• Title/Summary/Keyword: Bi$_2$Sr$_2$CaCu$_2$O$_8$

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Effects of Substrate and Sintering Conditions on the Properties of Screen Printed Bi-Pb-Sr-Ca-Cu-O Superconduction Thick Films (Screen printing 방법에 의한 후막형 Bi-Pb-Sr-Ca-Cu-O 초전도체의 소결조건과 기판의 초전도성에 미치는 영향)

  • 김혜동;임호빈
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1990.10a
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    • pp.26-30
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    • 1990
  • Bi$\_$0.7/Pb$\_$0.3/Sr$_1$Ca$_1$Cu$\_$1.8/Ox thick films were screen printed on magnesia(MgO), silver and yttrium stabilized zirconia (YSZ) substrates and were sintered in a boat with cover to prevent the evaporation. The high-Tc phase increase and the low-Tc phase and Ca$_2$PbO$_4$ decrease with an increase in sintering temperature from 835$^{\circ}C$ to 860$^{\circ}C$. YSZ substrate interact strongly with the oxide resulting in poor superconductor, while the Ag and MgO substrates were satisfactory to make screen printed superconductors. The Bi$\_$0.7/Pb$\_$0.3/Sr$_1$Ca$_1$Cu$\_$1.8/Ox thick films screen printed both on Ag and MgO substrates show high Tc phase of ~85% and Tc of 96K.

Superconducting Properties of Ge Substitution for the Bi Site in the 2212 Phase of Bi-Sr-Ca-Cu-O Superconductors (Bi계 산화물 초전도체 2212상에 있어서 Bi 자리에 Ge 치환에 따른 초전도 특성)

  • 신재수;이민수;최봉수;송승용;송기영
    • Journal of the Korean Ceramic Society
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    • v.37 no.8
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    • pp.787-791
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    • 2000
  • Samples with the nominal composition, Bi2-xGexSr2CaCu2O8+$\delta$ (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by the solid-state reaction method. We have studied the effect of substitution Ge for Bi and investigated the superconducting properties by changing oxygen content with Ge substitution. It was found that temperature difference, ΔK, between TCon and TCzero was considerably smaller in the samples prepared by the intermediate pressing method than that in the samples by the solid-state reaction method. We found the solubility limit of Ge to the 80 K single phase was around x=0.3. Within the solubility limit, lattice constant c decreased with the increase of x. In the region of the 80K single phase, the onset critical temperature TCon increased and excess oxygen content decreased with increase of x.

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Superconductor characteristics of BSCCO spray films by Heat treatment (열처리에 따른 BSCCO 용사피막의 초전도특성)

  • Do, Hyeong-Jun;Park, Gyeong-Chae
    • 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.

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The magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects

  • Lee, C.W.;Shim, S.Y.;Ha, D.H.;Kim, D.H.;Lee, T.W.
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.103-106
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    • 2000
  • We have studied the magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects using micro Hall-probe array. We found that fold profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. In the magnetic relaxation measurement, the normalized relaxation rates were maximum near the center and decreased toward the edge of the sample expect zero gauss. The relaxation rates as a function of the temperature were maximum near the 40K and rapidly decreased both sides of the peak.

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Effects of annealing and impurities on the superconducting properties of$Bi_2Sr_2CaCu_2O_{8+{\delta}}$ single crystals ($Bi_2Sr_2CaCu_2O_{8+{\delta}}$ 단결정의 초전도 특성에 미치는 열처리 및 불순물의 영향)

  • N. Sato;N. Yoshimoto;M. Yoshizawa
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.2
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    • pp.137-140
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    • 1999
  • Effects of annealing and impurities on the superconducting properties were investigated by the magnetization measurement in $Bi_2Sr_2CaCu_2O_{8+{\delta}}(Bi2212)$ single crystals grown by flux method. It has been found that the superconducting properties are affected by Mg and Al impurities remarkably. The transition temperature$(T_c)$ has been lowered by the impurity of Mg. However, the diamagnetism is remarkably increased in an annealed crystal grown in MgO crucible compared to that in $Al_2O_3$ crucible. The content of Mg impurity can not be considered as a principal parameter for the decay of superconducting properties probably because the diamagnetism is remarkably improved in annealed crystal containing Mg.

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Numerical Simulation on Self-heating for Interlayer Tunneling Spectroscopy in $Bi_2Sr_2CaCu_2O_{8+x}$

  • Park, Jae-Hyun;Lee, Hu-Jong
    • 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.

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Deping characteristics of the Bi-Sr-Ca-Cu-O ceramics (Bi-Sr-Ca-Cu-O 세라믹의 도우핑 특성)

  • 박용필;김영천;황석영
    • Electrical & Electronic Materials
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    • v.9 no.1
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    • pp.1-8
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    • 1996
  • We investigated the effects of doping elements on the Bi-Sr-Ca-Cu-O ceramics. The doping elements can be classified into four groups depending on their supeconducting characteristics in the Bi-Sr-Ca-Cu-O structure. The first group of doping elements(Co, Fe, Ni and Zn) substitute into the copper site and can reduce the critical temperatures of the 2223 and 2212 phases. The second group of doping elements(Y and La) substitute into the Ca site and cause the disappearance of the 2223 phase and increase the critical temperatures in the 2212 phase. The third group of doping elements(P and K) have a tendency to decompose the superconducting phase and reduce the optimal sintering temperature. The fourth group of doping elements(B, Si, Sn and Ba) almost unaffected the superconductivity of the 2223 and 2212 phase.

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Raman-tensor analysis of phonon modes in (Pb, Bi)2Sr2CaCu2O8+δ

  • Ji Yoon Hwang;Sae Gyeol Jung;Dong Joon Song;Changyoung Kim;Seung Ryong Park
    • Progress in Superconductivity and Cryogenics
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    • v.26 no.1
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    • pp.10-13
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    • 2024
  • We performed angle-resolved Raman spectroscopy experiments on lead-doped and undoped Bi2Sr2CaCu2O8+δ(Bi2212) samples using a 660 nm laser and analyzed the Raman tensor of the phonon modes. The phonon mode was clearly observed at the 60, 103, and 630 cm-1 Raman shifts. The 60, 630 cm-1 peaks were only clearly observed when the incident and scattered light polarizations were configured to be parallel. The polarization angle dependence of the amplitude of the 60, 630 cm-1 peak on the parallel configuration shows a twofold symmetry; therefore, both peaks originate from Ag phonons and the crystal structure of Bi2212 should be considered orthorhombic. On the other hand, the 103 cm-1 peak is clearly observed in both parallel and perpendicular configurations. Remarkably, the off-diagonal component of the Raman tensor of the 103 cm-1 peak showed an anti-symmetry that could not be realized within the known crystal structure of Bi2212. The implications of our findings are discussed.

[ $Bi_2Sr_2CaCu_2O{8+\delta}$ ] Intrinsic Josephson Junctions in a Parallel Magnetic Field

  • Lee, J.H.;Chong, Yon-Uk;Lee, Su-Youn;Khim, Z.G.
    • Progress in Superconductivity
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    • v.1 no.2
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    • pp.110-114
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    • 2000
  • We have investigated the Josephson vortex dynamics in $Bi_2Sr_2CaCu_2O{8+\delta}$ intrinsic Josephson junctions subjected to a magnetic field parallel to $CuO_2$ planes. We investigated mesas with $40\times40{\mu}m^2$ in size and containing 6 and 20. intrinsic junctions. The zero field I-V characteristics exhibited a typical hysteretic, multi-branched nature of the intrinsic Josephson effect. At high magnetic fields (H>1.5 T), I-V characteristics showed flux flow steps. The Swihart velocity obtained from this observation was about $4.2\times10^5$ m/s, which was the lowest mode electromagnetic wave velocity of N coupled stack. The experimental I-V curves fitted well into the simple model of Cherenkov radiation including Ohmic and non-linear dissipation terms. This suggests that the dissipation mechanism of Josephson vortex be due to both Cherenkov radiation and quasiparticle tunneling current.

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