• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.249-250
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• 2006

Bi-2212/Ag ROSAT용 와이어의 제작은 PIT법으로 제작된 단일 필라멘트가 사용되었다. 제작된 필라멘트를 압연하여 너비 8.6mm, 두께 2.15mm의 압연 테입을 제조한 후 4개씩 적층하여 3 부분의 마름모로 만들어 다시 내경 17.2mm의 Ag튜브에 적층하여 ROSAT 와이어를 약 150 mm로 제작하였다. 제작된 ROSAT 와이어는 산소분위기에서 약 60시간 동안 열처리 되었다. 이때 열처리 온도와 최고점에서의 유지시간에 따른 Bi-2212/Ag ROSAT 와이어의 전기적 특성을 평가 하였다. 기존의 Bi-2212/Ag 와이어에 비해 압연, 적층, 인발하여 제작된 동일한 크기의 ROSAT 와이어가 향상된 전기적 특성을 나타내었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.615-618
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• 2003

This paper presents Bi thin films have been fabricated by atomic layer-by-layer deposition and co-deposition at an IBS method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(l00) 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 820 $^{\circ}C$ 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.91-92
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• 2006

The important merit of Bi-2212/Ag wire is to apply cable as round wire state. Bi-2212 high Tc superconducting wires were fabricated in order to apply Rutherford cable near the future. Various Ag ratio from 0.22 to 0.42 of Ag tubes for PID (powder-In-Tube) process were used to investigate the workability and to prevent breakage of filaments during drawing. In order to find proper heat treatment condition, we investigated micro-structure of Bi-2212/Ag wires by using differential thermal analysis, XRD and SEM. The effect of atmosphere on the peritectic decomposition temperature of precursor was investigated. The shape of grain was observed by SEM to investigate Bi-2212 phase formation in filaments. The higher of Ag ratio of mono filament had the higher critical current density, Jc. The wire with 0.42 of Ag ratio showed 7,886 A/cm2 of Jc at 77K.

• Progress in Superconductivity
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• v.9 no.1
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• pp.18-22
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• 2007

For interlayer tunneling spectroscopy using a small stack of $Bi_2Sr_2CaCu_2O_{8+x}$ (Bi-2212) intrinsic junctions in a high-bias range, large self-heating takes place due to the poor thermal conductivity of Bi-2212. In this study, we numerically estimate the self-heating around a Bi-2212 sample stack for I-V or dI/dV-V measurements. Our results show that the temperature discrepancy between the Bi-2212 sample stack and top Au electrodes due to bias-induced self-heating is small enough along the c-axis direction of Bi-2212. On the other hand, the lateral temperature discrepancy between the sample stack and the Bi-2212 on-chip thermometer stack can be as large as ${\sim}20\;K$ for the highest bias required to observe the pseudogap hump structure. We thus suggest a new in-situ ac thermometry, employing the Au current-bias electrode itself deposited on top of the sample stack as the resistive thermometer layer, which is supposed to allow safe temperature measurements for the interlayer tunneling spectroscopy.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.282-284
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• 2007

The superconductor characteristics of BSCCO spray films by Heat treatment was studied. $Bi_2Sr_2CaCu_2O_x$(Bi-2212) is high-Tc superconductor(HTS) coatings have been prepared by Heat treatment. Where high current carrying capabilities are required and therefore thick film and bulk material are called for, the Bi2Sr2Ca1Cu2O8-d(Bi-2212)compound has evoleved as one of the most promising. and the Bi-2212 HTS coating layer is synthesized through the peritectic reaction between Sr-Ca-Cu oxide coating layer and Bi-Cu oxide coating layer by partial melting process. The superconducting characteristics depends on the spray distance which was related to the spray particle melt. The Bi-2212 HTS layer consists of the whisker growth and secondary phase in 2212 layer were observed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.536-539
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• 2007

BSCCO am films fabricated by using the evaporation method at various substrate temperatures, Tsub and ozone gas pressures $PO_3$. Despite setting the composition of thin film Bi2223, Bi2201, Bi2212 and Bi2223 phase were appeared. It was confirmed the obtained field of stabilizing phase was represented in the diagonal direction of the right below end in the Arrhenius plot of temperature of the substrate and $PO_3$, and it was distributed in the rezone. The XRD peak of the generated film continuously changed according to the substrate temperature. This demonstrates the existence of mixed crystal composition where the phases of Bi2201, Bi2212 and Bi2223 are mixed in the crystal structure; and the single-phase film of each phase exist in a very rezone of temperature and gas pressure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.104-105
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• 2000

High quality BSCCO thin films have been fabricated by means of an ion beam sputtering at various substrate temperatures, T$_{sub}$, and ozone gas pressures, PO$_3$. The correlation diagrams of the BSCCO phases appeared against T$_{sub}$ and PO$_3$are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 phases as well as Bi2212 one come out as stable phases depending on T$_{sub}$ and PO$_3$. From these results, the thermodynamic evaluations of ΔH and ΔS which are related with Gibbs'free energy change for single Bi2212 or Bi2223 phase are performed.ormed.i2212 or Bi2223 phase are performed.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.296-299
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• 1999

Bi$_2Sr_2CaCu_2O$(Bi-2212) thick films were fabricated on Y2l1 substrate by screen printing method. And the samples were annealed in various atmospheres, respectively. Though samples had many voids, the sample annealed in N$_2$ ; O$_2$ = 1:0 atmosphere and the sample in N$_2$ : O$_2$ = 0:1 showed some Bi 2212 low phase in comparison to other samples. The thickness of Bi-2212 on Y2ll substrates was about 20 ${\mu}$m.

• Progress in Superconductivity and Cryogenics
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• v.5 no.2
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• pp.66-70
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• 2003

Transient magnetic diffusion process in a melt-cast Bi2Sr2CaCu20X(Bi-2212) tube was studied by experimental and numerical analyses. The transient diffusion partial differential equation is transformed into an ordinary differential equation by integral method. The penetration depth of magnetic field into a superconducting tube is obtained by solving the differential equation numerically. The results show that the penetration depth as a function of time which is somewhat different from the results by Bean's critical state model. The reason of the difference between the present results and that of Bean's model is discussed and compared in this paper. This experiment measure the magnetic flux density in the supercondutor after supply direct-current of Bi-2212 rounded by copper coil. This study was discussed of valid of a previous numerical solution which is compared by the penetrate time and the magnetic flux density difference of between the present results and the numerical solution.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.108-111
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• 2000

Bi2212 and Bi2223 thin films are fabricated by ion beam sputtering method. Three phases of Bi2201, Bi2212 and Bi2223 appear as stable ones in spite of the condition for thin film fabrication of Bi2212 and bi2223 compositions, depending on substrate temperature(T$\sub$sub/) and ozone pressure (PO$_3$). It is found out that these phases show similar T$\sub$sub/ and PO$_3$dependence, and that the stable regions of these phases are limited within very narrow temperature.