• 제목/요약/키워드: Bi-layered Ferroelectrics

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비스무스 층구조형 페로브스카이트 SrBi2Nb2O9 강유전체의 이온 치환 효과 (Ionic Doping Effect in Bi-layered Perovskite SrBi2Nb2O9 Ferroelectrics)

  • 박성은;조정아;송태권;김명호;김상수;이호섭
    • 한국재료학회지
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    • 제13권12호
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    • pp.846-849
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    • 2003
  • Doping effect of various ions in Bi-layered ferroelectric $SrBi_2$$Nb_2$$O_{9}$ (SBN) ceramics was studied. Undoped SBN ceramic and SBN ceramics doped with $Ba^{2+}$, $Pb^{2+}$,$ Ca^{2+}$ , $Bi^{3+}$ , $La^{3+}$ , $Ti^{4+}$ , $Mo^{6+}$ , and $W^{6+}$ ions were made by a solid state reaction. Dielectric constants were measured with temperature. Ferroelectric transition temperature decreased with $Pb^{2+}$ , $Ba^{2+}$ , $La^{3+}$ doping, but the transition temperature increased with $Ca^{2+}$ , $Bi^{3+}$ , $Ti^{4+}$, $Mo^{6+}$ , or$ W^{6+}$ ionic doping. These results show that the ion size plays an important role in the ferroelectricity of SBN ceramic.

Fabrication of Nd-Substituted Bi4Ti3O12 Thin Films by Metal Organic Chemical Vapor Deposition and Their Ferroelectrical Characterization

  • Kim, Hyoeng-Ki;Kang, Dong-Kyun;Kim, Byong-Ho
    • 한국세라믹학회지
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    • 제42권4호
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    • pp.219-223
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    • 2005
  • A promising capacitor, which has conformable step coverage and good uniformity of thickness and composition, is needed to manufacture high-density non-volatile FeRAM capacitors with a stacked cell structure. In this study, ferroelectric $Bi_{3.61}Nd_{0.39}Ti_3O_{12}$ (BNdT) thin films were prepared on $Pt(111)/TiO_2/SiO_2/Si$ substrates by the liquid delivery system MOCVD method. In these experiments, $Bi(ph)_{3}$, $Nd(TMHD)\_{3}$ and $Ti(O^iPr)_{2}(TMHD)_{2}$ were used as the precursors and were dissolved in n-butyl acetate. The BNdT thin films were deposited at a substrate temperature and reactor pressure of approximately $600^{\circ}C$ and 4.8 Torr, respectively. The microstructure of the layered perovskite phase was observed by XRD and SEM. The remanent polarization value (2Pr) of the BNdT thin film was $31.67\;{\mu}C/cm^{2}$ at an applied voltage of 5 V.

Properties of $Sr_{0.8}Bi_{2.3}{(Ta_{1-x}Nb_{x})}_{2}O_{9+{\alpha}}$ Thin Films

  • Park, Sang-Jun;Jang, Gun-Eik
    • Transactions on Electrical and Electronic Materials
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    • 제1권1호
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    • pp.22-25
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    • 2000
  • Polycrystalline SBTN layered ferroelectric thin film with various Nb mole ratios were prepared by sol-gel method Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperature and characterized in terms of phase and microstructure. The films were crystallized with a high (105) diffraction intensity and had rodike structure, SBTN films fired at 800$^{circ}C$ revealed standard hysteresis loops with no fatigue for up to 10$^{10}$ cycles. At an applied voltage of 5V the dielectric constant($varepsilon$) , dissipation factor (tan $delta$), remanent polarization(ZPr) and coercive field(Ec) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$) $O_{9+}$$alpha$/ thin film(x=0.1) prepared on Pt/ $SiO_2$/Si (100) were about 277.7, 0.042, 3.74$mu$C/$textrm{cm}^2$, and 24.8kv/cm respectively.ly.y. respectively.ly.y.y..

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