• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.893-896
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• 2000

The SrBi$_2$Ta$_2$O$\sub$9/(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO$_2$/SiO$_2$/Si) using RF sputtering method. The SBT thin films deposited on substrate at 400-500[$^{\circ}C$]. SBT thin film deposited on Pt-coated electrodes have the cubic perovskite structure and polycrystalline state. With increasing annealing temperature from 600[$^{\circ}C$] to 850[$^{\circ}C$], flourite Phase was crystalized to 650[$^{\circ}C$] and Bi-layered perovskite phase was crystalized above 700[$^{\circ}C$]. The maximum remanent polarization is 11.73 ${\mu}$C/cm$^2$at 500[$^{\circ}C$] of substrate temperature and 750[$^{\circ}C$] annealing temperature for 30min.

• New & Renewable Energy
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• v.18 no.2
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• pp.40-49
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• 2022

In this study, the phase and electrochemical properties of Co and Ti substituted layered perovskites SmBaCo_2-xTi_xO_5+d (x=0.5, 0.7, 1.0, 1.1, 1.3, and 1.5) were analyzed, and their application as electrodes in solid oxide fuel cells (SOFCs) were evaluated. After calcination at 1300℃ for 6 h, a single phase was observed for two compositions of the SmBaCo_2-xTi_xO_5+d oxide system, SmBaCoTiO_5+d (x=1.0) and SmBaCo_0.9Ti_1.1O_5+d (x=1.1). However, the phases of SmBaCoTiO_5+d (SBCTO) and SmTiO₃ coexisted for compositions with x≥1.3 (Ti content). In contrast, for compositions of x≤0.7, the SmBaCo₂O_5+d phase was observed instead of the SmTiO₃ phase. To evaluate the applicability of these materials as SOFC electrodes, the electrical conductivities were measured under various atmospheres (air, N₂, and H₂). SBCTO exhibited stable semi-conductor electrical conductivity behavior in an air and N₂ atmosphere. However, SBCTO showed insulator behavior at temperatures above 600℃ in a H₂ atmosphere. Therefore, SBCTO may only be used as cathode materials. Moreover, SBCTO had an area specific resistance (ASR) value of 0.140 Ω·cm² at 750℃.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.623-627
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• 2004

Phase formation and electrical conduction behavior of Ba-doped LaBaGa $O_4$ layered perovskite were studied. Orthorhombic single phase of $K_2$Ni $F_4$-type structure was observed for the composition range of 0$\leq$x$\leq$0.2 in the La$\_$1＋x/Ba$\_$1＋x/Ga $O_4$$\_$4-$\delta$/ system by X-ray analysis. In the dry atmosphere, La$\_$0.8/Ba$\_$1.2/Ga$\_$3.9/ exhibited mixed conduction of oxygen ion and hole (p-type) at high p( $O_2$). However, in water vapor containing atmosphere, it showed proton conduction due to the incorporation of water into oxygen vacancies. As the temperature decreased, the contribution of proton conductivity to the total conduction increased and proton conduction was dominant below 350$^{\circ}C$. The activation energy for proton conduction was calculated as 0.72 eV.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.194-197
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• 2006

Lead-free bismuth-layered perovskite ferroelectric europium-substituted $Bi_{4}Ti_{3}O_{12}(BTO)$ thin films have been successfully deposited on Pt/Ti/$SiO_2$/Si substrate by a sol-gel spin-coating process. $Bi(TMHD)_3,\;Eu(THMD)_3,\;Ti(OiPr)_4$ were used as the precursors, which were dissolved in 2-methoxyethanol. The thin films were annealed at various temperatures from $600^{\circ}\;to\;720^{\circ}C$ in oxygen ambient for 1 hr, which was followed by post-annealed for 1 hr after depositing a Pt electrode to enhance the electrical properties. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the crystallinity and surface morphology of layered perovskite phase, respectively. The remanent polarization value of the BET thin films annealed at $720^{\circ}C\;was\;25.95{\mu}C/cm^2$ at an applied voltage of 5 V.

• Journal of Magnetics
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• v.2 no.4
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• pp.126-129
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• 1997

We have studied magnetostructural phase transitions in the perovskite-type layered structure compound (C18H37NH3)2 MnCl4 by means of electron paramagnetic resonance (EPR) and superconducting quantum interference device (SQUID) measurements. Distinct slopes were observed in the linear temperature dependences of the Mn++ EPR linewidth in the low and high temperature phases. Besides, linewidth anomalies at the transition temperatures sensitively reflect the magnetic changes arising from the MnCl6 octahedra.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.05a
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• pp.7.1-7.1
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• 2007

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.222-227
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• 2020

Pb(Zr,Ti)O₃(denoted as PZT) in the perovskite phase is used as a dielectric, piezoelectric, and super appetizer material owing to its ferroelectric properties. A PZT film was formed by an RF magnetron sputtering process by preparing a target composed of Pb_1.3(Zr_0.52Ti_0.48)O₃. The PZT film was formed by dividing the material into a mono-layer PZT produced continuously with the same sputtering power and a bi-layer PZT produced with two-stage sputtering power. The bi-layer PZT consisted of a lower layer produced under low-power sputtering conditions and an upper layer produced under the same conditions as the mono-layer PZT. XRD revealed small amounts of pyrochlore phase in the mono-layer PZT, but only the perovskite phase was detected in the bi-layer PZT. SEM and AFM revealed the upper part of the bi-layer PZT to be more compact and smooth. Moreover, the bi-layered PZT showed superior symmetry polarization and a significantly reduced leakage current of less than 1×10-5 A/cm². This phenomenon observed in bi-layer PZT was attributed to the induction of growth into a pure perovskite phase by suppressing the formation of a pyrochlore phase in the upper PZT layer where the densely formed lower PZT layer was produced sequentially.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.1
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• pp.14-19
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• 2013

We have successfully synthesized $Bi_{4-x}La_xTi_3O_{12}$ (x~2) having Aurivillius-type layered perovskite structure from exfoliated layered perovskite oxide of $K_2La_2Ti_3O_{10}$ with Ruddlesden-Popper structure. The reaction between the exfoliated lanthanum titanate nanosheets and BiOCl nanocrystal resulted in the formation of polycrystalline $Bi_{4-x}La_xTi_3O_{12}$ (x~2) after heating above $700^{\circ}C$. Colloidal suspension of the nanosheets could be obtained by intercalating ethylamine (EA) into the protonated lanthanum titanate, $H_2La_2Ti_3O_{10}$, derived from $K_2La_2Ti_3O_{10}$. Transmission electron microscopic (TEM) analysis show that the exfoliated lanthanium titanate nanosheets have a thickness of a few nano meters. According to X-ray diffraction (XRD) analysis, the exfoliated lanthanium titanate was found to be transformed into $Bi_{4-x}La_xTi_3O_{12}$ (x~2) after restacking with BiOCl and subsequent thermal treatment at > $700^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.233-239
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• 2000

Sr0.9Bi2+xTa2O9(x=0, 0.1, 0.2, 0.3) thin films on IrO2/SiO2/Si or Pt/Ti/SiO2/Si substrate were prepared by spin coating method using SBT stock solutions synthesized by MOD process. SBT thin films on IrO2 transformed to layered perovskite phase at $700^{\circ}C$, but showed low breakdown voltage due to their porous microstructure. The smaple of Sr0.9Bi2+xTa2O9 composition showed the best dielectric and electrical properties. When the sample of the same composition was annealed at 80$0^{\circ}C$, the dielectric and electric properties were improved due to the grian growth and dense surface. the remanent polarization values(2Pr) at $\pm$3 V for IrO2 and Pt electrodes were 10.5, 7.15$\mu$C/$\textrm{cm}^2$, respectively. The SBT thin film with IrO2 electrode showed the lower coercive field. The leakage current density and breakdown voltage of SBT thin films on IrO2 were higher than those on Pt.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.371-374
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• 2002

Bismuth lanthanum titanate thin films with excess Bi contents were prepared onto Pt/Ti/$SiO_2$/Si substrate by metalorganic decomposition (MOD) technique. The structure and morphology of the films were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. From the XRD analysis, BLT thin films show polycrystalline structure and the layered-perovskite phase was obtained over 10% excess of Bi contents. As a result of ferroelectric characteristics related to the Bi content of the BLT thin film, the remanent polarization and dielectric constant decreased with increasing over Bi content of 10 % excess. The BLT film with Bi content of 10% excess was measured to have a dielectric constant of n9 and dielectric loss of 1.85[%]. The BLT thin films showed little polarization fatigue test up to 3.5 x $10^{9}$ bipolar switching cycling.