• Title/Summary/Keyword: 2212 phase

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Phase Diagram of Single Crystal in Bi System (Bi계 초전도 박막의 단결정 생성영역)

  • Cheon, Min-Woo;Kim, Tae-Gon;Park, Yong-Pil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.327-328
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    • 2005
  • Bi-system thin films are prepared by ion beam sputtering technique. Three phases of Bi-2201, Bi-2212 and Bi-2223 appear as stable ones in spite of the conditions for thin film fabrication of Bi-2212 and Bi-2223 compositions, depending on substrate temperature($T_{sub}$) and ozone pressure($PO_3$). It is found out that these phases show similar $T_{sub}$ and $PO_3$ dependence, and that the stable regions of these phases are limited within very narrow temperature.

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Analysis of Thermodynamics for Formation of Single Phase in $Bi_2Sr_2Ca_nCu_{n+1}O_x$ Thin Films ($Bi_2Sr_2Ca_nCu_{n+1}O_x$ 박막의 단상 형성을 위한 열역학 해석)

  • Cheon, Min-Woo;Park, Yong-Pil;Kim, Jeong-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.1208-1211
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    • 2003
  • High quality $Bi_2Sr_2Ca_nCu_{n+1}O_x$ superconducting thin films fabricated by using the evaporation method at various substrate temperatures, $T_{sub}$, and ozone gas pressures, $pO_3$. The correlation diagrams of the $Bi_2Sr_2Ca_nCu_{n+1}O_x$ phases with $T_{sub}$ and $pO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 as well as Bi2212 phases come out as stable phases depending on $T_{sub}$ and $pO_3$. From these results, the thermodynamic evaluation of ${\Delta}H$ and ${\Delta}S$, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase, was performed.

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Comparison between Superconducting Thin Films Fabricated by Using the Sputtering and the Evaporation Method (스퍼터링 법과 증발 법으로 제작한 초전도 박막의 비교)

  • Cheon, Min-Woo;Park, No-Bong;Yang, Sung-Ho;Park, Yong-Pil;Kim, Hye-Jeong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.04a
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    • pp.39-42
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    • 2004
  • The $Bi_2Sr_2Ca_nCu_{n+1}O_x$ superconducting thin film fabricated by using the sputtering method was compared with the $Bi_2Sr_2Ca_nCu_{n+1}O_x$ superconducting thin film fabricated by using the evaporation method. In doing the ultra-low deposition because each element can exist on the substrate surface, both the sputtering method and the evaporation method could easily fabricate single phase of the Bi2212 phase. Also, it is cofirmed that by optimizing the deposition condition, each single phase of the Bi2201 phase and the Bi2212 phase can be fabricated, the sticking coefficient of Bi element is clearly related to the changing of substrate temperature and the formation of the Bi2212 phase.

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Annealing Characteristic of Bi-2212 thick Films on Y2l1 substrate (Y211 기판 위의 Bi-2212 후막의 후열처리 특성)

  • Kang, Hyeong-Gon;Lim, Sung-Hun;Chong, Dong-Chul;Lim, Sung-Woo;Han, Byoung-Sung
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.296-299
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    • 1999
  • Bi$_2Sr_2CaCu_2O$(Bi-2212) thick films were fabricated on Y2l1 substrate by screen printing method. And the samples were annealed in various atmospheres, respectively. Though samples had many voids, the sample annealed in N$_2$ ; O$_2$ = 1:0 atmosphere and the sample in N$_2$ : O$_2$ = 0:1 showed some Bi 2212 low phase in comparison to other samples. The thickness of Bi-2212 on Y2ll substrates was about 20 ${\mu}$m.

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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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Effect of after annealing on critical current of Bi-2212 HTS round wires (후열처리 조건에 따른 Bi-2212 고온 초전도선의 임계전류 특성 변화)

  • Ha, Dong-Woo;Kim, Sang-Chul;Oh, Jae-Gn;Oh, Sang-Soo;Ha, Hong-Soo;Song, Gyung-Jung;Goh, Rak-Kil;Kim, Ho-Sup;Kim, Tae-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.06a
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    • pp.91-92
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    • 2006
  • The important merit of Bi-2212/Ag wire is to apply cable as round wire state. Bi-2212 high Tc superconducting wires were fabricated in order to apply Rutherford cable near the future. Various Ag ratio from 0.22 to 0.42 of Ag tubes for PID (powder-In-Tube) process were used to investigate the workability and to prevent breakage of filaments during drawing. In order to find proper heat treatment condition, we investigated micro-structure of Bi-2212/Ag wires by using differential thermal analysis, XRD and SEM. The effect of atmosphere on the peritectic decomposition temperature of precursor was investigated. The shape of grain was observed by SEM to investigate Bi-2212 phase formation in filaments. The higher of Ag ratio of mono filament had the higher critical current density, Jc. The wire with 0.42 of Ag ratio showed 7,886 A/cm2 of Jc at 77K.

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c-axis Tunneling in Intercalated Bi$_2Sr_2CaCu_2O_{8+x}$ Single Crystals

  • Lee, Min-Hyea;Chang, Hyun-Sik;Doh, Yong-Joo;Lee, Hu-Jong;Lee, Woo;Choy, Jin-Ho
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.260-260
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    • 1999
  • We compared c-axis tunneling characteristics of small stacked intrinsic Josephson junctions prepared on the surface of pristine, I-, and HgI$_2$-intercalated Bi$_2Sr_2CaCu_2O_{8+x}$ (Bi2212) single crystals. The R(T) curves are almost metallic in I-Bi2212 specimens, but semiconducting in HgI$_2$-Bi2212 ones.· The transition temperatures were 82.0 K, 73.0 K, and 76.8 K for pristine Bi2212, I-Bi2212, and HgI2-Bi2212 specimens, respectively, consistent with p-T$_c$ phase diagram. Current-voltage (IV) characteristics of both kinds of specimens show multiple quasiparticle branches with well developed gap features, indicating Josephson coupling is established between neighboring CuO$_2$ planes. The critical current I$_c$ of I-Bi2212 is almost the same as of that of pristine crystals, but I$_c$ is much reduced in Hgl$_2$-Bi2212. In spite of expanded interlayer distances, the interlayer coupling is not significantly affected in I-Bi2212due to holes generated by iodine atoms. The coupling in HgI$_2$-Bi2212 is, however, weakened due to inertness of HgI$_2$ molecules and the expansion of interlayer distance. Relation between the superconducting transition temperature T$_c$ and the critical current I$_c$ seems to contradict Anderson's interlayer-pair-tunneling theory but agree with a modified version of it.

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Characteristics of Co-deposition for Bi-superconductor Thin Film Using Ion Beam Sputtering Method (IBS 법으로 제작한 Bi 계 초전도 박막의 동시 증착 특성)

  • 박용필;이준웅
    • Electrical & Electronic Materials
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    • v.10 no.5
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    • pp.425-433
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    • 1997
  • BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 82$0^{\circ}C$ and the highly condensed ozone gas pressure(PO$_3$) in vacuum chamber was varied between 2.0$\times$10$^{-6}$ and 2.3$\times$10$^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795$^{\circ}C$ and single phase of Bi 2201 existed in the lower region than 785$^{\circ}C$. Whereas, PO$_3$dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with T$_{c}$(onset) of about 90 K and T$_{c}$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as CaCuO$_2$was observed in all of the obtained films.lms.

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Study on the deposition Characteristics of Bi Thin Film (Bi 박막의 성막 특성에 관한 연구)

  • Lee, Hee-Kab;Park, Yong-Pil;Lee, Joon-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.1071-1074
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    • 2002
  • This paper presents Bi thin films have been fabricated by atomic layer-by-layer deposition and co-deposition at an IBS method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and $820^{\circ}C$ and the highly condensed ozone gas pressure$(PO_3)$ in vacuum chamber was varied between $2.0{\times}10^{-6}$ and $2.3{\times}10^{-5}Torr$. Bi 2212 phase appeared in the temperature range of 750 and $795^{\circ}C$: and single phase of Bi 2201 existed in the lower region than $785^{\circ}C$. Whereas, $PO_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.

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