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Superconductivity of the bulk MgB2 + nano(n)-SiC composite system: a high field magnetization study

Vajpayee, Arpita and Awana, V. P. S. and Bhalla, G. L. and Kishan, H. (2008) Superconductivity of the bulk MgB2 + nano(n)-SiC composite system: a high field magnetization study. NANOTECHNOLOGY, 19 (12).

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Official URL: http://www.iop.org/EJ/abstract/0957-4484/19/12/125...

Abstract

We study the effect of nano(n)-SiC addition on the crystal structure, critical temperature (T-c), critical current density (J(c)) and flux pinning in MgB2 superconductors. X-ray diffraction patterns show that all the samples have MgB2 as the main phase with a very small amount of MgO; further, with n-SiC addition the presence of Mg2Si is also noted and confirmed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The Tc value for pure MgB2 is 18.9 K under 8 T applied field, while it is 20.8 K for the 10 wt% n-SiC doped sample under the same field. This points towards the increment in the upper critical field value with n-SiC addition. The irreversibility field (H-irr) for the 5% n-SiC added sample reached 11.3, 10 and 5.8 T, compared to 7.5, 6.5, and 4.2 T for the pure MgB2 at 5, 10 and 20 K, respectively. The critical current density (J(c)) for the 5 wt% n-SiC added sample is increased by a factor of 35 at 10 K and 6.5 T field and by a factor 20 at 20 K and 4.2 T field. These results are understood on the basis of superconducting condensate (sigma band) disorder and ensuing intrinsic pining due to B-site C substitution clubbed with further external pinning due to available n-SiC/Mg2Si pins in the composite system.

Item Type:Article
Subjects:Analytical Science > Microscopy and probe methods
Physical Science > Nanophysics
Engineering > Nanotechnology applications in ICT
ID Code:6270
Deposited By:IoN
Deposited On:22 Dec 2009 11:56
Last Modified:22 Dec 2009 11:56

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