• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제55권9호
• /
• pp.442-445
• /
• 2006

In order to realize the commercial application of HTSC materials, it is necessary to develop the fabrication process of high Tc oxide superconductor materials with desired shape and for practical application and high critical current density as well as good mechanical strength which can withstand high lorenz force generated at high magnetic field. Much studies have been concentrated to develop the fabrication technique for high critical current density but still there are a lot of gap which should be overcome for large scale application of HTSC materials at liquid nitrogen temperature. Recently some new fabrication techniques have been developed for YBaCuO bulk superconductor with high mechanical strength and critical current density. In this project, the establishment of fabrication condition and additive effects of second elements were examined so as to improve the related properties to the practical use of YBaCuO superconductor, and we reported the production of the YBaCuO high Tc superconductor by the pyrolysis method.

• 비파괴검사학회지
• /
• 제35권5호
• /
• pp.314-320
• /
• 2015

본 연구에서는 펨토초의 펄스폭을 갖는 극초단 레이저를 이용하여 나노 스케일 초전도 재료의 열전도율을 측정하였다. 95 nm 두께의 이트륨바륨구리산화물($YBa_2Cu_3O_7-x$)을 티탄산스트론튬($SrTiO_3$) 기판 위에 펄스레이저 증착법으로 적층하여 시편을 제작하였으며, 유한차분법으로 1차원 과도 열전도 방정식의 해를 구하여 측정결과와 비교하였다. 곡선맞춤을 통하여 1.2 W/mK의 열전도율을 얻었으며, 이는 동일 재료의 벌크(bulk) 물성치에 비하여 낮은 값으로 확인된다. 본 연구는 마이크로/나노소자의 열설계를 위한 초전도 나노재료의 특성을 규명한다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.42-43
• /
• 2008

The numerous application of ceramic superconducting bulk such as magnetic levitation train flywheel energy, levitation transpormation, magnetic bulk magnet etc. To obtain YBaCuO materials in the form of large single crystals are necessary. A refreshment and uniform distributon of the superconducting particle in the sample. The enhancement of the critical density was ascribe to a fine dispersion of the superconducting particle.

• 한국전기전자재료학회논문지
• /
• 제34권6호
• /
• pp.461-465
• /
• 2021

A diffusion heat treatment process for YBa₂Cu₃O_7-y bulk superconductor in a Gd₂O₃ powder was attempted. As a result of measuring the critical temperature of the superconducting bulk, there was no change in the superconducting transition temperature as the Gd particles diffused into the YBa₂Cu₃O_7-y lattice, resulting in dense microstructure. As a result of measuring the critical current, the critical current density (J_c) of the superconducting bulk having treated by the Gd thermal diffusion treatment at 0 T increased to 3×10⁴ A/cm² at 0 T, which was higher than that of the superconducting bulk without thermal diffusion treatment. The surface magnetic force of the superconducting bulk with Gd thermal diffusion treatment was observed at the center of the superconducting bulk with the maximum trapped magnetic force (Hmax) of 1.51 kG. This result means that the Gd thermal diffusion treatment contributes to improving the critical current density Jc of YBa₂Cu₃O_7-y, and it is believed that Gd particles migrating into the superconducting bulk through thermal diffusion either fill the surface pores of YBa₂Cu₃O_7-y superconductors or act as a flux pinning center.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제55권7호
• /
• pp.364-366
• /
• 2006

In order to realize the commercial application of HTSC materials, it is necessary to develop the fabrication process of high Tc oxide superconductor materials with desired shape and for practical application and high critical current density as well as good mechanical strength which can withstand high lorenz force generated at high magnetic field. Much studies have been concentrated to develop the fabrication technique for high critical current density but still there are a lot of gap which should be overcome for large scale application of HTSC materials at liquid nitrogen temperature. Recently some new fabrication techniques have been developed for YBaCuO bulk superconductor with high mechanical strength and critical current density. In this project, the establishment of fabrication condition and additive effects of second elements were examined so as to improve the related properties to the practical use of YBaCuO superconductor, and we reported the production of the YBaCuO high Tc superconductor by the pyrolysis method.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.349-352
• /
• 2004

The improvement of critical temperature $(T_c)$, critical magnetic field $(H_c)$, and critical current density $(J_c)$ of superconductor is important for practical applications. In this study, the additives such as metal oxides were used to improve the preparation conditions of $YBa_2Cu_3O_x$ superconducting bulk samples and depending on additives the properties of $YBa_2Cu_3O_x$ superconductor were studied. The effects of additives to the density, grain alignment, and porosity of samples that affect the critical current density of superconductor also have been investigated.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
• /
• pp.49.4-49
• /
• 1998

• 한국초전도ㆍ저온공학회논문지
• /
• 제22권1호
• /
• pp.1-6
• /
• 2020

This is a parameter study for the direct fabrication of a large grain YBCO bulk superconductors using Y₂O₃, BaCO₃ and CuO powders without any grinding step. The cracks, which have been formed due to volume contraction during calcination step, have been prevented by controlling the heating rate at 930~950 ℃. It has been observed that multi-grain growth has occurred due to the dissolution of Sm123 seed due to the retention of carbon in Ba-Cu-O melt. In order to accelerate the carbon release in prior calcination heat treatment, the reduction of pellet thickness and the drilling of artificial holes have been applied. Single-grain YBCO bulk superconductor has been successfully fabricated by stacking multiple thin slab. However, the crack formation has been rather prominent for the compact with artificial holes. The use of buffer pellet, which is supposed to act as diffusion barrier, has prevented the dissolution of Sm123 seed crystal and has led to the growth of single grain of high content of carbon containing specimen.

• Progress in Superconductivity
• /
• 제12권1호
• /
• pp.27-31
• /
• 2010

A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. Many aspects of the quasi-static behavior of flywheel rotors still need to be studied closely, and the rotors require a stable and highly efficient supporting system such as high temperature superconductor (HTS) bearings, which offer dynamic stability without the use of active control. Quasi-static properties of HTS bearings in the radial direction provide data to solve problems which may occur in a running system. Since stiffness in countering rotor vibration is the main parameter for designing an HTS bearing system, we investigated the quasi-static properties of the magnetic force between permanent magnets(PMs) and HTS bulks in the radial direction. We measured radial stiffness, and discovered that bearing stiffness varied greatly depending on the number of active HTS bulks. This is valuable data for predicting the change in stiffness during partial HTS bearing failure. The quasi-static test results are used for optimal design and performance prediction for the 100 kWh class superconductor bearing.

• 한국전기전자재료학회논문지
• /
• 제34권6호
• /
• pp.438-441
• /
• 2021

The electrical characteristics of single-crystal composite superconductors produced by a melting process were studied by neutron irradiation. In order to improve the current characteristics of the YBa₂Cu₃O_7-y superconductor, it is necessary to form an effective flux pinning center inside the superconductor. In this study, an increase in flux pinning was attempted through neutron irradiation onto YBa₂Cu₃O_7-y superconductors. The neutron irradiation was performed at 30 MeV for 500 sec, The electrical properties of the superconductors were measured in a magnetic field of 5 Tesla at 50 K using a magnetic properties measurement system (MPMS). After neutron irradiation, the critical current density of the YBa₂Cu₃O_7-y superconductor in a 1 Tesla magnetic field was 1×10⁵ A/cm². Once neutrons were irradiated at 30 MeV and 10 μA for 500 sec, the critical current density was observed to increase significantly. When neutrons are irradiated to a superconductor, micro-defects are created in the superconductor, and they act as flux pinning centers that hold the magnetic field generated when an electric current flows.