• 한국전기전자재료학회논문지
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• 제16권5호
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• pp.361-364
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• 2003

It was investigated that the structural and electrical Properties of Ce-doped Ba(Zr$_{x}$Ti$_{1-x}$ )O$_3$ (BCZT) thin films with a mole fraction of x=0.2 and a thickness about 100 nm. BCZT films were prepared on Pt/Ti/SiO$_2$/Si substrate by a RF magnetron sputtering system. We have measured the thickness profile with Ar/O$_2$ ratio and the surface roughness. It was observed that the oxygen gas, which introduced during the film deposition, have an influence on the roughness of the film and the film roughness was reduced by annealing from 2.33 nm to 2.02 nm (RMS at 500 $^{\circ}C$, Ar:6 sccm, $O_2$:6 sccm). It was found that annealing procedure after top electrode deposit can reduce the dissipation factor.

• 대한전기학회논문지
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• 제41권8호
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• pp.858-868
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• 1992

0.085Ba(LaS11/2TNbS11/2T)OS13T-0.915Pb(ZrS1yTTiS11-yT)OS13T (0.45$\leq$y$\leq$0.65) transparent electrooptic ceramics were fabricated by two-stage sintering method. The structural, ferroelectric and electrooptic properties were investigated varying composition and second sintering time. Also the possibility of application to electrooptic device was studied. If we increase the PbZrOS13T contents, dielectric constants were increased and Curie temperature was decreased. In the composition of 0.55[mol] PbZrOS13T, electromechanical coupling factor and piezoelectric charge constant were the highest values of 43[%] and 173x10S0-12T[C/N], respectively. Mechanical quality factors were decreased with the increasing PbZrOS13T contents. Light transmittance was increased with wavelength when measured from 300[nm] to 900[nm], and with PbZrOS13T contents in the range of 0.50[mol]-0.65[mol], and had the highest value of 67[%] in the composition of 0.65[mol] PbZrOS13T. From the results of ferroelectric hysteresis loop and transmitted light intensity with electric field, the specimens with compositions of 0.65,0.60,0.55[mol] PbZrOS13T were applicable to electrooptic memory device and those with compositions of 0.50,0.45[mol] PbZrOS13T were applicable to linear electrooptic device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.302-302
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• 2007

The $SrRuO_3$/Si thin film electrodes are grown with (00l) preferred orientations on SrO buffered-Si (001) substrates by pulsed laser deposition. The optimum conditions of SrO buffer layers for $SrRuO_3$ preferred orientations are the deposition temperature of $700^{\circ}C$, deposition pressure of $1\;{\times}\;10^{-6}\;Torr$, and the thickness of 6 nm. The 100nm thick-$SrRuO_3$ bottom electrodes deposited above $650^{\circ}C$ on SrO buffered-Si (001) substrates have a rms roughness of approximately $5.0\;{\AA}$ and a resistivity of 1700 -cm, exhibiting a (00l) relationship. The 100nm thick-$Pb(Zr_{0.2}Ti_{0.8})O_3$ thin films deposited at $575^{\circ}C$ have a (00l) preferred orientation and exhibit $2P_r$ of $40\;C/cm^2$, $E_c$ of 100 kV/cm, and leakage current of about $1\;{\times}\;10^{-7}\;A/cm^2$ at 1V.

• 한국재료학회지
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• 제8권3호
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• pp.256-262
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• 1998

산소이온전도체 13mol% CaO안정화 $ZrO_{2}$에 대한 $AI_{2}$$O_{3}$의 첨가효과를 살펴보기 위해 출발원료분말을 ($Zr_{0.87}$ $Ca_{0.13}$ O$1.87_{1-x}$ $AI_{2}$$O_{3}$)x,(x=0,0.01,0.02,0.03,0.05)와 같은 조성이 되도록 공침법으로 합성하고 $1400^{\circ}C$에서 소결시켜, $AI_{2}$$O_{3}$의 첨가에 따른 /grain size의 변화, $AI_{2}$$O_{3}$의 형태 및 존재위치, 소결밀도의 변화, 그리고 저항률의 변화를 살펴보았다. 그 결과, 결정립의 크기는 1mol% A $I_{2}$$O_{3}$첨가까지는 증가하였고, 2mol%첨가이상에서는 입계로 석출하기 시작한 $AI_{2}$$O_{3}$의 pinning효과에 기인되어 감소하였다. 또 1mol% $AI_{2}$$O_{3}$첨가시에 격자상수값의 급격한 감소가 보여지고, 그 이상에서는 변화가 별로 없어 13mol%CaO안정화 $ZnO_{2}$의 고용도한은 최대 1mol%임을 알 수 있었다. 전기전도도 또한 1mol% $AI_{2}$$O_{3}$첨가시에 증가됨을 나타냈다. $ZrO_{2}$에의 고용도한까지의 $AI_{2}$$O_{3}$첨가는 결정립성장을 촉진시키며 밀도값의 증대를 가져오고 전기전도도의 증가를 가져오는 긍정적인 효과를 나타냈다.

• 한국분말재료학회지
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• 제8권3호
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• pp.163-167
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• 2001

A bulk porous $CaZrO_3/MgO$ composite with plantinum nano-dispersion was synthesized in air atmosphere through the combination of several in situ reactions, including the pyrolysis of $PtO_2$. A mixture of $CaMg(CO_3)_2$(dolomite), $ZrO_2$, $PtO_2$ and LiF (0.5 wt%, as an additive) was cold isostatically pressed at 200 MPa and sintered at $1100^{\circ}C$ for 2 h. The porous $CaZrO_3/MgO/Pt$ composite ($CaZrO_3/MgO$ : Pt=99 : 1 in volume) had a uniformly open-porous structure (porosity: 56%) with three-dimensional (3-D) network and a narrow pore-size distribution, similarly to the porous $CaZrO_3/MgO$ composites reported before. Catalytic Properties (viz., NO direct decomposition and NO reduction by $C_2H_4$) of the $CaZrO_3/MgO/Pt$ composite were investigated up to $900^{\circ}C$. In the absence of oxygen, the NO conversion rate reached ~52% for the direct decomposition and ~100% for the reduction by $C_2H_4$, respectively. The results suggest the possibility of the porous composite as a multifunctional filter, i.e., simultaneous hot gas-filtering and $de-NO_x$ in one component.

• 전기학회논문지
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• 제57권11호
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• pp.2015-2022
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• 2008

The effect of content of $Al_2O_3+Y_2O_3$ sintering additives on the densification behavior, mechanical and electrical properties of the pressureless-sintered $SiC-ZrB_2$ electroconductive ceramic composites was investigated. The $SiC-ZrB_2$ electroconductive ceramic composites were pressurless-sintered for 2 hours at 1,700[$^{\circ}C$] temperatures with an addition of $Al_2O_3+Y_2O_3$(6 : 4 mixture of $Al_2O_3$ and $Y_2O_3$) as a sintering aid in the range of $8\;{\sim}\;20$[wt%]. Phase analysis of $SiC-ZrB_2$ composites by XRD revealed mostly of $\alpha$-SiC(6H), $ZrB_2$ and In Situ YAG($Al_5Y_3O_{12}$). The relative density, flexural strength, Young's modulus and vicker's hardness showed the highest value of 89.02[%], 81.58[MPa], 31.44[GPa] and 1.34[GPa] for $SiC-ZrB_2$ composites added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at room temperature respectively. Abnormal grain growth takes place during phase transformation from $\beta$-SiC into $\alpha$-SiC was correlated with In Situ YAG phase by reaction between $Al_2O_3$ and $Y_2O_3$ additive during sintering. The electrical resistivity showed the lowest value of $3.l4{\times}10^{-2}{\Omega}{\cdot}cm$ for $SiC-ZrB_2$ composite added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at 700[$^{\circ}C$]. The electrical resistivity of the $SiC-TiB_2$ and $SiC-ZrB_2$ composite was all negative temperature coefficient resistance (NTCR) in the temperature ranges from room temperature to 700[$^{\circ}C$]. Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites.

• Transactions on Electrical and Electronic Materials
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• 제16권3호
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• pp.130-134
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• 2015

This research proposes the use of a composition modulated (ZrO₂)_x(Al₂O₃)_1-x film as a charge trapping layer for charge trap flash memory; this is possible when the Zr (Al) atomic percent is controlled to form a variable bandgap as identified by the valence band offsets and electron energy loss spectrum measurements. Compared to memory devices with uniform compositional (ZrO₂)_0.1(Al₂O₃)_0.9 or a (ZrO₂)_0.92(Al₂O₃)_0.08 trapping layer, the memory device using the composition modulated (ZrO₂)_x(Al₂O₃)_1-x as the charge trapping layer exhibits a larger memory window (6.0 V) at the gate sweeping voltage of ±8 V, improved data retention, and significantly faster program/erase speed. Improvements of the memory characteristics are attributed to the special energy band alignments resulting from non-uniform distribution of elemental composition. These results indicate that the composition modulated (ZrO₂)_x(Al₂O₃)_1-x film is a promising candidate for future nonvolatile memory device applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.181-184
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• 1993

Microwave characteristics of the system (Zr, Sn)$TiO_4$, ceramics within composition range X between 0.2 and 0.35 were investigated at 8GHz. For the improvement properties of (Zr, Sn)$TiO_4$, system, $Ta_2O_5$ and $WO_3$ addition in the range of 0.5 to 2.0wt% were investigated.

• 한국세라믹학회지
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• 제41권1호
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• pp.1-8
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• 2004

The microstructural features and mechanical behavior of directionally solidified $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fibers after extended beat treatment in oxidizing environment were investigated. The fiber was grown continuously by an Edge-defined Film-fed Growth (EFG) technique. The microstructure was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy(SEM). The microstructure of the fiber in the as-fabricated state consists of highly oriented colonv and fine lamellar microstructure along the fiber axis. Tensile strength of the $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber remained unchanged with heat treatment at temperatures between $1200^{\circ}C$ and $1500^{\circ}C$ up to 300h. The weibulls modulus remained fairly constant after extended thermal exposure. The fracture toughness and crack propagation behavior were investigated. The fracture toughness ($K_{1C}$) of the $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber in the as-fabricated state were measured to be 3.6 ${\pm}$ 0.5 MPa${\cdot}m^{1/2}$ by an indentation technique and 2.2 ${\pm}$ 0.2 MPa${\cdot}m^{1/2}$ by assuming elliptical flaw of a semi-infinite solid, respectively. The $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber showed a radial (Palmqvist) crack type and exhibited an orthotropic crack growth behavior under 100 g load.

• 한국세라믹학회지
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• 제37권4호
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• pp.354-358
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• 2000

Tetragonal (t)-ZrO2/Al2O3 composites doped with Y2O3, Nb2O5, and Fe2O3 ((Y, Nb, Fe)-TZP/Al2O3) were prepared over the range containing Fe2O3 from 0.1 to 0.5 mol% with 0.1 mol% intervals to evaluate the effect of Fe2O3 addition on chromaticity, hydrothermal stability, and mechanical property of the composites. After autoclaving for 20 h at 18$0^{\circ}C$ under 3.5 MPa water vapor pressure, no tlongrightarrowm phase transformation was observed probably due to the preferential solid solubility of Fe2O3 in Al2O3, the presence of the rigid Al2O3 particles, and the inherent phase stability of (Y, Nb)-TZP. The optimized strength and the fracture toughness of the composite were 700 MPa and 8.5 MPa.m1/2, respectively, when 0.1 mol% Fe2O3 was added. The composites have shown a gradual color change from a slightly white ivory to a pale yellowish brown with increasing the Fe2O3 concentration.