• 한국결정성장학회지
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• 제21권5호
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• pp.199-204
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• 2011

존멜팅법을 이용해서 $(YSmNd)_{1.8}Ba_{2.4}Cu_{3.4}O_{7-x}$계 고온초전도체를 대기 중에서 용융성장실험을 하였다. 존멜팅법의 최적용융온도는 $1100^{\circ}C$였으며 성장속도는 3.5 mm/h 였다. 한 방향으로 용융성장 된 (YSN)1.8 초전도체는 XRD, 광학현미경, TEM을 이용하여 미세구조를 관찰하였으며 SQUID magnetometer와 직접전류수송법을 이용해 초전도특성을 평가하였다. 특히 용융성장 된 (YSN)1.8 초전도체의 광학현미경에 의한 미세구조 관측 결과 초전도상인 (YSN)123 matrix내에 비초전도상인 (YSN)211 inclusions이 균질하게 분포되어 있는 것이 관측되었다. 또한 용융성장 된 (YSN)1.8 초전도체는 90 K 이상의 임계온도 특성을 보였으며 액체질소 안에서 직접전류수송법으로 측정한 결과 수송전류 830 A에서 $3.93{\times}10^4$(A/$cm^2$)를 갖는 높은 임계전류밀도 특성을 보였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1992년도 추계학술발표강연 및 논문개요집
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• pp.16-16
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• 1992

We have studied the effect of platinum addition on the supercon ducting properties of YB $a_2$C $u_3$$O_{7-x}$ (123) compound and elucidated the mechanism of fine dispersion of $Y_2$BaCu $O_{5}$(211) particles in YB $a_2$C $u_3$$O_{7-x}$ superconductor prepared by melting method from the metallurgical point of view. In this study, BaCu $O_2$ and CuO-rich phase unreacted during the peritecitc reaction markedly decreased by the 211 powder addition. The 211 particle of Pt-fee sintered samples exhibited 8~10$\mu$m in size, but in 1wt%Pt-added sample, 211 particles were finely dispersed in 123 matrix and the size of 211 particle was about 1~2$\mu$m. And, the critical temperature( $T_{c. zero}$) of Pt doped samples was 91.5K and the transport critical current density ( $J_{c}$) of Pt-doped samples was much more than 10$^4$A/$\textrm{cm}^2$. The high $J_{c}$ and fine dispersion of 211 particles of Pt doped YB $a_2$C $u_3$$O_{7-x}$ superconductor are attributed to $Ba_4$CuP $t_2$ $O_{8}$ compounds formed during the partial melting, which were considered als nucleation sites of 211 particles, rather than Pt inself.han Pt inself.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.14-16
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• 2002

Melting and re-solidification nature of $SmBa_2Cu_3O_{7-y}$ (Sm123) grains in Ba-Cu-O (Ba:Cu=3:5) liquid containing 0.7 at.% yttrium were investigated at the temperature lower than its melt point. When Sm123 grains/liquid powder compacts were heated to a temperature between two melting points of Ba-Cu-O liquid ($1000^{\circ}C$) and a Sm123 phase ($1060^{\circ}C$) and held at this temperature for appropriate time, Sm123 grains melted partly in the liquid that was formed by melting of the liquid-forming powder. During subsequent slow cooling, (Sm,Y)$Ba_2Cu_3O_{7-y}$ solidified at the outer parts of the unmelted Sm12 grains, which is distinguished from the core regions by lower $Sm_2BaCuO_5$ (211) density.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1992년도 춘계학술발표회
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• pp.86-87
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• 1992

• 한국전기전자재료학회논문지
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• 제36권1호
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• pp.70-73
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• 2023

To improve superconductor properties, the size of the crystal grains of the superconductor should be adjusted, the amount of electricity flowing through the superconductor should be increased, and the superconductor should be designed to withstand external magnetic fields. It is necessary to control the microstructure so that many flux pinning centers are developed inside the superconductor so that defects are generated physically or chemically, and the micro secondary phase for trapped magnetic flux must be dispersed inside the superconductor. In order to measure the superconducting magnetic force of the superconducting bulk in a simplified manner, the superconducting magnetic force was analyzed using an Nd-Fe-B permanent magnet of 3.80 kG. In particular, by delaying the growth of partially melted Y₂BaCuO₅ particles, we devised a plan to refine Y₂BaCuO₅ particles to effectively improve superconducting magnetic force, and analyzed superconducting magnetic force in a single crystal YBa₂Cu₃O_7-y superconducting bulk using a gauss meter. The melted superconducting bulk traps 80% or more of the applied magnetic field, and can be used as a bulk magnet of high magnetic field magnetization applicable to electric power equipment.

• Bulletin of the Korean Chemical Society
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• 제10권1호
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• pp.5-8
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• 1989

Conventional ceramic method has been used to prepare the green phase, $Y_2BaCuO_5$, commonly observed in 90-K superconductor $YBa_2Cu_3O_P{7-{\delta}}$as an impurity phase. The powder X-ray diffraction analysis indicates that $Y_2BaCuO_5$ has an orthorhombic symmetry with lattice parameter of a = 12.2 $\AA$, b = 5.61 $\AA$, and c = 7.14 $\AA.$ The average g-value 2.13 observed in ESR spectrum is attributable to Cu2+ stabilized in $C_{4v}$ field. From the magnetic susceptibility ($\mu$eff = 2.29 BM) and the ESR measurements, it is confirmed that Cu(II) $3d^9$ electrons in $Y_2BaCuO_5$ are localized and can be characterized by Curie-Weiss behavior. Optical reflectance spectrum shows a broad absorption peak around 680 nm due to dxy ${\rightarrow}$ $dx^2-y^2$ eletronic transition.

• 전기학회논문지
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• 제60권2호
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• pp.349-351
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• 2011

The formation of oxide superconducting phase fabrication of superconducting wire materials and fabrication of precise superconducting material were studied for developing superconductor application technique. The $ZrO_2$ addition reduced the particle size $BaZrO_3$ trapped in the matrix after the sintering growth. The added $ZrO_2$ was converted to fine particles of $BaZrO_3$ which is the conventional sintering temperature for YBaCuO, $Y_2Ba_1Cu_1O_5$ and CuO are formed as by products of the reaction between $ZrO_2$ and YBaCuO phase. The formation of highly $BaZrO_3$ particle appears to be responsible for the refinement of $BaZrO_3$ phase after the citric acid sintering process.

• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.90-93
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• 2018

This aim of this study was to develop a process for creating bulk single-crystal YBaCuO superconductors in a high magnetic field. To support the bulk unidirectional growth of $YBa_2Cu_3O_{7-y}$, $SmBa_2Cu_3O_{7-y}$ seeds were planted inside YBaCuO composites and samples were produced by melting, enabling the growth of two YBaCuO superconductors. Due to the magnetism generated inside the superconductor of the upper sample, the magnetization inside the superconducting single crystals was evenly distributed, the sharpness of the induced magnetic force was improved, and the superconducting magnetization were significantly improved. This approach is widely applicable for the production of superconducting wires and current leads used for DC power breakers.

• Progress in Superconductivity
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• 제1권2호
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• pp.89-94
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• 2000

A YBCO superconductor was prepared in a short time by a melt infiltration process that utilizes meting of $Ba_3Cu5O_8$ powder and the infiltration into a porous $Y_2BaCuO_5$ compact. The processing parameters such as a reaction temperature and time, and atmosphere (air and $O_2$) were controlled to establish the fabrication condition. The formation of a $YBa_2Cu_3O_x$, phase and the developed microstructure are reported.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2004년도 High Temperature Superconductivity Vol.XIV
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• pp.45-45
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• 2004