• Title/Summary/Keyword: $YBa_2Cu_3O_x film

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Fabrication of YSZ buffer layer for YBCO coated conductor by MOCVD method (MOCVD법에 의한 YBCO coated conductor용 YSZ 완충층 제작)

  • 선종원;김형섭;정충환;전병혁;김찬중
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.02a
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    • pp.129-132
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    • 2003
  • Yttria stabilized zirconia (YSZ) buffer layers were deposited by a metal organic chemical vapor deposition (MOCVD) technique using single liquid source for the application of YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) coated conductor. Y:Zr mole ratio was 0.2:0.8, and tetrahydrofuran (THF) was used as a solvent. The (100) single crystal MgO substrate was used for searching deposition condition. Bi-axially oriented CeO$_2$ and NiO films were fabricated on {100}〈001〉 Ni substrate by the same method and used as templates. At a constant working pressure of 10 Torr, the deposition temperatures (660~80$0^{\circ}C$) and oxygen flow rates (100~500 sccm) were changed to find the optimum deposition condition. The best (100) oriented YSZ film on MgO was obtained at 74$0^{\circ}C$ and $O_2$ flow rate of 300 sccm. For YSZ buffer layer with this deposition condition on CeO$_2$/Ni template, full width half maximum (FWHM) values of the in-plane and out-of-plane alignments were 10.6$^{\circ}$ and 9.8$^{\circ}$, respectively. The SEM image of YSZ film on CeO$_2$/Ni showed surface morphologies without microcrack.k.

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Prepatation of$(Ba_{0.5}, Sr_{0.5}) Tio_3$thin folms by Laser Ablation technique and their electrical properties with different electrodes (Laser Ablation에 의한 $(Ba_{0.5}, Sr_{0.5}) Tio_3$박막의 제조와 전극에 따른 전기적 특성)

  • Yun, Sun-Gil;Safari, A.
    • Korean Journal of Materials Research
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    • v.4 no.4
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    • pp.401-405
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    • 1994
  • The chemical composition and electrical properties were investigated for epitaxially crystallized $(Ba_{0.5}Sr_{0.5})Tio_3$ (BST) films deposited on Pt and $YBa_Cu_3O_{7-x}$(YBCO) electrodes by laser ablation technique. The crystalline quality of the heteroepitaxial BST films deposited on Pt bottom electrode was found to be better than that of BST film on YBCO electrode by the RBS analysis. Films deposited at $600^{\circ}C$ on Pt electrode showed a dielectric constant of 320 and a dissipation factor of 0.023 at 100kHz. Leakage current density of BST films on Pt electrode was smaller than that on YBCO bottom electrode. Their leakage current density was about 0.8$\mu \; A/ \textrm{cm}^2$ at an applied electric field of 0.15MV/cm.

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Electrophoretic Deposition of YBCO powder in mixed suspension solution of iso-prophanol and iso-buthanol (이소프로판올과 이소부탄을 용매에서의 YBCO 분말 영동전착)

  • ;;;Korobova N.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.288-291
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    • 2001
  • It is very important to select suspension solution for forming electrophoretic deposited YBCO thick film, because it is heavily affected to its superconducting properties. In this paper, high-temperature superconductor films of YBa$_2$Cu$_3$$O_{7-x}$ were fabricated by electrophoretic deposition (EPD) from alcohol-based suspension such as iso-propanol, iso-butanol, and their mixture. For the formation of YBCO dense and adherent coating on a silver wire by EPD, 1% PEG(1000) 2 $m\ell$, as a additive for making their surface crack-free, was used for electrophoresis. As a results, the cracks were considerably decreased and the superconducting critical current density (J$_{c}$) without/with PEG was 1200 A/$\textrm{cm}^2$ and 2020 A/$\textrm{cm}^2$, which films deposited in mix ism-propanol and iso-butanol suspension.ion.

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Features and Properties of $YBa_2$$Cu_3$$O_{7-x}$ Films Grown on SrTi$O_3$ by High Frequency PLD

  • Shi, D.Q.;Ko, R.K.;Song, K.J.;Chung, J.K.;Choi, S.J.;Park, Y.M.;Shin, K.C.;Yoo, S.I.;Park, C.
    • Progress in Superconductivity
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    • v.5 no.1
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    • pp.75-79
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    • 2003
  • YBCO films were deposited with various thicknesses from 100nm to 1.6$\mu\textrm{m}$ on single crystal $SrTiO_3$ substrates by pulsed laser deposition (PLD). The effects of different deposition conditions, especially different deposition rates by means of changing the pulsed laser frequency up to 200Hz, on the J$_{c}$ value were studied. For YBCO film with the thickness of 200nm, the $J_{c}$ value of $2.1MA/\textrm{cm}^2$ has been achieved under the high deposition rate of 3.2nm/s (190nm/min). The $J_{c}$ can be maintained greater than $1M/\textrm{cm}^2$ with the thickness less than 1$\mu\textrm{m}$. The X-ray analysis was used to examine the texture, crystallization and surface quality. The SEM was employed to analyze the surface of YBCO, and it was shown the surface of YBCO film became rougher with increasing the thickness. There were many large singular outgrowths and networks of outgrowths on the surface of YBCO films which lowered the density of thick YBCO film. The outgrowth network was probably the a-axis YBCO corresponding to XRD $\theta$-2$\theta$scan and $\chi$-scan which were used to characterize a-axis orientation of YBCO film. The reason for J$_{c}$ declining with increasing the thickness was studied and discussed.sed.

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Study on Broadband HTS Antenna Array for Satellite Communication (위성통신용 광대역 고온초전도 배열 안테나에 관한 연구)

  • 정동철;윤창훈
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.7
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    • pp.770-775
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    • 2004
  • Although $High-T_c $superconducting HTS antennas have high efficiency and high gain, narrow bandwidth due to the high Q is the major limitation for application of satellite communication and mobile communication. Defining bandwidth as the frequency range over which standing wave ratio (SWR) is 2:1 or less, HTS antenna bandwidths are typically less than 1 %. Thus considerable effort has been focused on developing HTS antennas for broadband operation. In this work the HTS antenna array, using the bipin antenna which consisted of two triangle-radiation patches, was designed and fabricated using a ${YBa}_2{Cu}_3{O}_7x (YBCO)$ superconducting thin film on a MgO substrate for broadband operation. Also gold antennas with the same dimension as our HTS antennas were fabricated on the MgO substrate for the comparison. Experimental results for both antennas were reported in terms of radiation patterns, return losses, bandwidths and other various characteristics. The center frequency of HTS antennas was 20.28 GHz and the bandwidth obtained was significant 10 %.

Fabrication and Characterization of Wideband HTS Antennas for Satellite to Satellite Communication (위성 대 위성 통신용 광대역 HTS 안테나 제작 및 특성 해석)

  • 정동철
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.12
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    • pp.573-577
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    • 2002
  • We designed wideband HTS antennas which consists of two triangle -radiation patches using a $YBa_2Cu_3O_{7-X}$ (YBCO) superconducting thin film. The major limitation of high-Tc superconducting (HTS) microstrip antennas is the narrow bandwidth due to the high Q and thin substrate. Defining bandwidth as the frequency range over which standing wave ratio (SWR) 2:1 or less, HTS antenna bandwidths are typically 0.85 % to 1.1 %. Thus considerable effort has been focused on developing antennas for broadband operation. To calculate input impedance and design of the broadband HTS antennas a moment method technique was used. The HTS antenna fabricated in this work was designed for K-band, which is useful band for satellite to satellite communications. The bandwidth obtained was a significant 6.7 % and the other measured performance of our HTS antenna, including the bandwidth, radiation Pattern, efficiency, standing wave ratio (SWR) and return losses was reported.

Fabrication and Characterization of Wideband HTS Antennas for Satellite to Satellite Communication (위성 대 위성 통신용 광대역 HTS 안테나 제작 및 특성 해석)

  • 정동철;최명호;황종선;강형곤;한병성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.523-526
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    • 2002
  • We designed wideband HTS antennas which consists of two triangle-radiation patches using a YBa$_2$Cu$_3$O$\sub$7-x/ (YBCO) superconducting thin film. The major limitation of high-Tc superconducting (HTS) microstrip antennas is the narrow bandwidth due to the high Q and thin substrate. Defining bandwidth as the frequency range over which standing wave ratio (SWR) 2:1 or less, HTS antenna bandwidths are typically 0.85% to 1.1%. Thus considerable effort has been focused on developing antennas for broadband operation. To calculate input impedance and design of the broadband HTS antennas a moment method technique was used. The HTS antenna fabricated in this work was designed for K-band, which is useful band for satellite-to-satellite communications. The bandwidth obtained was a significant 6.7% and the other measured performance of our HTS antenna, including the bandwidth, radiation Pattern, efficiency, standing wave ratio (SWR) and return losses was reported.

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Fabrication of YBCO coated conductors by PLD continuous reel-to-reel processing (PLD 연속 공정을 통한 YBCO coated conductor 제조)

  • ;;Donggqi Shi
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.10a
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    • pp.150-152
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    • 2003
  • YBa$_2$Cu$_3$O$_{7-{\delta}}$(YBCO) coated conductors were deposited by pulsed laser deposition (PLD) on short buffered substrate in continuous PLD reel-to-reel system. The oxide multilayer buffered substrate of architectures of CeO$_2$/YSZ/Y$_2$O$_3$was fabricated by PLD at steady status. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM) The FWHM of the X-ray $\omega$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current at 77K self-field of 19A, critical temperature of 86K, and current density of 2MA/$\textrm{cm}^2$ were measured. The film also exhibits a homogeneous and dense surface morphology.e morphology.

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The effect of annealing temperature and solvent on the fabrication of YBCO thin films by MOD-TFA process (MOD-TFA 공정으로 YBCO 박막제조 시 열처리 온도와 용매의 영향)

  • 허순영;유재무;김영국;고재웅;이동철
    • Progress in Superconductivity
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    • v.5 no.1
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    • pp.84-87
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    • 2003
  • $YBa_2$$Cu_3$$O_{7-x}$ (YBCO) thin films were fabricated by MOD-TFA process via dip-coating method on LaAlO$_3$, (LAO) single crystalline substrates. In this study, we investigated effect of annealing temperature and solvent on the microstructure and texture of YBCO thin films. The precursor films were annealed at various temperature to improve surface morphologies and phase purities. It was shown that the films annealed at relatively lower and higher temperature exhibit low phase purity and crystallinity. The effect of various solvents on surface morphologies and second phase has been investigated.

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