• 제목/요약/키워드: Bi-2201

검색결과 79건 처리시간 0.029초

Phase transition of (Bi, Pb)-2223 superconductor induced by Fe3O4 addition

  • Ko, Y.J.;Oh, J.Y.;Song, C.Y.;Yang, D.S.;Tran, D.H.;Kang, B.
    • 한국초전도ㆍ저온공학회논문지
    • /
    • 제21권4호
    • /
    • pp.1-5
    • /
    • 2019
  • We investigated the effect of Fe3O4 addition on the critical temperature of (Bi, Pb)-2223 polycrystalline samples. Bi1.6Pb0.4Sr2Ca2Cu3O10+δ + x wt. % Fe3O4 (x = 0.0, 0.2, 0.4, 0.6, and 0.8) samples were prepared by using a solid-state reaction method. The analysis of X-ray diffraction data indicates that as Fe3O4 is added, dominant phase of the sample changes from Bi-2223 to Bi-2212 with an increasing Bi-2201 phase. The transition temperature of the samples drastically decreased with the Fe3O4 addition. The resistance data of samples with x = 0.2 and 0.4 showed a double transition indicating a coexistence of Bi-2223 and Bi-2212 phase while the samples with x = 0.6 and 0.8 showed a single transition with a semiconducting behavior. This phase transition may originate from changes in local structure of the Bi-2223 system by Fe3O4 addition. Analysis of the pair distribution function of the Cu-O pair in the CuO2 plane calculated from extended X-ray absorption fine structure data revealed that the oxygen coordination of copper ion changes from CuO4 planar type (x = 0.0 - 0.4) to CuO5 pyramidal type (x = 0.6, 0.8). The correlated Debye-Waller factor, providing information on the atomic disorder within the CuO2 plane, shows an inverse relation to the coordination number. These results indicate that addition of Fe3O4 changes the oxygen distribution around Cu in the CuO2 plane, causing a phase transition from Bi-2223 to more stable Bi-2212/Bi-2201 phases.

순차 스퍼터 법과 증발 법으로 제작한 박막의 특성 (Characteristics of Thin Films Fabricated by Using the Layer-by-Layer Sputtering and Evaporation Method)

  • 천민우;박용필;김정호
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
    • /
    • pp.571-574
    • /
    • 2003
  • The thin films fabricated by using the layer-by-layer sputtering was compared with the thin film fabricated by using the evaporation method. Re-evaporation in the form of Bi atoms or $Bi_2O_3$ molecules easily bring out the deficiency of Bi atoms in thin film due to the long sputtering time of the layer-by-layer deposition. On the other hand, the respective atom numbers corresponding to BiSrCaCuO phase is concurrently supplied on the film surface in the evaporation deposition process and leads to BiSrCaCuO phase formation. 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.

  • PDF

SI(superconductor-insulator) Transitions in Bi-superconducting Mixed Crystal Thin Films

  • Park, No-Bong;Yang, Sung-Ho;Park, Yong-Pil
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2002년도 하계학술대회 논문집
    • /
    • pp.486-489
    • /
    • 2002
  • Temperature(T) dependence of the sheet resistance( $R_{$\square$}$) has been investigated on the c-axis oriented thin films of the (Bi2212/Bi2201) mixed crystal with different molar fractions. The $R_{$\square$}$-T superconducting characteristic deteriorated with reduction of the Bi2212 fraction, and almost disappears at 48 mol% where a superconductor-to-insulator transition took place, with the resistance on the normal state, RN, reaching 4.l㏀ at 80 K. This $R_{N}$ value is close to the universal quantum number, h/(2e)$^2$≡6.5㏀ predicted by the Kosterlitz-Thouless(KT) transition theory. The $R_{$\square$}$-T characteristics of the 48 mol% thin film can be elucidated as a competitive process of KT transition brought about by charge or vortex in the two-dimensional layer structure.e.

  • PDF

초전도 박막의 에피택셜 성장에 관한 연구 (A Study on the Epitaxial Growth of Superconducting Thin Film)

  • 이희갑;박용필;김귀열
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
    • /
    • pp.208-211
    • /
    • 2002
  • $Bi_2Sr_2CuO_x$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

  • PDF

순차 스퍼터 법에 의한 BSCCO 박막의 특성 (Characteristics of BSCCO Thin Film by Layer-by-layer Deposition)

  • 이희갑;박용필;김귀열;오금곤;최운식;조춘남
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
    • /
    • pp.281-283
    • /
    • 2001
  • $Bi_{2}Sr_{2}CuO_{x}$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion bearn sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition. two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit. then three dimensional growth takes place. Since Cu element is the most difficult to oxidize. only Sr and Bi react with each other predominantly. and forms a buffer layer on the substrate in an amorphous-like structure. which is changed to $SrBi_{2}O_{4}$ by in-situ anneal.

  • PDF

순차 스퍼터 법에 의한 BSCCO 박막의 특성 (Characteristics of BSCCO Thin Film by Layer-by-layer Deposition)

  • 이희갑;박용필;김귀열;오금곤;최운식;조춘남
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2001년도 추계학술대회 논문집
    • /
    • pp.281-283
    • /
    • 2001
  • Bi$_2$Sr$_2$CuO$\_$x/(Bi-2201) thin films were fabricated layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to SrBi$_2$O$_4$ by in-situ anneal.

  • PDF

페러데이 컵을 이용한 초전도 박막의 특성 (Characteristic of Superconducting Thin Films Fabricated by Using the Faraday Cup)

  • 양승호;박용필
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
    • /
    • pp.583-586
    • /
    • 2003
  • BiSrCaCuO superconducting thin films have been fabricated by co-deposition using the faraday cup. Despite setting the composition of thin film Bi2212, Bi(2201, 2212, 2223) phase were appeared. It was confirmed the obtained field of stabilizing phase was represented in the diagonal direction of the right below end in the Arrhenius plot of temperature of the substrate and $PO_3$, and it was distributed in the rezone.

  • PDF

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

  • 천민우;박용필;김정호
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
    • /
    • pp.1208-1211
    • /
    • 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.

  • PDF

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

  • 박용필;이준웅
    • E2M - 전기 전자와 첨단 소재
    • /
    • 제10권5호
    • /
    • pp.425-433
    • /
    • 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.

  • PDF

Analysis of Bi-Superconducting Thin Films Fabricated by Using the Layer by Layer Deposition and Evaporation Deposition Method

  • Yang, Seung-Ho;Cheon, Min-Woo;Lee, Ho-Shik;Park, Yong-Pil
    • 한국정보통신학회:학술대회논문집
    • /
    • 한국해양정보통신학회 2007년도 춘계종합학술대회
    • /
    • pp.517-520
    • /
    • 2007
  • The BSCCO thin film fabricated by using the layer by layer deposition method was compared with the BSCCO thin film fabricated by using the evaporation method. Reevaporation in the form of Bi atoms or $Bi_2O_3$molecules easily bring out the deficiency of Bi atoms in thin film due to the long sputtering time of the layer by layer deposition. On the other hand, the respective atom numbers corresponding to BSCCO phase is concurrently supplied on the film surface in the evaporation deposition process and leads to BSCCO phase formation. 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.

  • PDF