Yeung Soon Park

Publications (2)2.22 Total impact

• Article: Improvement of the critical current density and upper critical field in C-doped MgB2 wire using cellulose acetate

  Soo Min Hwang, Chang Min Lee, Won Kim, Geun Chul Park, Jinho Joo, Jun Hyung Lim, Won Nam Kang, Yeung Soon Park, Dong Ho Kim
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  ABSTRACT: We fabricated carbon-doped MgB2 wires by an in-situ reaction route using cellulose acetate (CA) as an organic dopant in order to investigate the correlation between the critical properties and the CA doping level based on the phase formation and lattice changes. The starting B powder was uniformly mixed with 0 wt.% to 7 wt.% CA powders by a liquid mixing technique. The precursor powders were mixed with Mg powder and loaded into Fe tubes, which were drawn into wires and then sintered at 900 °C for 1 h under an Ar atmosphere. The CA doping reduced the critical temperature (Tc), but improved the critical current density (Jc) in the magnetic field, upper critical field (Hc2), and irreversibility field (Hirr). These effects were attributed to the CA doping-induced substitution of C for the B sites, which consequently increased the flux pinning force and the charge-carrier scattering. The Jc value of the MgB2 wire doped with 7 wt.% CA was improved by a factor of 31 (3.46 kA/cm2) as compared with that of the pure wire (0.11 kA/cm2) at 5 K and 6.6 T. This increase suggests that the CA doping via the liquid mixing is an effective way to improve the Jc(B) and Hc2 of MgB2 wire. Keywordsdrawing–magnetic properties–microstructure–superconductors–transmission electron microscopy (TEM)
  Metals and Materials International 04/2012; 16(6):1029-1033. · 1.18 Impact Factor
• Article: Enhanced Magnetic Property of MgB Wire Using Phenol-Formaldehyde Resin

  Chang Min Lee, Soo Min Hwang, Kisoo Sung, Seung Muk Lee, Jinho Joo, Won Nam Kang, Jun Hyung Lim, Chan-Joong Kim, Yeung Soon Park, Dong Ho Kim
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  ABSTRACT: Abstract-We fabricated carbon (C)-doped MgB₂ wires using phenol-formaldehyde resin (PF) as a C source to improve their critical current density (J_c) in a magnetic field. In order to induce homogenous C doping, boron (B) powders were mixed with PF via liquid mixing technique and then the PF-treated B and Mg powders were mixed. The wires were fabricated by conventional powder-in-tube (PIT) process, followed by heat treatment through an in-situ reaction route. We observed that C was substituted for the B sites in the PF-doped MgB₂ and that the actual C content increased with increasing PF content. The doped MgB₂ wires exhibited lower critical transition temperature (T_c ) and self-field J_c, but superior H_c2 value and better J_c(B) performance than the undoped sample. The 3 wt% PF sample had the highest J_c value of 7.77 ?? 10³ A/cm , which is significantly higher than that of the undoped sample (0.29 ?? 10³ A/cm²) at 5 K and 6.4 T.
  IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor