• Title/Summary/Keyword: YBA

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Epitaxial Growth of Pulsed-Laser Deposited Bi4Ti3O12/LaAlO3 Thin Films and Bi4Ti3O12/YBa2Cu3O7-x/LaAlO3 Heterostructure (펄스레이저 증착법으로 제작된 $Bi_4Ti_3O_{12}/LaAlO_3$ 박막과 $Bi_4Ti_3O_{12}/YBa_2Cu_3O_{7-x}/LaAlO_3$ 복합구조의 에피 성장)

  • Jo, Wol-Ryeom;Jo, Hak-Ju;No, Tae-Won
    • Korean Journal of Crystallography
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    • v.5 no.2
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    • pp.85-92
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    • 1994

  • Ferroelectric Bi4Ti3012 thin films have been grown on LaAlO(001) by Pulsed-laser deposition. Phase formation and structural films prepared of the films prepared at varigus deposition temperatures are investigated using x-ray diffraction The film grown at 740℃ shows epitaxial growth behavior with c-akis normal to the substrate. N2tBmstiucCures of Bi4Ti3012/YBa2Cu307-x/LaAIO3(001) have been in-situ grown. Even though the a-and b-axes of the Yba2Cu307-x layer show epitaxial growth behavior.

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Characterization of $YBa_2Cu_3O_{7-x}F_y$ Superconducting Materials Made by a Sol-Gel Process (졸-겔법으로 제조한 $YBa_2Cu_3O_{7-x}F_y$ 초전도물질의 특성분석)

  • 김봉흡;강형부;김현택
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.41 no.5
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    • pp.525-532
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    • 1992

  • Fluorine-doped YBaS12TCuS13TOS17-xTFS1yT superconducting materials with y varing two orders of magnitude form 0.02 to 2.0 have been prepared by a sol-gel process by using metal nitrate salts, sodium hydroxide and sodium fluoride. Fluorine contents have been measured using an ion-selective electrode. All fluorine doped as reactant were found to be present in the resulted samples. From the observation of XRD it has been concluded that the samples with y 0.2 formed simply the single phase of perovskite structure, whereas those with y 0.5 yielded together some compounds such as BaFS12T, YFS13T and CuO in the resulted samples. The observation of solid state S019TF NMR has been carried out in order to check whether fluorine was actually incorporated into the lattice sites, and the experimental results revealed that the mole ratio of fluorine incorporated into the lattice sites of YBaS12TCuS13TOS17-xT was approximately 0.2 per mole of the compound. Also electrical resistivity measurement indicated that onset transition temperature has the tendency to increase slightly with increasing y in the dilute region as y 0.2.

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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 $YBa_2Cu_3O_7.$.

  • https://doi.org/10.5012/bkcs.1989.10.6.504 인용 PDF