• 제목/요약/키워드: perovskite/pyrochlore phase

검색결과 72건 처리시간 0.019초

졸-겔법으로 백금 기판위에 제조된 PLZT 박막의 구조적, 전기적 특성변화 (Structural and Electrical Characteristics of Ferroelectric PLZT Thin Film Prepared on Pt Substrate by Sol-Gel Route)

  • 오영제;김태송;정형진
    • 한국세라믹학회지
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    • 제31권2호
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    • pp.171-176
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    • 1994
  • The spin-casted PLZT(9/65/35) thin films through polymeric sol-gel process were prepared on Pt substrate. The crack-free, uniform and dense films were obtained by post-annealing at the temperature between 35$0^{\circ}C$ and $700^{\circ}C$. The composite structure mixed together with large grains called "rosette" and surrounding small grains were observed on the films annealed over $600^{\circ}C$. Pyrochlore phase was completely changed to perovskite phase above $600^{\circ}C$ with the increase of annealing temperature. Dielectric constant (k) was larger with the increase of film thickness and annealing temperature. from the measurements of dielectric constant as a function of measuring temperature, it was also observed that Curie temperature was shifted to higher temperature with the increase of film thickness and annealing temperature. The pyroelectric coefficient(P) of 10 times coated film annealed at $700^{\circ}C$ was 65 $\mu$C/$\textrm{cm}^2$.K.$.K.

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PZT-PNN-PZN계 세라믹스의 물리적 성질 (Physical Properties of PZT-PNN-PZN Ceramics)

  • 정수태;조상희;이우일
    • 한국세라믹학회지
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    • 제29권3호
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    • pp.183-188
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    • 1992
  • The physical properties of 0.5PZT-0.5(PNN-PZN) ceramics have been investigated as a function of PZN content. A pyrochlore phase exists in the range of 600∼850$^{\circ}C$ and a stable perovskite phase appears above 850$^{\circ}C$. The piezoelectric properties (except electro-mechanical coupling factor) of 0.5PZT-0.5(PNN-PZN) ceramics showed almost linear relationships of PZN content within the range of 0.5PZT-0.5PNN system and 0.5PZT-0.5PZN system. The temperature dependence of piezoelectric constant, the electric field dependence of induced strain and a bend strength are improved by addition of PZN.

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Pb(Zr, Ti)$O_3$ 박막에서 결정립 크기 포화 현상에 관한 연구 (A Study on the Saturation of Grain Size in Pb(Zr, Ti)$O_3$ Thin Films)

  • 이장식;김찬수;주승기
    • 한국세라믹학회지
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    • 제37권6호
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    • pp.530-536
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    • 2000
  • During the grain growth of the PZT thin films by selective nucleation method using PZT seed, it was found that the grain size was saturated with the annealing temperature. The saturation of grain size was analyzed by the interfacial energy which appeared during the crystallization. The factors affecting the saturation of grain size were found to be the interfacial energy between perovskite phase and pyrochlore phase, and PZT thin film and the bottom Pt electrode. When the ion damage was introduced to the grain-size saturated PZT thin films, further lateral growth was observed. Pt bottom electrode thickness was changed to control the interfacial energy between the PZT thin film and the Pt bottom electrode. When Pt thickness was increased, the grain size was also increased, because the lattice parameter of Pt films was increased with the thickness of the Pt films. The incubation time of nucleation was increased with the amount of the ion damage on the Pt films.

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소결조제 Li2CO3 첨가에 따른 PZW-PMN-PZT 압전 세라믹의 압전 및 유전 특성 (Piezoelectric and Dielectric Properties of PZW-PMN-PZT Piezoelectric Ceramic according to Sintering Aid Li2CO3 Addition)

  • 이갑수;이일하;류주현;류성림
    • 한국전기전자재료학회논문지
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    • 제20권12호
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    • pp.1034-1038
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    • 2007
  • In order to develop the composition ceramics capable of being sintered at low temperature with high piezoelectric properties for multilayer piezoelectric actuator application, PZW-PMN-PZT system ceramics were manufactured according to sintering aid $Li_2CO_3$ addition and their microstructural, dielectric and piezoelectric properties were investigated. The crystal structure of the specimens showed a perovskite phase and no pyrochlore or other second phase was detected. At the sintering temperature of $900\;^{\circ}C,\;0.2\;wt%Li_2CO_3$ added specimen showed a optimum values of kp = 0.562, $d_{33}\;=\;360\;pC/N$ and Qm = 1184, respectively.

Electrical properties of (Na0.5K0.5)NbO3-BiTiO3 ceramics with the variation of sintering temperature

  • Lee, Tae-Ho;Lee, Sung-Gap
    • Journal of Ceramic Processing Research
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    • 제13권spc2호
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    • pp.174-176
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    • 2012
  • Piezoelectric 0.93(Na0.5K0.5)NbO3-0.07BiTiO3 (NKN-BTO) ceramics were fabricated by the mixed-oxide method and their structural and dielectric properties was investigated with the variation of sintering temperature. All specimens were crystallized in the perovskite single phase without any formation of a second phase such as pyrochlore. The average grain size of the NKN-BTO specimen sintered at 1130 ℃ is 0.32 ㎛. The specimen sintered at 1100 ℃ showed the highest relative density of 98%. Electromechanical coupling factor, relative dielectric constant and dielectric loss of the NKN-BTO specimens sintered at 1110 ℃ were 0.31, 1222 and 0.02, respectively. Curie temperature of the specimen sintered at 1110 ℃ was 445 ℃.

초임계 유체법을 이용한 Pb(Fe1/2Nb1/2)O3분말 제조 (Preparation of Pb(Fe1/2Nb1/2)O3 Powders by Supercritical Fluid Method)

  • 임대영;김병규;최근목;홍석형;김태훈
    • 한국세라믹학회지
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    • 제39권6호
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    • pp.566-569
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    • 2002
  • 일반적으로 Pb-계 복합 perovskite형 산화물들은 그 제조과정에서 중간상으로 알려진 pyrochore상을 통하여 최종적으로 합성된다. 본 연구에서는 Pb(Fe$_{1}$2/Nb$_{1}$2/)O$_3$를 대상으로 하여 고유전율, 고순도, 입자크기 및 저온 소결에 알맞은 Pb(Fe$_{1}$2/Nb$_{1}$2/)O$_3$분말을 초임계 유체의 장점과 autoclave내의 분리 반응 실험으로 285$^{\circ}C$,7.2MPa의 조건하에서 제조하였고, 제조되어진 분말들의 제반 특성들에 대하여 조사하였다.

루테늄 전극위에 증착된 PZT 박막의 전기적 및 강유전 특성 (The Electric and Ferroelectric of Pb(Zr0.52Ti0.48)O3 Thin Films Deposited on Ruthenium Electrodes)

  • 황현석;유영식;임윤식;강현일
    • 전기학회논문지P
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    • 제63권1호
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    • pp.46-49
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    • 2014
  • $Pb(Zr_{0.52}Ti_{0.48})O_3(PZT)$ thin films deposited on $Ru/RuO_2$ bottom electrode that grown for in-situ progress used rf magnetron sputtering method. We investigated the dependence of the crystalline and electrical properties in the way of capacitors PZT thin films. Our results show that all PZT films indicated polycrystalline perovskite structure with preferred orientation (110) and no pyrochlore phase is observed. The electric properties of the Ru improved with increasing Ru thin films thickness. A well-fabricated Ru/PZT/Ru (100 nm) /$RuO_2$ capacitor showed a leakage current density in the order of $2.03{\times}10^{-7}$ $A/cm^2$ as a 50 kV/cm, a remnant polarization (Pr) of 9.22 ${\mu}C/cm^2$, and a coercive field (-EC) of -32.22 kV/cm. The results show that $Ru/Ru/RuO_2$ bottom electrodes are expected to reduce the degradation ferroelectric fatigue and excellent ferroelectric properties.

Sol-Gel법을 이용한 $PbTiO_3$ 박막의 결정화에 관한 연구 (Study on crystallization of $PbTiO_3$ thin films by the Sol-Gel method)

  • Kyu Seog Hwang;Byung Wan Yoo;Byung Hoon Kim
    • 한국결정성장학회지
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    • 제4권2호
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    • pp.199-209
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    • 1994
  • Titanium tetra iso-propoxide와 Lead acetate trihydrate를 출발물질로 사용하여 제조한 졸을 현미경용 soda-lime-silica 슬라이드 유리, Si-Wafer 및 Sapphire 기판 위에 Dip-coating법으로 박막을 제조하였으며, 안정한 졸을 얻기 위하여 Acetylacetone을 첨가하였다. 졸의 점도, 조성등의 영향을 조사하였고, 조성변화, 막의 두께 변화, 열처리 온도에 따른 가시영역에서의 투과율과 굴절율 및 IR Spectra를 측정하였으며, $PbTiO_3$ 박막의 결정 생성 유무를 XPD로 검토하였다. 또하 EDX로 슬라이드 유리에서 박막으로의 확산 유무를 조사하였다. 제조된 졸은 20일동안 침전없는 안정한 상태를 유지하였다. 가시영역에서의 투과율은 열처리온도와 막의 두께가 증가함에 따라 감소하였고, flat한 투과특성을 나타내었다. 슬라이드 유리 위에 코팅한 $PbTiO_3$ 박막은 $600^{\circ}C$에서 열처리한 경우 Pyrochlore형이 나타났고, Si-Wafer와 Sapphire 기판 위에 코팅할 경우에는 $600^{\circ}C$에서 Pyrochlore형이 나타나기 시작하였으며, 열처리 온도가 높아짐에 따라 $800^{\circ}C$에서 $PbTi_3O_7$상이 나타났다.

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MgO가 과잉첨가된 $30Pb(Mg_{1/3}Nb_{2/3})O_3-20PbTiO_3-50Pb(Mg_{1/2}W_{1/2})O_3$계 세라믹스의 미세구조와 유전특성 (Microstructure and Dielectric Properties in $30Pb(Mg_{1/3}Nb_{2/3})O_3-20PbTiO_3-50Pb(Mg_{1/2}W_{1/2})O_3$ Ceramics with Excess MgO Addition)

  • 길영배;이응상
    • 한국세라믹학회지
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    • 제34권1호
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    • pp.31-36
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    • 1997
  • 유전율이 높고 온도안정성이우수하다고 알려져 있는 Pb(Mg1/3Nb2/3)O3-PbTiO3-Pb(Mg1/2W1/2)O3 계 세라믹스를 산화물혼합법 및 precursor방법으로 제조함에 있어 과잉 MgO의 첨가에 따른 미세구조와 유전특성의 변화에 대하여 조사하였다. MgO를 5mol%이상 과잉첨가하여 100$0^{\circ}C$에 소결한 시편의 유전율은 5000이상이고, -55$^{\circ}C$에서 1$25^{\circ}C$범위에서 변화율은 +25%에서 -5$0^{\circ}C$ 정도를 나타냈다. XRD 분석결과 perovskite상과 Pb2WO5 결정이 주된상이었으며, 소결온도 및 MgO 첨가량이 증가함에 따라 cubic pyrochlore상인 Pb3Nb4O13와 PbWO4는 감소하였다. SEM에 의한 미세구조의 관찰에서 MgO첨가량이 증가함에 따라 결정성장이 촉진되는 것을 알 수 있었으며 이것이 소결온도 증가에 따른 pyrochlore상의 감소와 함께 유전율을 증가시키는 원인이었다. BSE관찰에서 화학성분 분포의 불균일성이 나타났으며, 각각의 소결온도에서 생성되는 결정상과 함께 유전율의 온도의존성을 완만하게 만드는 원인임을 알 수 있었다.

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Pb($Zn_{1/3}Nb_{2/3}O_3-PbTiO_3-BaTiO_3$) System의 미세구조와 전기적 물성에 관한 연구 (A Study on Microstructure and Electrical Properties in Pb($Zn_{1/3}Nb_{2/3}O_3-PbTiO_3-BaTiO_3$ System)

  • 이응상;이정우
    • 한국세라믹학회지
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    • 제29권9호
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    • pp.675-680
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    • 1992
  • The purpose of this investigation was to study the stability of perovskite structure, the variation of electrical properties and a microstructure with varing amount of PbTiO3 additive in PZN-PT-BT system. The results are as follows: 1. The pyrochlore phase was reduced as the amount of PbTiO3 additive was increased and completely eliminated at 0.15PT in PZN-PT-BT system. 2. The aging rate was increased in proportion to tetragonality because the internal stress was increased in proportion to tetragonality. 3. On increasing the amount of PbTiO3 additive, the Curie temperature was increased in proportion to tetragonality. 4. As the amount of PT in the composition increase, the variation of dielectric constant was sharpened and the diffuseness of the transition decreased.

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