• Title/Summary/Keyword: Superconducting Thin Film

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Fabrication and characteristic analysis of High-Tc superconducting microstrip antennas using direct inset feeding technique (직접삽입 급전 방식을 이용한 고온초전도 마이크로스트립 안테나의 제작 및 특성 해석)

  • Chung, Dong-Chul;Han, Byoung-Sung;Kim, Jin;Ryu, Ki-Su;Hong, Suck-Yong;Lee, Jong-Ha
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.37 no.1
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    • pp.70-78
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    • 2000
  • In applying high-${\underline{T_c}}$ superconducting material to microwave devices, Uncertainty of electromagnetics of high-${\underline{T_c}}$ superconductor(HTS) and the temperature dependence of the substrate fits with HTS thin film cause difficulty in realization of such antenna for industrial applications. It must be noted to characteristic the HTS antenna in contrast with normal conducting counterpart for this real application. In this paper, a comparative study between HTS microstrip antennas and gold antennas was reported in terms of the return loss, the characteristic impedance, efficiency, and other various characteristics. HTS thin films were $YBa_2Cu_3O_{7-x}$ (YBCO) on MgO substrates. Superconducting microstrip antennas used in this work were to directly inset a microstrip transmission line into the 50 ${\Omega}$ region of the radiating patch. Measurement results of HTS antennas and gold antennas showed that usable antennas can be made using this architecture.

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A Study on the Epitaxial Growth of Superconducting Thin Film (초전도 박막의 에피택셜 성장에 관한 연구)

  • Lee, Hee-Kab;Park, Yong-Pil;Kim, Gwi-Yeol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.05c
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    • pp.208-211
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    • 2002
  • $Bi_2Sr_2CuO_x$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

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Operational characteristic of flux-lock type HTSC-FCL (자속구속형 고온초전도 전류제한기 동작 특성)

  • Lim, Sung-Hun;Choi, Hyo-Sang;Kang, Hyeong-Gon;Ko, Seok-Cheol;Lee, Jong-Hwa;Choi, Myung-Ho;Song, Jae-Joo;Han, Byoung-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05b
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    • pp.20-23
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    • 2003
  • The operational characteristics of flux-lock type high-Tc superconducting fault currentlimiters(HTSC-FCLs) was described and currents equation at each coil was derived from equivalent circuit. $YBa_{2}Cu_{3}O_{7-x}$(YBCO) thin film was used as the current limiting elements of the flux-lock type HTSC-FCL, which were fabricated by etching the YBCO thin film into 2 mm wide and 420 mm long meander line consisting of foureen stripes with different length. The 2nd peak on the current of coil 2 after a fault disappeared by current of the 3rd winding, which was installed in the flux-lock type HTSC-FCL.

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Study on fabricated RF coil using high-temperature superconductor tape and matching circuit for low field MRI system (고온초전도 선재와 정합회로를 이용한 RF coil 제작에 대한 기초연구)

  • Kim, D.H.;Ko, R.K.;Kang, B.M.;Ha, D.W.;Sohn, M.H.;Mun, C.W.
    • Progress in Superconductivity and Cryogenics
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    • v.14 no.1
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    • pp.44-47
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    • 2012
  • The substantial improvement of the signal-to-noise ratio (SNR) can be achieved with small-size samples or low-field MRI system by high-temperature superconducting(HTS) RF coil. The typical HTS RF coil made of HTS thin film is expensive and is limited the coil geometry to planar surface coil. In this study, commercial Bi-2223 HTS tapes was used as RF coil for a 0.35T permanent MRI system. It has advantages of both much lower cost and easier fabrication over HTS thin film coil. SNR gain of the image obtained from the HTS RF coil over a conventional Cu RF coil at room temperature was about 2.4-fold and 1.9-fold using the spin echo pulse sequence and gradient echo pulse sequence respectively.

Resistance distribution in large area thin film type SFCLS (박막형 대면적 초전도 한류소자에서의 저항 분포)

  • 김혜림;최효상;현옥배
    • Progress in Superconductivity and Cryogenics
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    • v.4 no.1
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    • pp.89-93
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    • 2002
  • We investigated the resistance distribution n 4"diameter SFCLS. $YBa_2CU_3O_7$ films coated in-situ with a gold layer were patterned into 3 mm wide 142 cm long meander lines by Photolithography. The limiters were tested with simulated fault currents. The resistance was uniform all over the film except at the edge. At lower source voltages, CFCLs did not quench simultaneously and the resistance distribution was less uniform. Compared with 2" diameter SFCLS 4" SFCLS had similar values and time dependence of resistivity at similar electric fields The resistance distribution was more uniform in 4" SFCLS. The area at the edge where the distribution was not uniform was around 3 mm wide in SFCLs of both sizes. The experimental results were quantitatively explained with a heat transfer concept.

Stabilized operating condition of resistive superconducting fault current limiter using YBCO film (YBCO film을 이용한 저항형 한류기의 안정적인 동작 조건)

  • 최효상;현옥배;김혜림;황시돌;김상준
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2000.02a
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    • pp.133-135
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    • 2000
  • We fabricated resistive super- conducting fault current limiters (SFCL) based on YBCO thin films grown on a 2" diameter $Al_{2}$O_{3} substrate. The minimum quench current of the current minimum quench current of the current limiting element was about 8 $A_{peak}. This SFCL successfully controlled the fault current below 14.3 $A_{peak} at the voltage of 100$V_{rms}, which is otherwise to increase up to 141$A_{peak}. and the quench completion time is less than 3 msec. The temperature of the current limiting element rose to about 200K in 3 cycles after fault. The SFCL showed reproducible characteristics during hundreds times of repeated experiments.ents.

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Quench propagation in resistive SFCL (저항형 초전도 한류기에서의 퀀치 전파)

  • 김혜림;현옥배;최효상;황시돌;김상준
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.4
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    • pp.337-342
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    • 2000
  • We fabricated resistive superconducting fault current limiters based on YB $a_{2}$/C $u_{3}$/ $O_{7}$ thin films and investigated their quench propagation characteristics. The YB $a_{2}$/C $u_{3}$/ $O_{7}$ films was coated with a gold layer and patterned into 1 mm wide meander lines by photolithography. The quench was concluded to start locally and propagates until completed. The quench propagation characteristics were explained based on the heat transfer within the film as well as between the film and the surrounding liquid nitrogen. The quench completion time depended strongly on potential fault current amplitude and not significantly on fault angle which indicates that the quench propagation speed is affected more by heat dissipation rate than by fault current increase rate. The quench completion time was 1 msec at the fault current of 65 $A_{peak/{\ak}}$.

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Establishment of Preparation Conditions for High-Tc Superconducting Y-Ba-Cu-O Thin Film by Chemical Vapor Deposition (화학증착법에 의한 고온 초전도 Y-Ba-Cu-O 박막의 제조 조건 확립에 관한 연구)

  • Park, Joung-Shik;Cho, Ik-Joon;Kim, Chun-Yeong;Lee, Hee-Gyoun;Won, Dong-Yeon;Shin, Hyung-Shik
    • Applied Chemistry for Engineering
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    • v.3 no.3
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    • pp.412-421
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    • 1992
  • The superconducting thin films have shown a growing possibility for practical application in microelectronic fields in recent years. In this study, the high Tc superconducting Y-Ba-Cu-O thin films were prepared on various substrates by chemical vapor deposition method using organic metal chelates of $Y(thd)_3$, $Ba(thd)_2$, and $Cu(thd)_2$ as source materials. The deposition reactions were carried out on single crystalline MgO(100), YSZ(100), $SrTiO_3(100)$, and polycrystalline $SrTiO_3$ substrates. Deposition thickness of thin films was linearly increased with the increase of deposition time. It turned out that the Y-Ba-Cu-O thin films on MgO(100), YSZ(100), and $SrTiO_3(100)$ single crystal substrates showed superconductivities above liquid nitrogen temperature($T_{c,onset}=87{\sim}89K$, $T_{c,zero}=85{\sim}86K$), but the one on polycrystalline $SrTiO_3$ substrate did not.

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Modeling of Electrical Transport in YBCO Single Layer Thin Films using Flux Motion Model

  • Ud Din, Fasih;Shaari, Abdul Halim;Kamalianfer, Ahmad;Navasery, Manizheh;Yar, Asfand;Talib, Zainal Abidin;Pah, Lim Kean;Kien, Chen Soo
    • Journal of Magnetics
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    • v.19 no.2
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    • pp.140-145
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    • 2014
  • The electrical transport properties of YBCO single layers thin film have been investigated using different physical techniques. For the purpose, the physical properties are probed numerically with help of simulation modelling. The physical transport properties were also estimated with temperature and magnetic fields limits using thermally-activated flux flow model with some modifications. The result of present simulation modelling indicated that the magnitude of activation energy depends on temperature and magnetic field. The simulations revealed thickness dependent physical transport properties including electrical and magnetic properties of deposited YBCO single layers thin films. Furthermore, it shows the temperature dependence of the pinning energy. In the nutshell, the result can be used to improve the Superconducting Properties ($T_c$) of the YBCO single layers thin films.

Properties Optimization for Perovskite Oxide Thin Films by Formation of Desired Microstructure

  • Liu, Xingzhao;Tao, Bowan;Wu, Chuangui;Zhang, Wanli;Li, Yanrong
    • Journal of the Korean Ceramic Society
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    • v.43 no.11 s.294
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    • pp.715-723
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    • 2006
  • Perovskite oxide materials are very important for the electronics industry, because they exhibit promising properties. With an interest in the obvious applications, significant effort has been invested in the growth of highly crystalline epitaxial perovskite oxide thin films in our laboratory. And the desired structure of films was formed to achieve excellent properties. $Y_1Ba_2Cu_3O_{7-x}$ (YBCO) superconducting thin films were simultaneously deposited on both sides of 3 inch wafer by inverted cylindrical sputtering. Values of microwave surface resistance R$_2$ (75 K, 145 GHz, 0 T) smaller than 100 m$\Omega$ were reached over the whole area of YBCO thin films by pre-seeded a self-template layer. For implementation of voltage tunable high-quality varactor, A tri-layer structured SrTiO$_3$ (STO) thin films with different tetragonal distortion degree was prepared in order to simultaneously achieve a large relative capacitance change and a small dielectric loss. Highly a-axis textured $Ba_{0.65}Sr_{0.35}TiO_3$ (BST65/35) thin films was grown on Pt/Ti/SiO$_2$/Si substrate for monolithic bolometers by introducing $Ba_{0.65}Sr_{0.35}RuO_3$ (BSR65/35) thin films as buffer layer. With the buffer layer, the leakage current density of BST65/35 thin films were greatly reduced, and the pyroelectric coefficient of $7.6\times10_{-7}$ C $cm^{-2}$ $K^{-1}$ was achieved at 6 V/$\mu$m bias and room temperature.