• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2006년도 추계학술발표회 초록집
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• pp.25-26
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• 2006

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2005년도 High Temperature Superconductivity Vol.XV
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• pp.79-79
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• 2005

• 전기의세계
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• 제56권6호
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• pp.32-38
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• 2007

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.524-527
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• 2007

이온 빔 스퍼터법을 이용하여 저속성장으로 동시 증착에 의해 $Bi_2Sr_2Ca_{n-1}Cu_nO_x$(n=0, 1, 2) 박막을 제작하였다. Bi 2212 상은 기판온도 $750\sim795^{\circ}C$의 범위에서 나타났으며, $750^{\circ}C$보다 저온 측에서는 Bi 2201의 단일강이 존재하였나. 그러나, 조성과 관계되는 $PO_3$에 대해서 크게 변하지 않았다. 그리고 임계온도(Tc)가 $45\sim90K$ 가지는 c축 배향한 고품질의 Bi 2212 박막을 얻었다. 소수의 박막에서는 소량의 CuO가 불순물로 관찰되었으며, 얻어진 모든 박막에서 $CaCuO_2$의 불순물 상은 관찰되지 않았다.

• 한국세라믹학회지
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• 제40권6호
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• pp.530-538
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• 2003

110 K 상의 산화물 고온초전도체를 B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+}$$\delta$의 출발조성비로 고상반응법에 의해 합성하였다. 합성된 Bi계 110 K 상의 산화물 고온초전도 물질을 다시 분말 상태로 만든 후, MgO 금속산화물 분말을 5~50 wt%의 각 비율로 혼합하였다. MgO 금속산화물 분말이 혼합된 시편들을 820~86$0^{\circ}C$로 24시간동안 최종 소결시켰다. 그 후, 각 시편들에 대하여 x-선, $T_{c}$, SEM 등을 측정하여 MgO 금속산화물 혼합량에 대한 초전도특성 및 표면의 입자 크기 변화 등에 대한 조사를 진행하였다. MgO 금속산화물의 혼합량이 증가됨에 따라 MgO 관련 피크들의 강도 및 2212 상들의 피크들의 비율은 증가되었고, 시편 내 2223 상의 비율은 감소하고 2212상의 비율은 증가되었다.다.은 증가되었다.다.

• Progress in Superconductivity
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• 제5권2호
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• pp.124-127
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• 2004

Many of research efforts have been focused on the improvement of critical current density (Jc) of silver-sheathed Bi-2223 tapes far practical applications. In this study, the transformation of Bi-2212 phase was investigated, which was transformed to orthorhombic from tetragonal through pre-annealing during powder packing and drawing process. The relationship between hardness of Bi-2212 orthorhombic phase and workability of Bi-2223/Ag tape was investigated. Bi-2223 superconducting wires with 55 filaments were fabricated by stacking and drawing process with different heat-treatment histories. Before rolling process, round wires were pre-annealing at 76$0^{\circ}C$ and in a low oxygen partial pressure. We confirmed that pre-annealing step was to transform to Bi-2212 orthorhombic structure from Bi-2212 tetragonal structure and to reduce the formation of second phases. However the breakages were created at Ag-alloy clad during rolling for pre-annealed Bi-22231Ag tapes. Several pre-annealing scenarios were introduced to reduce the breakages during rolling process. Microstructure and critical current density of pre-annealed Bi-2223 superconducting tapes were investigated. We could achieve proper pre-annealing conditions for Ag-alloy clad Bi-2223 superconducting tapes.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.349-358
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• 2000

Fabrication and Characterization of Bi$_{2}$/Sr$_{2}$/CaCu$_{2}$/O$_{8}$(Bi2212) superconductor thick films were fabricated successfully on C tapes by liquid reaction between Cu-free precursors of Bi$_{x}$/SrCaO/$_{y}$(x=1.2-2) and Cu tapes. Cu-free Bi-Sr-Ca-O powder mixtures were screen-printed on Cu tapes and heat-treated at 850-87$0^{\circ}C$ for several minutes in air oxygen nitrogen and low oxygen pressure. In order to obtain the optimum heat-treatment condition we studied the effect of the precursor composition the printing thickness and the heat-treatment atmosphere on the superconducting properties of Bi2212 films and the reaction mechanism. Microstructures and phases of thick films were analyzed by films and the reaction mechanism. Microstructures and phases of thick films were analyzed by optical microscope and XRD. The electric properties of superonducting films were examined by the four probe method. At heat-treatment temperature the thick films were in a partially molten state by liquid reaction between CuO of the oxidized copper tape and the precursors which were printed on Cu tapes. During the heat-treatment procedure Bi2212 superconducting particle nucleate and grow in preferred orientations.ons.s.

• 한국정보통신학회논문지
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• 제11권6호
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• pp.1115-1121
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• 2007

이온 빔 스퍼터법을 이용하여 저속성장으로 동시 증착에 의해 $Bi_2Sr_2Ca{_{n-1}}Cu_nO_x$(n=0,1,2) 박막을 제작하였다. Bi 2212 상은 기판온도 $750{\sim}795^{\circ}C$의 범위에서 나타났으며, $750^{\circ}C$보다 저온 측에서는 Bi 2201의 단일상이 존재하였다. 그러나, 조성과 관계되는 $PO_3$은 압력 변화에 대해서는 관찰되지 않았다. 그리고 $45{\sim}90K$의 임계온도(Tc)를 갖는 c축 배향한 고품질의 Bi 2212 박막을 얻었다. 소수의 박막에서는 소량의 CuO가 불순물로 관찰되었으며, 얻어진 모든 박막에서 $CaCuO_2$ 의 불순물 상은 관찰되지 않았다.

• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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• pp.425-433
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• 1997

BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 82$0^{\circ}C$ and the highly condensed ozone gas pressure(PO$_3$) in vacuum chamber was varied between 2.0$\times$10$^{-6}$ and 2.3$\times$10$^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795$^{\circ}C$ and single phase of Bi 2201 existed in the lower region than 785$^{\circ}C$. Whereas, PO$_3$dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with T$_{c}$(onset) of about 90 K and T$_{c}$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as CaCuO$_2$was observed in all of the obtained films.lms.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.27-30
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• 2003

The Bi2212 based HTS tubes with 4 different compositions, Bi:Sr:Ca:Cu = 2.0:2.0:1.0:2.0, 2.1:2.0:1.0:2.0,2.2:1.8:1.0:2.0 and 2.2:1.8.1.0.2:2 with 10% of SrSO$_4$ were studied. For tube fabrication the optimum range of melt temperatures and preheating temperature and time for mold were 105$0^{\circ}C$~110$0^{\circ}C$ and 55$0^{\circ}C$ for 30min respectively. The mold rotating speed was 1000rpm. Typical tube dimension was 30/24mm in outside/inside diameter and 60mm in length. A tube was annealed at 84$0^{\circ}C$ for 40 hours in oxygen atmosphere. The plate like grains more than 20${\mu}{\textrm}{m}$ were well developed along the rotating direction of mold regardless of initial chemical compositions. The specimen with Bi2212 composition exhibited $T_c$ of 83K while the specimen with other compositions are lower than 60K. The measured $I_c and J_c$ at 77K(B = 0T) in Bi2212 composition were about 80A and 266A/$\textrm{cm}^2$.