Effect of aromatic hydrocarbon addition on in situ powder-in-tube processed MgB 2 tapes

Applied Physics Letters

et al. 2006

235

178

The effect of carbohydrate doping on lattice parameters, microstructure, Tc, Jc, Hirr, and Hc2 of MgB2 has been studied. In this work the authors used malic acid as an example of carbohydrates as an additive to MgB2. The advantages of carbohydrate doping include homogeneous mixing of precursor powders, avoidance of expansive nanoadditives, production of highly reactive C, and significant enhancement in Jc, Hirr, and Hc2 of MgB2, compared to undoped samples. The Jc for MgB2+30wt% C4H6O5 sample was increased by a factor of 21 at 5K and 8T without degradation of self-field Jc.

mentioning

confidence: 55%

Carbohydrate doping to enhance electromagnetic properties of MgB2 superconductors

Kim

Zhou

Applied Physics Letters

et al. 2006

235

178

“…The research toward improvement of j c properties in MgB 2 has been mostly aimed at enhancing the H irr , the flux pinning ability, and H c2 by irradiation or chemical doping. [2][3][4][5][6][7][8] Chemical doping has been proved to be a simple and effective way to introduce pinning centers into MgB 2 superconductor or to improve the upper critical field. It is believed that carbon containing dopants, such as nano-SiC, 5 carbon nanotubes, 6 nanocarbon, 7 hydrocarbons, 8 silicone oil, 9,10 malic acid, 11 etc., are especially effective in enhancing the H c2 , and hence the j c properties of MgB 2 in high magnetic fields.…”

Section: Introductionmentioning

confidence: 99%

“…19 such as silicone oil and other oxide or nonoxide nanomaterials. [5][6][7][8][9][10][11]19,20 Improvement of the j c ͑B͒ was quite successful for most of chemical doped MgB 2 . However, the origin of the pinning mechanisms are still not well understood except the silicon oil doped case.…”

Section: Introductionmentioning

confidence: 99%

Strong competition between the δl and δTc flux pinning mechanisms in MgB2 doped with carbon containing compounds

Ghorbani

Wang

Journal of Applied Physics

et al. 2010

The transport and magnetic properties of 10 wt % malic acid and 5 wt % nanocarbon doped MgB2 have been studied by measuring the resistivity (ρ), critical current density (jc), connectivity factor (AF), irreversibility field (Hirr), and upper critical field (Hc2). The pinning mechanisms are studied in terms of the collective pinning model. It was found that both mean free path (δl) and critical temperature (δTc) pinning mechanisms coexist in both doped MgB2. For both the malic acid and nanocarbon doped samples, the temperature dependence of the crossover field, which separates the single vortex and the small bundle pinning regime, Bsb(T), shows that the δl pinning mechanism is dominant for temperatures up to t(T/Tc)=0.7 but the δTc pinning mechanism is dominant for t>0.7. This tendency of coexistence of the δl and the δTc pinning mechanism is in strong contrast with the pure MgB2, in which the δTc pinning mechanism is dominant over a wide temperature range below Tc. It was also observed that the connectivity factor, active cross-sectional area fraction (AF), are 0.11 and 0.14 for the nanocarbon and the malic acid doped MgB2, respectively, indicating that there are still rooms for further improving jc performance.

“…Although Yamada et al 14 prepared Fe sheathed tape samples by using a liquid aromatic hydrocarbon together with ball milling, it is very difficult to control the composition during ball milling because of its volatile properties. In this study, therefore, we suggested a different hydrocarbon, pyrene ͑C 16 H 10 ͒, which has no oxygen content, as the C source.…”

mentioning

confidence: 99%

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

Kim

Applied Physics Letters

et al. 2008

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.