions. We conclude that the most consistent picture at low temperatures is a single vortex pinning regime, where the correlation length is limited by the grain size. We introduce a novel analysis that allows us to identify the region where the Anderson-Kim model is valid. V C 2013 AIP Publishing LLC. [http://dx

Effect of cubic and hexagonal boron nitride additions on the microstructure and properties of bulk MgB2 superconductors

“…Some impurity atoms with a radius comparable to Mg or B atoms can substitute into the MgB 2 lattice, creating strain and disorder. Carbon doping is a good example, and the addition of many different carbon sources have been reported, including carbon nanoparticles [8], carbon nanotubes [9] and even organic matter [10]. C substitution for B in the MgB 2 lattice increases the intra-band scattering, resulting in reduced anisotropy and higher H c2 values in C-doped MgB 2 samples [11,12].…”