• Title/Summary/Keyword: $Y_1$$Ba_2$$Cu_3$$O_{7-x}$

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Preparation of Submicron YBaCuO Powder by Sol-gel Method

  • Fan, Zhanguo;Soh, Dea-Wha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.557-560
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    • 2003
  • The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to $1.0\;{\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)O_2$ and CuO. When pH values were adjusted to $6.4{\sim}6.7,\;Ba(NO_3)O_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. After the heat treatment the transition temperature($T_c$) and critical current density($J_c$) of the $YBa_2Cu_3O_x$ samples made of the submicron powder were measured.

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The influence of Ag-additions on the superconducting properties of Hg$Ba_{2}$Cu$O_{4+7}$ materials (고온 초전도 Hg$Ba_{2}$Cu$O_{4+7}$물질에 Ag의 첨가에 따른 초전도특성 연구)

  • 송규정;하홍수;하동우;오상수;권영길;류강식
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.21-24
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    • 2001
  • A series of superconducting Hg$Ba_{2}$Cu$O_{4+7}$ materials, containing $Ag_{x}$ additions with molar fraction x = 0, 0.05, 0.1, 0.3, and 0.5, have been studied. This study has showed that Ag additions lead to changes in superconducting properties of Hg-1201 materials. In addition, according to the amount of $Ag_{x}$ additions with molar fraction x up to 0.5, both $T_{c}$ and $J_{c}$ of Hg-1201 materials generally decrease with Ag-content. These and other results are discussed in this paper.

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Local structural study of commercial grade MBa2Cu3O7-x (M = Y and/or Gd) coated conductors by polarized Raman spectroscopy

  • Moon, Hankyoul;Shin, Hae-Young;Jin, Hye-Jin;Jo, William;Yoon, Seokhyun
    • Progress in Superconductivity and Cryogenics
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    • v.17 no.4
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    • pp.25-29
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    • 2015
  • In 1987, M. K. Wu and Paul Chu discovered $Y_{1.2}Ba_{0.8}CuO_4$ (YBCO) with critical temperature ($T_c$) of 93 K. It has significantly lowered the cost of cooling of a material up to the point where superconductivity set in. Utilizing the cost reduction of attaining superconductivity and the vast amount of research to understand characteristics of high temperature oxide superconducting materials, there has been effort to use a high temperature superconductor as a coated conductor. It is important to characterize the materials precisely for stable performance before commercializing. We used polarized Raman scattering spectroscopy to study structural and stoichiometric information regarding $YBa_2Cu_3O_{7-x}$, $GdYBa_2Cu_3O_{7-x}$, and $GdBa_2Cu_3O_{7-x}$ produced by three leading groups of producing commercial grade high temperature superconductor coated conductors American Superconductor Corporation, Superpower, and SuNAM.

Hall Effect of High $T_{c}$ superconductor $Y_{1}Ba_{2}Cu_{3}O_{7-\delta}$ Thin Film (고온초전도체 $Y_{1}Ba_{2}Cu_{3}O_{7-\delta}$ 박막의 Hall 효과)

  • 허재호;류제천;김형국;김장환
    • Journal of the Korean Magnetics Society
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    • v.4 no.1
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    • pp.44-47
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    • 1994
  • High $T_{c}$ superconducting $Y_{1}Ba_{2}Cu_{3}O_{7-\delta}$ thin film was grown up for c-axis orientation by epitaxial growth method on $LaAlO_{3}$ single crystal substrate. The crystal structures of this thin film were found to be c-axis orientation by X-ray diffraction patterns. Hall effect and resistivity measurements were made by van der Pauw method. Hall resistivity was calculated from the magnetoresistivity by considering thermomagnetic effect. The relation was $pH=p_{s}tan{\alpha}_{n}-QBT\frac{S_s}{K_s}$ The measured Hall resistivity and the calculated one are in good agreement each other.

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Substitutional Effects of Na in the YB$a_2Cu_3O_{7-y}$ Oxide Superconductors

  • Hur Nam Hwi;Ha, Dong Han;Park Yong Ki;Park, Jong Chul
    • Bulletin of the Korean Chemical Society
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    • v.13 no.4
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    • pp.425-428
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    • 1992
  • Sodium substituted samples of $Y_{1-x}Na_xBa_2Cu_3O_{7-y}$ for $0.00{\leq}x{\leq}0.16$ were prepared and characterized by X-ray powder pattern, electrical resistivity and magnetic susceptibility measurements, Raman spectroscopy, and idometric titration. The Na substituted compounds have narrow solid solution limits where $0.00{\leq}x{\leq}0.16.$ As the Na concentration increases, the parent orthorhombic structure tends to gradually change to tetragonal. Small changes in the superconducting transition temperature, Tc, are observed in this solid solution region. Raman spectra for the Na phases are virtually identical with that of $YBa_2Cu_3O_7$ except that the Cu(1)-O(4) stretching mode at 504 $cm^{-1}$ and the Cu(2)-O(2,3) bending mode at 340 $cm^{-1}$ for x = 0.16 are slightly shifted. The hole concentrations of the sodium substituted compounds ranged from 0.31 to 0.33 per Cu site are increased with Na content. The substitution of $Na^+$ for $Y^{3+}$ site appears to create oxygen vacancies in the Cu-O chains, causes structural change from orthorhombic to tetragonal, and increases hole concentration in the substituted system.

Electronic Structure and Properties of High-Tc Superconductor Y-Ba-Cu-O. 1. Oxygen-deficiency in the $YBa_2Cu_3O_x $Superconductor ($6{\leq}{\times}{\leq}7$)

  • U-Hyon Paek;U-Sung Choi;Kee-Hag Lee;Chang-Hong Kim
    • Bulletin of the Korean Chemical Society
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    • v.10 no.6
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    • pp.504-509
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    • 1989
  • The effect of oxygen-deficiency on the charge distributions and orbital energies for small copper oxide clusters representing the superconducting materials $YBa_2Cu_3O_x (6{\leq}x{\leq}7)$ were investigated by the extended Huckel molecular orbital (EHMO) method with the tight-binding model. Our calculations show +3 oxidation state of Cu(1) in the $CuO_3$ chain and +2 or +1 of Cu(2) in the $CuO_2$ layers for $YBa_2Cu_3O_7$ with the nominal charge of $Cu_3$ = +7 (or +5), while for $YBa_2Cu_3O_6$ +1 oxidation state of Cu(1) and +3 (or +2) of Cu(2) in the $CuO_2$ layers with the nominal charge of $Cu_3$ = +7 (or +5). For $Cu_3O_{12}$ cluster representing $YBa_2Cu_3O_7$ with the nominal charge of $Cu_3$ = +7 the Cu(2) $d_{{x^2}-{y^2}}$ orbitals in the $CuO_2$ layers is a typical Jahn-Teller $d^9$ system with the partial hole and the Cu(1) $d_{{_z2}-{_y2}}$ orbital in the $CuO_3$ chain contains hole occupancy. For $Cu_3O_{10}$ cluster representing $YBa_2Cu_3O_6$ with the nominal charge of Cu = +5 the orbital character of the highest partially occupied MO (HPOMO) and the lowest completely unoccupied MO (LCUMO) of $Cu_3O_{12}$ representing $YBa_2Cu_3O_7$ with the nominal charge of $Cu_3$ = +7 is reversed, and the character of Cu(1) $d{{x^2}-{y^2}}$ orbital of LCUMO of the $Cu_3O_{12} $cluster is vanished. It is suggested that the local crystal field environment of Cu(1) by the oxygens in the Cu(1) chain may play a vital role in conductivity and superconductivity, either alone or through cooperative electronic coupling with the Cu(2) layers in $YBa_2Cu_3O_7.$.

Characteristic Simulation of the High Temperature Superconducting Micostrip Bandpass Filters using $Y_1Ba_2Cu_3O_{7-x}$ Films ($Y_1Ba_2Cu_3O_{7-x}$ 박막을 이용한 Ku-밴드 HTS 마이크로스트립 대역통과 필터의 전산모사 특성)

  • Park, Kyung-Kuk;Chung, Dong-Chul;Lim, Sung-Hun;Yim, Seong-Woo;Jeong, Yong-Chae;Han, Byoung-Sung
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1332-1-1332-4
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    • 1998
  • This paper described design and simulation of the high-Tc superconducting (HTS) microstrip bandpass filter (BPF) on MgO substrate using $Y_1Ba_2Cu_3O_{7-x}$ films that show superconductivity ${at \fallingdotseq}90$ K. Design parameters for the characteristic of the bandpass filter in Ku-band were obtained by approximate design formulas. It used parallel coupled stripline stepped impedance resonators (SIR). Microwave design system, MDS(EEsorf S/W) was used to derive the optimal pattern of the filters and to simulate frequency response. In computer-aided results, optimally designed HTS filters got good performance compared with the gold counter-parts on frequency response $S_{21}$, $S_{11}$.

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High Tc Superconductor, YBa2 Cu3 O7-$\delta$; (I) Its Preparation and Physicochemical Characterization (고온 초전도체 YBa2 Cu3 O7-$\delta$;(1) 합성 및 물리화학적 특성 연구)

  • 최진호;변송호;홍승태;정덕영;최석용;김배환;김진태;노동윤;유한일
    • Journal of the Korean Ceramic Society
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    • v.25 no.2
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    • pp.154-160
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    • 1988
  • Almost single phase of Y1Ba2Cu3Ox, which exhibits the onset of superconducting transition at 90K, has been prepared via a conventional ceramic processing route followed by an anneal for a period of 10 hours at 45$0^{\circ}C$ in an atmosphere of 100% O2. The mean value for the oxygen content has been determined as x=6.85$\pm$0.02 by an iodometric titration technique. X-ray photoemission spectra are found to be consistent with a mixture of the d8(Cu3+) and d9(Cu2+) as the ground state and reveals that the local concentration of Cu3+ decreases with depth from the surface where x corresponds to 7.0. This is explained as being associated with the intercalation of oxygen during cooling from the annealing temperature.

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Optical investigation of high critical-current $Gd_{1+x}Ba_{2-x}Cu_3O_7$ coated conductors

  • Kim, G.;Jo, W.;Park, D.Y.;Cheong, H.;Shin, G.M.;Yoo, S.I.
    • Progress in Superconductivity and Cryogenics
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    • v.10 no.2
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    • pp.24-26
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    • 2008
  • [ $Gd_{1+x}Ba_{2-x}Cu_3O_7$ ] (GdBCO) coated conductors on IBAD-MgO templates have grown by pulsed laser deposition. Critical current of the films were measured as about 90 A/cm by a four-probe method. The optical response of the films was investigated by Raman scattering spectroscopy. According to the Raman scattering spectra, the peaks at $328\;cm^{-1}$, $451\;cm^{-1}$, $504\;cm^{-1}$ were found and assigned to one $B_{1g}$ mode and two $A_{1g}$ modes, respectively. The high critical-current carrying behaviors of the GdBCO coated conductors are ascribed to their 123-structure without exchange of cation and incorporation of oxygen into the cuprates.