Enhancement in the critical current density of C-doped MgB2 wire using a polyacrylic acid dopant.
C-doped MgB2 wires were fabricated from a polyacrylic acid (PAA) using a conventional in-situ PIT technique. The effects of the PAA content on the lattice parameter, microstructure, critical temperature (Tc) and critical current density (Jc) were examined. With increasing PAA content, the amount of MgO in the sample increased but the crystallinity, a-axis lattice parameter, and Tc of MgB2 wires decreased, indicating that the C that decomposed from PAA during heat treatment had substituted for B. All doped samples exhibited a higher Jc than the undoped sample at high magnetic field, and the Jc(B) property improved with increasing PAA content: for the 7 wt% doped sample, the Jc was approximately 3-times higher than that of the pristine sample (1.28 kA/cm2 vs. 3.43 kA/cm2) at 5 K and 6.6 T. The improved Jc(B) of the doped sample was attributed to the decreased grain size, enlarged lattice distortion and increased C doping level.
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea.
Seung Muk
SM
Lee
Soo Min
SM
Hwang
Chang Min
CM
Lee
Won
W
Kim
Jinho
J
Joo
Jun Hyung
JH
Lim
Chan-Joong
CJ
Kim
Gye-Won
GW
Hong