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

Authors

W. K. Yeoh, University of Wollongong
J. Horvat, University of WollongongFollow
J. H. Kim, University of WollongongFollow
X. Xu, University of Wollongong
S. X. Dou, University of WollongongFollow

RIS ID

19954

Publication Details

This article was originally published as Yeoh, WK, Horvat, J, Kim, JH, Xu, X and Dou, SX, Effect of processing temperature on high field critical current density and upper critical field of nanocarbon doped MgB2, Applied Physics Letters, 90(12), 2007, 122502-1-122502-3. Copyright American Institute of Physics 2007. Original journal article available here

Abstract

Correlation of upper critical field (H_c2) and critical current density (J_c) with processing temperature of nano-C doped MgB₂ has been studied in comparison to SiC and pure MgB₂. SiC and C doped MgB₂ exhibit opposite trends in the dependence of J_c and H_c2 on sintering temperature. This is explained by different reactivities of carbon available upon creation of MgB₂ for the two types of doping. Nanocarbon doped MgB₂ requires sintering temperatures in excess of 900 °C to obtain high boron substitution for carbon, enhancing the vortex pinning and impurity scattering of charge carriers. However, carbon substitution in nano-SiC doped MgB₂ occurs at less than 650 °C, allowing lower sintering temperature and high degree of carbon substitution. Both pure and SiC doped MgB₂ benefit from low sintering temperature, which results in more grain boundary defects. Substantial carbon substitution can compensate for the disadvantage of sintering at high temperature of nano-C doped MgB₂, giving the best J_c of 4.8x10³ A/cm² at 4.5 K and 12 T. This is comparable to the low-temperature sintered nano-SiC doped MgB₂ wires.

Grant Number

ARC/DP0770205

Additional Grant Number

http://purl.org/au-research/grants/ARC/DP0770205