Improved Transport J c in MgB2 Tapes by Graphene Doping

Abstract

Graphene is a special form of carbon which can effectively enhance the critical current density J c of MgB 2 . In this work, a systematic investigation on the impact of sintering conditions and doping level was carried out for graphene-doped MgB 2 tapes. It is found that an appropriate addition level, i.e., 8 at% in this work, is very critical to obtain a high J c in graphene-doped samples. The critical field and pinning force are improved obviously due to the graphene doping. The magnetic J c of samples sintered at 800 • C with 8 at% graphene doping reached 1.78 × 10 4 A/cm 2 , at 5 T, 20 K. At the same time, the transport J c was up to 2.38 ×10 4 A/cm 2 at 10 T, 4.2 K. The lattice distortion caused by C substitution and residual C at the grain boundaries were thought to be the major factors affecting the J c of graphene-doped MgB 2 samples.

Significantly enhanced critical current density in nano-MgB2grains rapidly formed at low temperature with homogeneous carbon doping

“…Combining thermal analysis of the synthesis process, phase composition identification, detailed microstructure observations, and superconducting properties measurements, it was found that dense nano-MgB 2 grains with a high level of homogeneous carbon doping were formed in these MgB2 samples, using carbon-coated boron as a precursor that was prepared by Cu-activated sintering at low temperature. This synthesis method is responsible for the significantly improved J c of the present samples compared to MgB 2 samples chemically doped with nano-SiC and other carbon-based dopants and with sintering at either low temperature or high temperature in previous studies [23][24][25][26][27][28][29].…”

“…Evidently, choosing the appropriate approaches that can effectively introduce carbon doping during low-temperature sintering is fundamental to the successful application of this method. Based on previous studies [2,[24][25][26][27][28], not all carbon doping techniques that are effective in the high-temperature synthesis process of MgB 2 are still available in their low-temperature synthesis process. It is proposed that only those approaches that are able to release highly active C before the commencement of a solidsolid reaction between Mg and B can lead to effective carbon substitution for B during the low-temperature synthesis.…”

Flux-Pinning Effects and Mechanism of Water-Quenched 5 wt.% (Fe, Ti) Particle-Doped MgB2 Superconductor

“…On the other hand, there were several reports that diamagnetic property and critical current (J c ) were changed according to dopant level [4][5][6][7][8]. However, detailed mechanism and the cause have been not shown.…”

An Improved Smart Meta-Superconductor MgB2

“…Chemical doping is the simplest method to change JC of superconductor. Doping graphene in MgB2 [31], and Al2O3 [32] and MgO [33] in BiSrCaCuO will reduce JC under zero magnetic field. The same time, adding anthracene into MgB2 [34] and Cr2O3 into BiSrCaCuO [35] will increase JC under zero magnetic field.…”