• 한국재료학회지
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• 제8권7호
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• pp.659-663
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• 1998

BaO.$Nd_{2}O_{3}$.$4TiO_{2}$세라믹스에서 Bi 치환위치 및 Bi 치환 량에 따른 상, 미세구조, 마이크로파 유전특성 등을 조사하였다. BaO.$Nd_{2}O_{3}$.$4TiO_{2}$ 세라믹스의 Nd 치환되어 $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$고용체 (0$\leq$x$\leq$0.2)를 형성하였다. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$에서 Bi 치환 량이 x=0에서 x=0.2까지 증가됨에 따라 입자크기가 계속 증가하였으며, 유전상수는 84에서 108까지 계속 증가하였고, 공진 주파수의 온도계수는 $44 ppm^{\circ}C$에서 $-30ppm^{\circ}C$로 계속 감소하였다. $BaO.(Nd_{1-x}Bi_x)_2O_3.4TiO_2$조성에서 Bi 치환 량이 x=0.04에서 0.08사이일 때 가장 양호한 마이크로파 유전특성이 얻어졌으며 이 때의 유전상수 (${\varepsilon}_r$)는 89~92, Q, f는 5855-6091 GHz, 그리고 공진 주파수의 온도계수 (${\tau}_f$)는 -7.7-7.5 ppm/$^{\circ}C$이었다.

• 한국결정성장학회지
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• 제23권1호
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• pp.14-19
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• 2013

본 연구팀에서는 층상형 페로브스카이트 구조를 갖는 Ruddlesden-Popper 구조의 $K_2La_2Ti_3O_{10}$의 박리화를 통해 Aurivillius 구조의 $Bi_{4-x}La_xTi_3O_{12}$(x~2) 페로브스카이트 산화물을 성공적으로 합성하였다. 박리화된 란타늄 티타네이트 나노시트는 BiOCl 나노결정구조와 반응시켜 $Bi_{4-x}La_xTi_3O_{12}$(x~2) 결정을 얻어내었다. 박리화된 나노시트 현탁액은 $K_2La_2Ti_3O_{10}$으로부터 수소화된 $H_2La_2Ti_3O_{10}$의 층간에 에틸아민을 삽입시킴으로써 얻어내었다. 투과전자현미경(TEM) 분석을 통해, 란타늄 티타네이트가 에틸아민에 의해 박리화된 것을 확인할 수 있었다. X-선 회절분석(XRD)을 통해, 박리화된 란타늄 티타네이트와 BiOCl의 재적층과정을 거쳐 $700^{\circ}C$ 이상의 열처리 조건에서 $Bi_{4-x}La_xTi_3O_{12}$(x~2)로 형성된 것을 확인할 수 있었다.

• 전자공학회논문지A
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• 제30A권5호
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• pp.30-35
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• 1993

We have investigated microwave dielectric properties of TiO$_{2}$ added (Pb$_{1-x}$Ca$_{x}$)ZrO$_{3}$ Ceramics with x=0.33, 0.35, and 0.37 sintered at 1400$^{\circ}C$ for 2 h. For additions of up to 3wt% of TiO$_{2}$ in (Pb$_{0.63}$ Ca$_{0.37}$)ZrO$_{3}$ (x=0.37), TiO$_{2}$ was completely soluble in (Pb, Ca)ZrO3 phase and did not affect the grain size of ceramics. Dielectric constant and temperature coefficient of resonant frequency increased due to the formation of solid solution, whereas Q value decreased linearly as TiO$_{2}$ increased up to 1 wt%. However, the dielectric loss was very high as TiO$_{2}$ exceeded 2 wt%. It was also shown that as Ca ion content in 0.5 wt% TiO$_{2}$ added (Pb$_{1-x}$,Ca$_{x}$)ZrO$_{3}$ decreased from x=0.37 to x=0.33, dielectric constant increased and Q value decreased.

• 한국환경과학회지
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• 제16권12호
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• pp.1431-1437
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• 2007

Cobalt titanates($CoTiO_x$), such as $CoTiO_3$ and $Co_2TiO_4$, have been synthesized via a solid-state reaction and characterized using X-ray diffraction(XRD) and X-ray photoelectron spectroscopic(XPS) measurement techniques, prior to being used for continuous wet trichloroethylene(TCE) oxidation at $36^{\circ}C$, to support our earlier chemical structure model for Co species in 5 wt% $CoO_x/TiO_2$(fresh) and(spent) catalysts. Each XRD pattern for the synthesized $CoTiO_3$ and $Co_2TiO_4$ was very close to those obtained from the respective standard XRD data files. The two $CoTiO_x$ samples gave Co 2p XPS spectra consisting of very strong main peaks for Co $2p_{3/2}$ and $2p_{1/2}$ with corresponding satellite structures at higher binding energies. The Co $2p_{3/2}$ main structure appeared at 781.3 eV for the $CoTiO_3$, and it was indicated at 781.1 eV with the $Co_2TiO_4$. Not only could these binding energy values be very similar to that exhibited for the 5 wt% $CoO_x/TiO_2$(fresh), but the spin-orbit splitting(${\Delta}E$) had also no noticeable difference between the cobalt titanates and a sample of the fresh catalyst. Neither of all the $CoTiO_x$ samples were active for the wet TCE oxidation, as expected, but a sample of pure $Co_3O_4$ had a good activity for this reaction. The earlier proposed model for the surface $CoO_x$ species existing with the fresh and spent catalysts is very consistent with the XPS characterization and activity measurements for the cobalt titanates.

• 공업화학
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• 제19권5호
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• pp.554-558
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• 2008

전구체로서 알콕사이드[Tetraethyl orthosilicate (TEOS), Titanium (IV) isopropoxide (TiP)]를 사용하여 졸-겔 방법으로 전기방사에 적합한 졸을 제조한 후, $(1-x)SiO_2-(x)TiO_2$계 복합 나노섬유를 제조하였다. 제조된 광활성 무기나노섬유의 표면 및 구조적 특성은 X-선회절분석(XRD), 주사전자현미경(SEM), 투과전자현미경(TEM), 열중량분석 및 미분주사칼로리미터분석 (TGA-DSC), 적외선분광분석((FT-IR)을 통하여 확인하였다. $(1-x)SiO_2-(x)TiO_2$계에서 $TiO_2$ 양이 증가하면 전기방사된 복합섬유직경은 증가하였으며, 저온에서 안정한 아나타제 $TiO_2$ 결정에서 루타일로의 상전이는 $1000^{\circ}C$에서의 열처리 후에도 고루 분산되어 있는 $SiO_2$로 인해 $0.6SiO_2-0.4TiO_2$계까지는 아나타제상으로 존재하였다. $SiO_2-TiO_2$계 복합체 나노섬유의 광활성은 메틸렌블루 광분해 실험 및 UV-vis/DRS 분석을 통해 자외선 영역에서 나타남을 확인하였다.

• 한국결정성장학회지
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• 제8권3호
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• pp.478-486
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• 1998

$CaCO_3,\;LaO_3,\;Nd_2O_3\;TiO_2의 혼합물을 1673K에서 소결하여 마이크로파 유전체 세라믹스재료로 응용이 가능한 (1-x)$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\letextrm x\le0.8)$계를 합성하였다. (1-x))$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\lex\le0.8)$계의 격자 정수는 x가 증가함에 따라 증가하였다. XRD의 Rietveld profile-analysis를 통하여 (1-x))$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\le \textrm {x} \le0.8)$계의 결정구조를 해석하였다. $0\le \textrm {x}\le0.8$의 모든 영역에서 양이온 $La^{3+},Nd^{3+}$는 $Ca^{2+}$ 자리에 점유하였다. x=0.6까지는 $CaTiO_3$와 같은 공간군 Pnma를 그대로 유지하였으며, x가 증가함에 $TiO_6$의 비틀림과 변형은 점차 감소하였다. x=0.8에서는 새로운 공간군 $Pmn2_1$으로 결정구조의 변화를 보였다. (1-x)$CaTiO_3-x(La_{1/3}Nd_{1/3}TiO_3\;(0\le \textrm {x}\le0.8)$계의 비유전율($\epsilon$r)은 x가 증가함에 따라 지수 함수적으로 감소하였다. 공진 주파수의 온도계수($\tau_f$)는 x=0.6까지 증가함에 따라 감소하였으나 x=0.8에서는 결정구조의 변화와 더불어 다시 증가하였다. Q.$\tau_f$값은 x=0.2에서는 13800(GHz)을 나타낸 후 0$0.4\le \textrm {x}\le0.8$ 영역에서는 2000 (GHz)의 매우 낮은 값을 나타내었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.97-97
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• 2003

Composition in the (Znl-xNix)2TiO4+ yTiO2 system (x=0-0.5, y=0-0.35) were synthesized via the solid-state reaction route. The incorporation of titanium, in the form of TiO2, in (Znl-xNix)2TiO4 spinel ceramics were investigated by analyzing the crystal structure and measuring the dielectric properties. The result of the crystal structure analysis suggested that TiO2 level of 0.01 y 0.33 could be incorporated into the (Znl-xNix)2TiO4 spinel. The change of incorporated TiO2 level is related with Co-content as a inverse proportion and the variation of lattice parameter and dielectric properties were supported the result.

• 한국표면공학회지
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• 제50권5호
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• pp.345-351
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• 2017

A double-layered anti-reflective coating with hydrophilic/abrasion-resistant properties was studied using anatase titanium dioxide($TiO_2$) and silicon oxycarbide($SiO_xC_y$) thin film. $TiO_2$ and $SiO_xC_y$ thin films were sequentially deposited on a glass substrate by DC sputtering and PECVD, respectively. The optical properties were measured by UV-Vis-NIR spectrophotometer. The abrasion-resistance and the hydrophilicity were observed by a taber abrasion tester and a contact angle analyzer, respectively. The $TiO_2/SiO_xC_y$ double-layer thin film had an average transmittance of 91.3%, which was improved by 10% in the visible light region (400 to 800 nm) than that of the $TiO_2$ single-layer thin film. The contact angle of $TiO_2/SiO_xC_y$ film was $6.9^{\circ}$ right after UV exposure. After 9 days from the exposure, the contact angle was $10.2^{\circ}$, which was $33^{\circ}$ lower than that of the $TiO_2$ single-layer film. By the abrasion test, $SiO_xC_y$ film showed a superior abrasion-resistance to the $TiO_2$ film. Consequently, the $TiO_2/SiO_xC_y$ double-layer film has achieved superior anti-reflection, hydrophilicity, and abrasion resistance over the $TiO_2$ or $SiO_xC_y$ single-layer film.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1257-1261
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• 1994

Phsysical and dielectric properties of $(1-x)CaTiO_3-xLa(Zn_{1/2}Ti_{1/2})O_3$ ceramics were investigated at the temperature range of $25^{\circ}C$ to $80^{\circ}C$ at the frequency of 6 GHz. As increasing addition of the amount of $La(Zn_{1/2}Ti_{1/2})O_3$ to x = 5 mol,Q value was increased due to grain growth and increase of density. For more addition, Q value decreased due to electrical defect. Temperature coefficient of resonant frequency could be controlled by the amount of $La(Zn_{1/2}Ti_{1/2})O_3$, which could be explained by volume mixing rule.

• 한국세라믹학회지
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• 제34권9호
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• pp.921-926
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• 1997

Two NbCx-C1-x/Y2O3/Ti sputter-coated Al2O3 substrates (L 5.5 cm$\times$W 0.5 cm) were diffusion bonded together using hot press method at 95$0^{\circ}C$ for 3 hours under 1 MPa of applied pressure. 4 points bending tests were used to evaluate the mechanical performance of these precracked laminate beams. Two types of mechanical responses were observed: crack penetration through the interface for x=0.75, 1 and crack deflection into an interface for x=0.25, 0.5. The Al2O3/NbCx-C1-x/Y2O3/Ti system suggested here has been proves to be effective for the thermokinetical stability and tailorability of the interfaces of Al2O3/Ti composites at 95$0^{\circ}C$.