Journal of Powder Materials

Soon-Dong Park

5 Articles

Synthesis of YBa₂Cu₃O_7-y Powder using a Powder Reaction Method and Fabrication of the Bulk Superconductors: Young Ju Jeon, Seung Yeon Park, Byung Youn You, Soon-Dong Park, Chan-Joong Kim; J Powder Mater. 2013;20(2):142-147.; DOI: https://doi.org/10.4150/KPMI.2013.20.2.142

Abstract PDF: YBa_2Cu_3O_7-y (Y123) powders for the fabrication of bulk superconductors were synthesized by the powder reaction method using Y_2O_3 (99.9% purity), BaCO_3 (99.75%) and CuO (99.9%) powders. The raw powders were weighed to the cation ratio of Y:Ba:Cu=1:2:3, mixed and calcined at 880°C-930°C in air with intermediate repeated crushing steps. It was found that the formation of Y123 powder was more sensitive to reaction temperature than reaction time. The calcined Y123 powder and a mixture of (Y123 + 0.25 mole Y_2O_3 + 1 wt.% CeO_2, Y_1.5Ba_2Cu_3O_x (Y1.5)) were used as raw powders for the fabrication of poly-grain or single grain superconductors. The superconducting transition temperature (T_c,onset) of the sintered Y123 sample was 91 K and the transition width was as large as 11 K, whereas the T_c,onset of the melt-grown Y1.5 sample was 90.5 K and the transition width was 3.5 K. The critical current density (J_c) at 77 K and 0 T of the sintered Y123 was 700 A/cm2, whereas the J_c of the top-seeded melt growth (TSMG) processed Y1.5 sample was 3.2times104;A/cm2. The magnetic flux density (H) at 77 K of the TSMG-processed Y123 and Y1.5 sample showed the 0.53 kG and 2.45 kG, respectively, which are 15% and 71% of the applied magnetic field of 3.5 kG. The high H value of the TSMG-processed Y1.5 sample is attributed to the formation of the larger superconducting grain with fine Y211 dispersion.

Effects of Nano Fe_xC Addition on Superconducting Properties of MgB₂: Dong-Gun Lee, Ji-Hyun Lee, Byung-Hyuk Jun, Soon-Dong Park, Young-Rang Uhm, Hai-Woong Park, Chan-Joong Kim; J Korean Powder Metall Inst. 2012;19(2):146-150.; DOI: https://doi.org/10.4150/KPMI.2012.19.2.146

Abstract PDF: The effects of nano Fe_xC addition to superconducting properties of in situ processed MgB_2 superconductors was examined. 0.1 wt.% and 1 wt.% nano Fe_xC powders were mixed with boron and magnesium powders by ball milling. The powder mixtures were made into pellets by uniaxial pressing. The pellets were heat-treated at 700°C-900°C in argon atmosphere for MgB_2 formation. It was found by powder X-ray diffraction that the raw powders were completely converted into MgB_2 after the heat treatment. The superconducting transition temperature (T_c) and critical current density (J_c), estimated from susceptibility-temperature and M-H curves, were decreased by nano Fe_xC addition. The T_c and J_c decrease by nano Fe_xC addition are attributed to the incorporation of iron and carbon with MgB_2 lattices (Fe substitution for Mg and C substitution for B) due to the high reactivity of the nano Fe_xC powder.

Estimation of a Lattice Parameter of Sintered Ni-W Alloy Rods by a Neutron Diffraction Method: Chan-Joong Kim, Min-Woon Kim, Soon-Dong Park, Byung-Hyuk Jun, Serk-Won Jang, Baek-Seok Seong; J Korean Powder Metall Inst. 2008;15(3):239-243.; DOI: https://doi.org/10.4150/KPMI.2008.15.3.239

Abstract PDF: Ni-W(1-5 at.%) alloy rods were made by powder metallurgy process including powder mixing, compacting and subsequent sintering. Ni and W powder of appropriate compositions were mixed by a ball milling and isostatically pressed in a rubber mold into a rod. The compacted rods were sintered at 1000°C-1150°C at a reduced atmosphere for densification. The lattice parameters of Ni-W alloys were estimated by a high resolution neutron powder diffractometer. All sintered rods were found to have a face centered cubic structure without any impurity phase, but the diffraction peak locations were linearly shifted with increasing W content. The lattice parameter of a pure Ni rod was 3.5238AA which is consistent with the value reported in JCPDS data. The lattice parameter of N-W alloy rods increased by 0.004AA for 1 atomic % of W, which indicates the formation of a Ni-W solid solution due to the substitution of nickel atoms by tungsten atoms of larger size.

Superconducting Properties of Mg(B_1-xC_x)₂ Bulk Synthesized Using Magnesium and Glycerin-treated Boron Powder: Yi-Jeong Kim, Byung-Hyuk Jun, Soon-Dong Park, Kai Sin Tan, Bong-Goo Kim, Jae-Min Sohn, Chan-Joong Kim; J Korean Powder Metall Inst. 2008;15(3):182-187.; DOI: https://doi.org/10.4150/KPMI.2008.15.3.182

Abstract PDF: Carbon was known to be one of effective additives which can improve the flux pinning of MgB_2 at high magnetic fields. In this study, glycerin (C_3H_8O_3) was selected as a chemical carbon source for the improvement of critical current density of MgB_2. In order to replace some of boron atoms by carbon atoms, the boron powder was heat-treated with liquid glycerin. The glycerin-treated boron powder was mixed with an appropriate amount of magnesium powder to MgB_2 composition and the powder pallets were heat treated at 650°C;and;900°C for 30 min in a flowing argon gas. It was found that the superconducting transition temperature (T_c) of Mg(B_1-xC_x)_2 prepared using glycerin-treated boron powder was 36.6 K, which is slightly smaller than T_c(37.1 K) of undoped MgB_2. The critical current density (J_c) of Mg(B_1-xC_x)_2 was higher than that of undoped MgB_2 and the T_c improvement effect was more remarkable at higher magnetic fields. The T_c, decrease and J_c increase associated with the glycerin treatment for boron powder was explained in terms of the carbon substitution to boron site.

Synthesis of Yba₂Cu₃O_7-y Superconductor using a Low Purity BaCO₃ Powder: Chan-Joong Kim, Soon-Dong Park, Jung-Suk Choi, Byung-Hyuk Jun, Jong-Baik Moon, Sang-Heon Lee, Tae-Hyun Sung; J Korean Powder Metall Inst. 2008;15(1):6-12.; DOI: https://doi.org/10.4150/KPMI.2008.15.1.006

Abstract PDF: [ YBa_2Cu_3O_7-y ](123) powders were synthesized by the solid state reaction method using two different purity BaCO_3 powders (99.75% and 99.7% purity) and Y_2O_3 (99.9%) and CuO (99.9%) powders. The effect of BaCO_3 purity on the formation of a 123 phase and the superconducting properties were investigated. The mixtures of raw powders were calcined at temperature ranges of 800°C-880°C in air and finally made into a single grain samples by a melt processing with top seeding. It was found that a 123 phase was well formed at temperature above 870°C, but the purity effect on the 123 formation was negligible. The single-grain 123 samples prepared from the different BaCO_3 powders showed the same T_c value of 90.5 K and similar J_c values about 104;A/cm2 at 0 T and 77 K, and 103;A/cm2 at 2 T and 77 K. This result indicates that the low purity, cheap price BaCO_3 powder can be used as a raw material for the fabrication of single-grain, high-J_c superconducting levitator.

Author index