Influence of disorder on the in-field Jc of MgB2 wires using highly active pyrene

Abstract

In this work, we report on significantly enhanced critical current density (Jc) in MgB2 superconductor that was easily obtained by doping with a hydrocarbon, highly active pyrene (C16H10), and using a sintering temperature as low as ∼600°C. The processing advantages of the C16H10 additive include production of a highly active carbon (C) source, an increased level of disorder, and the introduction of small grain size, resulting in enhancement of Jc.

Superconducting properties of MgB2 prepared from attrition ball-milled boron powder

“…6 shows the magnetic field dependence of J c for all samples at 5 K and 20 K. The highest J c , ∼70,000 A/cm 2 at 5 K and 4 T, was obtained for the sample using boron that was ball milled for 5 h. This J c value is much higher than sample prepared by the reference boron, but similar to that of the sample using amorphous boron [11]. This is mainly due to smaller grain size and higher lattice distortion [12,29]. It is well known that small grain size might be effective for enhancing flux pinning, because the grain boundaries represent effective pinning centers [26,30].…”

“…So far, many groups have reported the improvement of J c through doping with various carbon (C) compounds such as SiC [4][5][6][7], C [8][9][10], and organic compounds (carbohydrate and hydrocarbon) [11][12][13], but the achievements from this were less than might be expected because of decreased superconducting volume, degradation of connectivity, and agglomeration of doping materials. Specifically, most efforts have been made to introduce dopants into the MgB 2 structure to elucidate how to change the crystal structure, as well as how to improve the superconducting properties.…”

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

“…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, with sintering at either low temperature or high temperature in previous studies [23][24][25][26][27][28][29].…”

“…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 solid-solid reaction between Mg and B can lead to the effective carbon substitution for B during the low-temperature synthesis.…”

Enhanced critical current properties of in situ processed MgB2 wires using milled boron powder and low temperature solid-state reaction

“…Besides, the lower cost of the starting materials of magnesium (Mg) and boron (B) powders compared to Nb-Ti or Nb 3 Sn is also an additional benefit for practical applications. Many attempts have been conducted to fabricate this material with the aim of improving its superconducting properties under high magnetic fields through a doping with various forms of carbon (C) such as SiC, C compounds, carbohydrate and hydrocarbon [1][2][3][4][5][6][7][8][9]. However, processing pure MgB 2 samples with good quality is equally important and costeffective without the use of dopants.…”