Effect of processing temperature on high field critical current density and upper critical field of nanocarbon doped MgB2

Yeoh, Wai Kong; Horvat, J.; Kim, Jung Ho; Xu, Xiaojing; Dou, Shi Xue

doi:10.1063/1.2715026

Cited by 43 publications

(38 citation statements)

References 34 publications

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“…Soon thereafter, our results have been confirmed by many groups worldwide [22][23][24]. The addition of nano-C causes substitution of boron by carbon, which decreases the critical temperature and increases the upper critical field as well as the current density in high magnetic fields.…”

Section: Carbon Dopingsupporting

confidence: 83%

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

Gao

Wang

et al. 2010

IEEE Trans. Appl. Supercond.

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Abstract-A review of current developments in the study of chemical doping effect on the superconducting properties of MgB 2 wires and tapes is presented, based on the known literature data and our own results. The critical current density of MgB 2 can be improved through various kinds of dopants. Among these dopants, doping with carbon-containing materials seems to be the most effective way to improve the J c performance. The doping effect of carbon in different forms and carbon-based compounds such as SiC, nano-C, metal carbides, as well as aromatic hydrocarbon and carbohydrate on the J c -B characteristics of MgB 2 was discussed in detail. The C can be incorporated into the MgB 2 crystal lattice by replacing boron, and thus BB c2 is significantly enhanced due to selective tuning of impurity scattering of the π and σ bands in the two-band MgB 2 . Besides the efforts of increasing B c2 B by carbon doping, the fine grain size and nano-size inclusions caused by doping would create many flux pinning centres improving the J c -B property of MgB 2 . Based on these considerations, we suggested some principles for the selection of dopants.

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Section: Carbon Dopingsupporting

confidence: 83%

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

Gao

Wang

et al. 2010

IEEE Trans. Appl. Supercond.

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“…17,18 To confirm the physical mechanism of the J c ͑H͒ variation and the origin of the flux pinning force, F p =−J c H, with different sintering temperatures, Raman scattering measurements were employed in this study. Raman scattering has the benefits of excellent energy resolution, a relatively large penetration depth, the ability to selectively measure different portions of the Fermi surface͑s͒, 19 and, especially in superconductors, the benefit of revealing both the existence of the superconducting gap and its strong coupling to some of the active Raman phonons.…”

Section: Introductionmentioning

confidence: 99%

Raman study on the effects of sintering temperature on the Jc(H) performance of MgB2 superconductor

Chen

et al. 2008

Journal of Applied Physics

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The influence of sintering temperature on the critical transition temperature T c and critical current density J c for the MgB 2 superconductor was investigated systematically with the observation of Raman scattering measurement and flux pinning force F p analysis. The enhanced E 2g mode in Raman spectra with increasing in situ sintering temperature shows gradual strengthening of the electron-phonon coupling in MgB 2 , which means that the crystals become more harmonic after higher temperature sintering. However, the crystal harmonicity is degraded for samples sintered at even higher temperature due to Mg deficiency. A possible explanation for the J c ͑H͒ performance, which is in accordance with the Raman spectroscopy observation and F p analysis, is the cooperation between the electron-phonon coupling in the E 2g mode and the flux pinning centers, mainly originating from the lattice distortion due to the different sintering temperatures.

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“…The study of reaction kinetics for different carbonaceous chemicals during the MgB 2 synthesis is a crucial issue for understanding the H irr , H c2 , and J c performance in MgB 2 . A systematic correlation between the processing temperature, J c , and H c2 has been observed in pure, nano-carbon, CNT, SiC, and hydrocarbon doped MgB 2 samples Yeoh et al, 2007b). The processing temperature is believed to be the most important factor influencing the electromagnetic properties because both the carbon substitution intensity and the microstructure are dependent on it.…”

Section: Mechanism Of Doping Effects -Dual Reaction Modelmentioning

confidence: 95%