• 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.

• 한국전기전자재료학회논문지
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• 제30권8호
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• pp.474-478
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• 2017

We report on thin-film transistors based on $TiO_x$ pre-annealed by femtosecond laser pulses. A 30-nm thick $TiO_x$ active channel layer was initially deposited by an ALD system. The $TiO_x$ semiconducting films were annealed by irradiation with a femtosecond laser (power: $3W/cm^2$) for 5, 25, and 50s. Atomic force microscopy images revealed that the surface of a $TiO_x$ film without femtosecond laser pre-annealing was relatively rough, while after annealing with femtosecond laser pulses, the surface of the $TiO_x$ films became smooth. With increasing radiation time, the surrounding gas atmosphere could have a larger impact on the $TiO_x$ surface; meanwhile, the thin-film roughness decreased. Thin-film transistors with $TiO_x$ active channels pre-annealed at 50s exhibited good transfer characteristics and an on-to-off current ratio of ${\sim}10^3$.

• 한국세라믹학회지
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• 제33권8호
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• pp.895-900
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• 1996

수산염볍으로 Ba(Ti1-xSnx)4O9 분말을 합성하였다. Ti자리에 Sn이 치환되면 생성된 BaTi4O9은 고용체를 형성하기 때문에 안정화되었다. BaTi4O9 결정상의 생성을 위한 최적 고용량은 0.16mole이었으며, 그 이상 첨가시는 BaTi4O9 결정 성장을 억제하였다. 0.16mole Sn을 첨가하여 135$0^{\circ}C$에서 30분 소결하였을 때 긴 막대형의 결정이 가장 잘 발달하였고, 이때 Q값이 가장 높았다. 그러나 Sn 첨가량이나 소결 유지시간을 변화시켜도 유전율은 거의 일정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.365-366
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• 2005

PZT films are the most intensively investigated because PZT has advantages such as low processing temperature and large remnant values. In this paper, the microstructure and electric properties of $Pb(Zr_x,Ti_{(1-x)})O_3/BaTiO_3$ heterolayered thick films with Zr mole ranging from 30 to 70 % screen printed onto a alumina substrate were studied. $Pb(Zr_x,Ti_{(1-x)})O_3$ and $BaTiO_3$ powders were prepared by the sol-gel method. The $BaTiO_3$ powders were calcined at $700^{\circ}C$ for 2 hours. Structural properties of $Pb(Zr_x,Ti_{(1-x)})O_3/BaTiO_3$ multilayered thick films were investigated. As a result of the X-ray diffraction (XRD) analysis, $Pb(Zr_x,Ti_{(1-x)})O_3/BaTiO_3$ exhibited a perovskite polycrystalline phase without pyrochlore phase or any preferred orientation.

• 한국세라믹학회지
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• 제34권8호
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• pp.843-853
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• 1997

The effect of dopant on microwave dielectric properties of (1-x)MgTiO3-xCaTiO3 ceramics, known to be used as microwave dielectric resonators for global positioning system and personal communication system, has been analyzed in terms of variations in defect concentrations and microstructural features with its addition. The addition of dopants was revealed to result in a significant change in the microstructure as well as defect concentration of the ceramics. For instance, the quality factor is proportional to sintered density of the ceramics by inversely proportional to grain size as well as vacancy concentration. Accordingly, it is believed that the dopant effect on the microwave dielectric properties should be separately analyzed with either microstructural change or the change in vacancy concentration.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.118-120
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• 2001

The $0.96MgTiO_3-0.04SrTiO_3+xLa(0{\sim}1.0wt%)$ ceramics were prepared by conventional mixed oxide method. The structural properties of $0.96MgTiO_3-0.04SrTiO_3+xLa(0{\sim}1.0wt%)$ ceramics with sintering temperature were investigated by the XRD and SEM. From the X-ray diffraction patterns, it was found that the perovskite $SrTiO_3$ and ilmenite $MgTiO_3$ structures were coexisted in the $0.96MgTiO_3-0.04SrTiO_3$ ceramics. The second phase of $Sr_{0.5}LaTi_2O_6$ was shown with addition of the $La_2O_3$. The dielectric constant(${\varepsilon}_r$), $Q{\times}f$ value and the temperature coefficient of the $0.96MgTiO_3-0.04SrTiO_3+0.2La$ ceramics were 21. 41, 39991, $-3.3ppm/^{\circ}C$, respectively.

• 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.

• 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.

• 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.

• 전자공학회논문지D
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• 제35D권10호
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• pp.51-59
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• 1998

(Na½Ln½) TiO₃(Ln = La, Pr, Nd, Sm)은 양의 온도계수(190 ∼ 480ppm/℃), 고유전율(99∼127)의 특성을 갖고 있다. 반면에 MgTiO₃는 음의 온도계수(-45ppm/℃), 저유전손실(110,000㎓)을 갖고 있다. 그래서 xMgTiO₃(1-x) (Na½Ln½) TiO₃의 유전특성에 관심을 갖게 되었고, 초고주파 대역에서의 유전특성을 측정하고 미세구조를 관찰하여, 몰비변화와 소결온도변화에 따른 경향성을 파악하였으며, 그 원인을 연구하였다. 그 결과 MgTiO₃와 (Na½Ln½) TiO₃는 구조적으로 새로운 고용체나 이차상을 형성하지 않는 혼합상을 이루고 있었다. 그리고 이들의 유전특성은 (Na½Ln½) TiO₃와 MgTiO₃의 중간 값을 나타냈고, logarithmic mixing rule로써 유전특성을 예측할 수 있다. 이중에서 온도에 안정한 조성은 Ln = La, Pr, Nd으로 치환되었을 경우 각각 x = 0.9, 0.87, 0.84이었다. 이때의 유전율은 22 ∼25, Qf값은 55000 ∼ 28000㎓를 나타내었다. 이로써 온도에 안정한 유전특성을 갖는 새로운 유전체 재료를 개발하였으며, 특히 Ln = La으로 치환되었을 경우 다른 조성에 비하여 유전특성이 좋을 뿐아니라, 소결온도 범위가 넓어 공정상의 잇점을 가지고 있다.