Enhancement of in-field Jc in MgB2∕Fe wire using single- and multiwalled carbon nanotubes

Abstract

We investigated the doping effects of SWCNTs and MWCNTs on the T c , lattice parameters, J c (B), microstructure, and H c2 of MgB 2 /Fe wire. These effects systematically showed the following sequence for T c and the a-axis: the SWCNT doped wire < the MW short CNT doped wire < the MW long CNT doped wire < un-doped wire, while J c (B) followed the sequence of the SWCNT doped wire > the MW short CNT doped wire > the MW long CNT doped wire > un-doped wire. A dominating mechanism behind all these findings is the level of C substitution for B in the lattice. The best J c (B) and H c2 were obtained on SWCNT doped wire because the level of C substitution for B in this wire is higher than all others.

Carbon Nanotubes Addition Effects on MgB2 Superconducting Properties

“…Similarly to what was reported for bulk MgB 2 samples, they found that there is an optimum composition for all fields and temperatures studied, but the best composition for the nominal Mg(B 1-x C x ) 2 was x=0.05 and J c decreased for x = 0.10 (see Figure 9). However, many other researchers focused in which was considered the best composition x=0.10 studying the influence of other parameters: -the effect of CNT type (Kováč et al, 2007) in comparison with other C-compounds (SiC, graphite) -the effect of MWCNT size and sintering temperature (Kim et al, 2006a(Kim et al, , 2006b(Kim et al, , 2006c) -the effect of sintering temperature when using SW CNT (Kim et al, 2007) -the possibility of MW CNT alignment by mechanical drawing in the PIT process . .…”

“…. For comparison were included data from Fe/Nb sheath tapes with 5%wt addition of different CNT types (Kováč et al, 2007) and short and long MW CNT MgB 2 wires (Kim et al, 2006b) To illustrate the effect of some of the mentioned parameters we plotted in Figure 10 the critical current density of -Left side: MgB 2 /Fe-Nb tapes with 5%wt addition of different CNT types (Kováč et al, 2007). SW: Arc discharge single wall nanotubes; SW-D: Purified arc discharge single wall nanotubes, Dry-mixed; SW-W: Purified arc discharge single wall nanotubes, Wetmixed; MW: Multi wall carbon nanotubes (~60 nm × 1 μm).…”

Development of Doped ${\rm MgB}_{2}$ Wires and Tapes for Practical Applications

“…The J c -B performance can be greatly improvement by doping with various different carbon sources, such as nanocarbon [11,17], diamond [18], graphite [19], and carbon nanotubes [12].…”

“…Therefore, effects of such additives are being actively investigated, and some effective dopants have been suggested [2,3,[8][9][10][11][12][13][14][15]. The additions of SiC, nano-C, carbon nanotubes, B 4 C, as well as aromatic hydrocarbon and carbohydrate are effective to improve the J c -B characteristics of MgB 2 [2,3,[10][11][12][13][14][15]. When MgBB 2 is doped with these materials, C substitutes for B and introduces electron scattering and impurity scattering which reduce the mean free path and the coherence length ξ, hence increasing B c2 B [16].…”

Hollow carbon spheres as an efficient dopant for enhancing the critical current density of MgB2-based tapes

“…The J c of MgB 2 tapes can be easily exceeded the level 10 4 A/cm 2 at 4.2 K and 10 T through chemical doping with carbon containing materials, such as SiC [2][3][4], C [5,6], B 4 C [7], carbon nanotube [8,9], carbohydrate or hydrocarbon [10][11][12][13]. The carbon can be incorporated into the MgB 2 crystal lattice, and thus J c and H c2 are significantly enhanced due to the enhancement of charge carrier scattering in the two-band MgB 2 [14,15].…”