• 제목/요약/키워드: $ReO_3$

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등온열처리와 냉각에 따른 $REBa_2Cu_3O_{7-x}$ (RE=Nd, Gd, Dy) 초전도체의 상변화 (Phase transformation of $REBa_2Cu_3O_{7-x}$ (RE=Nd, Gd, Dy) Superconductor during Continuous Cooling and Isothermal Heat Treatment)

  • 오용택;신동찬;한영희;성태현;정년호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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    • pp.42-45
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    • 2003
  • The phase transformation of $REBa_2Cu_3O_{7-x}$ (RE=Nd, Gd, Dy) was investigated using isothermal heat-treatment and continuous cooling in air. During continuous cooling, the $REBa_2Cu_3O_{7-x}$ (RE=123) superconducting phase with well-distributed $REBa_2Cu_3O_{7-x}$ (RE-211) was obtainde at a cooling rate of $0.001^{\circ}C$/s. Single phase RE-123 (Nd, Gd, Dy) was stable at $1050^{\circ}C$, $1050^{\circ}C$, and $950^{\circ}C$ during isothermal heat-treatment, respectively. Above these temperatures the RE-211 phase existed within the RE-123 grains. The RE-123, RE-211, $BaCu_2Od_2$, and CuO phases coexisted at $50^{\circ}C$ below the partial melting temperature for each respective rare-earth RE-123.

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화학 기상 증착법으로 제조한 ReMnO3(Re:Y, Ho, Er) 박막의 전기적 특성 (Electrical Properties of ReMnO3(Re:Y, Ho, Er) Thin Film Prepared by MOCVD Method)

  • 김응수;채정훈;강승구
    • 한국세라믹학회지
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    • 제39권12호
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    • pp.1128-1132
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    • 2002
  • MFS-FET(Metal-Ferroelectric-Semiconductor Field Effect Transistor) 구조의 비휘발성 기억소자용 $ReMnO_3$(Re:Y, Ho, Er) 박막을 금속 유기 화학 기상 증착법(MOCVD)으로 증착하였다. $ReMnO_3$ 박막을 Si(100) 기판 위에 700${\circ}C$-2시간 증착 시켜 결정화를 위해 대기 중에서 900${\circ}C$-1시간 열처리 시 육방정계(hexagonal) 단일상의 $ReMnO_3$ 박막을 형성하였다. 육방정계 단일상 구조에서 $ReMnO_3$ 박막의 강유전 특성은 c-축 배향성에 의존하였으며, c-축 배향성이 우수한 $YMnO_3$ 박막의 잔류 분극(Pr) 값은 105 nC/$cm^2$로 가장 우수하였다. 또한 누설 전류 밀도(leakage current density) 값은 미세구조의 결정립 크기에 의존하였으며, 결정립 크기가 100∼150 nm인 $YMnO_3$ 박막의 누설 전류 밀도 값은 인가전압 0.5 V에서 $10^{-8}$ A/$cm^2$을 나타내었다.

ReMnO3(Re:Ho, Er) 박막의 강유전성에 미치는 열처리 공정의 영향 (Effects of Thermal Heat Treatment Process on the Ferroelectric Properties of ReMnO3 (Re:Ho, Er) Thin Films)

  • 김응수;채정훈
    • 한국세라믹학회지
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    • 제42권11호
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    • pp.763-769
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    • 2005
  • Ferroelectric $ReMnO_3$(Re:Ho, Er) thin films were deposited on Si(100) substrate by Metal-Organic Chemical Vapor Deposition (MOCVD). Crystallinity and electric properties of $ReMnO_3$(Re:Ho, Er) thin films were investigated as a function of thermal heat treatment process, CHP (Conventional Heat-treatment Process) and RTP (Rapid Thermal Process). $ReMnO_3$(Re:Ho, Er) thin films prepared by RTP showed higher c-axis preferred orientation and homogeneous surface roughness than those prepared by CHP. The remnant polarization of ferroelectric hysteresis loop of $ReMnO_3$(Re:Ho, Er) thin films was strongly dependent on the c­axis preferred orientation of hexagonal single phase, and the leakage current characteristics of thin films were dependent on the homogeneity of grain size as well as surface roughness of thin films.

Luminescence properties of Eu3+ : RE2O3 [RE = Gd, Y, La] nanocrystallines prepared by solvothermal reaction method

  • Chung, Jong Won;Yang, Hyun Kyoung;Moon, Byung Kee;Choi, Byung Chun;Jeong, Jung Hyun;Kim, Kwang Ho
    • Journal of Ceramic Processing Research
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    • 제13권spc1호
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    • pp.6-9
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    • 2012
  • Eu3+-doped RE2O3 (RE = Gd, Y and La) phosphors were prepared by solvothermal reaction method and their crystalline structure, phase transformation and surface morphologies were investigated by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). The obtained RE2O3:Eu3+ phosphors are nanocrystalline-sized. The luminescence properties of Eu3+ ions in different host materials, namely, Gd2O3, Y2O3 and La2O3 have been investigated. PACS number: 32.50.+d, 78.55.-m, 81.40.Tv.

PMMA-HfOx 유-무기 하이브리드 저항변화 메모리 제작 (Fabrication of PMMA-HfOx Organic-Inorganic Hybrid Resistive Switching Memory)

  • 백일진;조원주
    • 한국전기전자재료학회논문지
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    • 제29권3호
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    • pp.135-140
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    • 2016
  • In this study, we developed the solution-processed PMMA-$HfO_x$ hybrid ReRAM devices to overcome the respective drawbacks of organic and inorganic materials. The performances of PMMA-$HfO_x$ hybrid ReRAM were compared to those of PMMA- and $HfO_x$-based ReRAMs. Bipolar resistive switching behavior was observed from these ReRAMs. The PMMA-$HfO_x$ hybrid ReRAMs showed a larger operation voltage margin and memory window than PMMA-based and $HfO_x$-based ReRAMs. The reliability and electrical instability of ReRAMs were remarkably improved by blending the $HfO_x$ into PMMA. An Ohmic conduction path was commonly generated in the LRS (low resistance state). In HRS (high resistance state), the PMMA-based ReRAM showed SCLC (space charge limited conduction). the PMMA-$HfO_x$ hybrid ReRAM and $HfO_x$-based ReRAM revealed the Pool-Frenkel conduction. As a result of flexibility test, serious defects were generated in $HfO_x$ film deposited on PI (polyimide) substrate. On the other hand, the PMMA and PMMA-$HfO_x$ films showed an excellent flexibility without defect generation.

RE3+원소가 첨가된 YBCO고온초전도체의 용융성장 및 초전도 특성 (Melt Textured Growth and Superconducting Properties of RE3+ Elements Doped YBCO Superconductors)

  • 김소정
    • 한국전기전자재료학회논문지
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    • 제16권3호
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    • pp.231-237
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    • 2003
  • RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.

$Bi_2O_3$ 첨가에 따른 (Na,K,Li)$NbO_3$계 무연 압전 세라믹스의 압전특성 (The Piezoelectrc properties of (Na,K)$NbO_3$-system Pb-free Piezoelectric Ceramics with $Bi_2O_3$ Addition)

  • 류성림;이호일;배세환;김주현;김용주;서상현
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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    • pp.216-217
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    • 2005
  • In this paper, in order to develop Pb-free piezoelectric ceramics, $(Li_{0.05}Na_{0.57}K_{0.38})NbO_3$ ceramic was fabricated with the variation of $Bi_2O_3$ addition. Piezoelectric properties of the ceramic were varied with the amount of $Bi_2O_3$ addition and showed the maximum kp value at.0.2 wt% $Bi_2O_3$ addition. Qm of $Bi_2O_3$ added ceramics showed lower values than the non-added ceramics, however, the kp was increased by the addition of $Bi_2O_3$ up to 0.2 wt%. At the sintering temperature of 1110$^{\circ}C$ and the calcination temperature of 850$^{\circ}C$, the optimal values of density=4.52g/$cm^3$, kp=0.47, $\varepsilon_r$=400 were obtained.

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Sm을 첨가한 BaTiO3계의 재산화 온도 및 시간에 따른 PTC 특성 변화 (Effects of the Re-oxidation Temperature and Time on the PTC Properties of Sm-doped BaTiO3)

  • 정용근;최성철
    • 한국세라믹학회지
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    • 제46권3호
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    • pp.330-335
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    • 2009
  • We investigated the effects of the re-oxidation temperature and time on the positive temperature coefficient (PTC) of resistivity characteristics of Sm-doped $BaTiO_3$ sintered at $1200{\sim}1260^{\circ}C$ for 2 h in a reducing atmosphere (3% $H_2/N_2$), followed by re-oxidization processes in air, in which re-oxidization temperature and time were $600{\sim}1000^{\circ}C$ and $1{\sim}10$h, respectively. The result reveals that Smdoped (Ba,Ca)$TiO_3$ ceramics fired in a reducing atmosphere exhibit low PTC characteristics, whereas the sample re-oxidized at $800^{\circ}C$ for 1 h in air exhibit pronounced PTC characteristics. The room-temperature resistivity and jumping characteristics of resistivity (${\rho}_{max}/{\rho}25^{\circ}C$) decrease with Sm contents. The PTC characteristics with reoxidization time at $800^{\circ}C$ have improved about $2{\sim}3$ orders of magnitude whereas differed according to the sintering temperature. The 0.7 at% Sm-doped (Ba,Ca)$TiO_3$ samples reveal the best PTC characteristics in the present range of formula and processes.