• Title/Summary/Keyword: $TiO_2$

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Low Temperature Preparation and Photocatalytic Activity of TiO{2-x}Nx (TiO{2-x}Nx의 저온제조 및 광화학적 특성)

  • Jung, Dong-Woon
    • Journal of the Korean Chemical Society
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    • v.54 no.1
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    • pp.120-124
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    • 2010
  • $TiO_2$ and N-substituted $TiO_{2-x}N_x$ were synthesized by using precipitation method. $TiO_{2-x}N_x$ compound absorbed whole UV light as well as long wavelength of visible light (400 - 700 nm) because of the change of band gap from 3.2 eV to 1.77 eV. Results obtained revealed that $TiO_{2-x}N_x$ showed higher activity than pure $TiO_2$ or P-25 for visible-photocatalytic degradation of 1,4-dichlorobenzene.

Photocatalayst and Decomposition Properties of TiO2 and TiO2-CdS Powders Prepared by Supercritical Fluid Method (초임계 유체법으로 제조한 TiO2 및 TiO2-CdS계 광촉매의 분해물성 연구)

  • 전일수;황수현;박상준;길현식;조승범;전명석;임대영
    • Journal of the Korean Ceramic Society
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    • v.41 no.6
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    • pp.481-484
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    • 2004
  • TiO$_2$ and TiO$_2$-CdS powders which were expected to be highly activated photocatalysts were prepared using supercritical fluid method (SCF). The prepared photocatalyst TiO$_2$ powders were crystalline of anatase and ultrafine spherical powders with large specific surface area. When photodecompositoion reaction was done with TiO$_2$ powders prepared by SCF as a photocatalyst in DCA (Dichloroactic Acid) solution, a hazardous organic compound, the photocatlyst, properties of TiO$_2$ powders prepared by SCF were better than that of commercial TiO$_2$ powders.

Investigation on the Preparation Method of TiO2-mayenite for NOx Removal (질소산화물 제거를 위한 TiO2-mayenite 제조 방법에 관한 연구)

  • Park, Ji Hye;Park, Jung Jun;Park, Hee Ju;Yi, Kwang Bok
    • Clean Technology
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    • v.26 no.4
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    • pp.304-310
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    • 2020
  • In order to apply a photocatalyst (TiO2) to various building materials, TiO2-mayenite was prepared in this study. The TiO2 was synthesized using the sol-gel method by fixing titanium isopropoxide (TTIP) and urea at a ratio of 1 : 1. Later, they were calcined in a temperature range of 400-700 ℃ to analyze the properties according to temperature. BET, TGA, and XRD were used to analyze the physical and chemical properties of TiO2. The nitrogen oxide removal test was confirmed by measuring the change in the concentration of NO for 1 h according to KS L ISO 22197-1. The prepared TiO2 samples exhibited an anatase crystal structure below 600 ℃, and TiO2 (urea)-400 showed the highest nitrogen oxide removal rate at 2.35 µmol h-1. TiO2-mayenite was prepared using two methods: spraying TiO2 dispersion solution (s/s) and sol-gel solution (g/s). Through BET and XRD analysis, it was found that 5-TiO2 (g/s) prepared by spraying a sol-gel solution has maintained its crystallinity even after heat treatment. Also, 5-TiO2 (g/s)-500 showed the highest removal rate of 0.55 µmol h-1 in the nitrogen oxide removal test. To prepare TiO2-mayenite, it was confirmed that mayenite should be blended with TiO2 in a sol-gel state to maintain the crystal structure and exhibit a high nitrogen oxide removal rate.

Behaviors of Abnormal Expansion in $Ba_2Ti_9O_{20}$ Ceramics during Calcination Process ($Ba_2Ti_9O_{20}$ 요업체의 하소공정중 이상팽창 거동)

  • 성제홍;김정주;김남경;조상희
    • Journal of the Korean Ceramic Society
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    • v.36 no.12
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    • pp.1327-1334
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    • 1999
  • Behaviors of abnormal expansion during calcination process of Ba2Ti9O20 ceramics and its related effects on the sintering characteristics were investigated as a function of precursors. When BaCO3 and TiO2 powders were used as starting materials. BaTi4O9 phase which has relatively large molar volume was formed drastically with abnormal ex-pansion during the calcination at 95$0^{\circ}C$ to 115$0^{\circ}C$ ON the contrary using BaTiO3 and TiO2 powders as starting materials led to retardation of the formation of BaTi4O9 phase and concurrently suppressed the abnormal expansion during cal-cination process. Especially the calcined powder of BaTiO3 and TiO2 had advantages in the densification and formation of Ba2Ti9O20 single phase in the sintering process.

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Photoelectrical Conductivity and Photodegradation Properties of $TiO_2$ and Ag Sputtered $TiO_2$ Plasma Spraying Coatings ($TiO_2$ 및 Ag 스퍼터링-$TiO_2$ 플라즈마 용사피막의 광전류 및 광분해 특성)

  • Kang, Tae-Gu;Jang, Yong-Ho;Park, Kyeung-Chae
    • Journal of Welding and Joining
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    • v.27 no.2
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    • pp.38-43
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    • 2009
  • In this study, we investigated photocatalytic ability of plasma sprayed $TiO_2$ and Ag sputtering $TiO_2$(Ag-$TiO_2$) coatings. A sputtering processes were adopted to coat the surface of $TiO_2$ with Ag(99.99%). Ag was sputtered at 10mA, 450V for $1{\sim}11$ seconds. $TiO_2$ and Ag-$TiO_2$ coatings were heat-treated at 250, 300, 350, $400^{\circ}C$ for $0{\sim}240$seconds. Photoelectrical conductivity was measured by four-point probe, and photodegradation was calculated by UV-V is spectrometer. Microstructure observation of $TiO_2$ and Ag-$TiO_2$ coatings were investigated by SEM. Crystal structure of $TiO_2$ and Ag-$TiO_2$ coatings were investigated by XRD. Qualitative analyses of $TiO_2$ and Ag-$TiO_2$ coatings were conducted by EDX. When $TiO_2$ coatings were heat-treated at $350^{\circ}C$ for 30 sec, photoelectrical conductivity and photodegradation were best. And in XRD analysis result, (101)/(110) relative intensity ratio of $TiO_2$(rutile) was comparably changed with photoelectrical conductivity. When Ag-$TiO_2$ coatings were heat-treated at $350^{\circ}C$ for 30 [sec] after sputtering Ag for 7 sec, Photoelectrical conductivity and photodegradation are best. Surface of coatings in such condition has very small and uniform Ag particles.

Crystal Structure of $TiO_2-SnO_2$ Fine Powders Prepared by Coprecipitation (공침법에 의해 제조된 $TiO_2-SnO_2$ 미분말의 결정구조)

  • 이종흔;박순자
    • Journal of the Korean Ceramic Society
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    • v.30 no.9
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    • pp.740-746
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    • 1993
  • TiO2-SnO2 fine powders prepared by coprecipitation from TiCl4-SnCl4 aqueous solution, and their crystal structures were studied. All the TiO2-SnO2 fine powders calcined at 180~$700^{\circ}C$ showed the complete solid solution between TiO2(rutile structure) and SnO2(rutile structure). This crystal structure of TiO2-SnO2 powders is thought to be originated mainly from the heterogeneous nucleation of Ti-hydroxde on the Sn-hydroxide with coherent structure.

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Aging Effect on the Antimicrobial Activity of Nanometal (Au, Ag)-Titanium Dioxide Nanocomposites (Aging 효과에 따른 나노메탈(Au, Ag)-이산화티탄 복합체의 항균 활성도)

  • Park, Hye-Rim;Lee, Sang-Wha;Yoo, In-Sang
    • Applied Chemistry for Engineering
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    • v.23 no.3
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    • pp.293-296
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    • 2012
  • Nanocomposites were fabricated as titanium dioxide ($TiO_2$) doped with nanometals (Au, Ag) by sonochemical reduction method and sol-gel method in order to investigate their antimicrobial activities. Then, the antimicrobial activity of the resulting samples was compared by the measurement of colony numbers survived on the agar plate incubated for 24 h after the loading E. coli on the solid-state media with the nanocomposites. The initial antimicrobial activity of the metal (Au, Ag)-doped $TiO_2$ was higher than that of the pristine $TiO_2$. Afterwards the nanocomposite samples were kept at $4^{\circ}C$ for a long time and the aged samples exhibited the different antimicrobial activity. With the elapse of aging times, Ag-doped $TiO_2$ with $TiO_2$ coating ($Ag-TiO_2$@$TiO_x$) exhibited the higher antimicrobial activity than those of $Ag-TiO_2$and $Au-TiO_2$. The $TiO_2$ coating on the $Ag-TiO_2$ may prevent the oxidation of Ag nanometals and stabilize colloidal nanocomposites.

Chemical Binding States of Ti and O Elements in Anodic Ti Oxide Films (Ti 양극산화 피막에서 Ti 및 O원소의 화학결합 상태)

  • 유창우;오한준;이종호;장재명;지충수
    • Journal of the Korean institute of surface engineering
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    • v.35 no.6
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    • pp.383-390
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    • 2002
  • To investigate behaviors of Ti and O elements and microstructures of anodic titanium oxide films, the films were prepared by anodizing pure titanium in $H_2$S $O_4$, $H_3$P $O_4$, and $H_2O$$_2$ mixed solution at 180V. The microstructures and chemical states of the elements were analyzed using SEM, X-ray mapping, AFM, XRD, XPS (depth profile). The films formed on a titanium substrate showed porous layers which were composed of pore and wall, And with increasing anodizing time a hexagonal shape of cell structures were dominant and solace roughness increased. From the XRD result the structure of the Ti $O_2$ layer was anatase type of crystal on the whole. In the XPS spectra it was found that Ti and O were chemically binded in forms of Ti $O_2$, TiOH, $Ti_2$ $O_3$ at Ti 2p, and Ti $O_2$, $Ti_2$ $O_3$, $P_2$ $O_{5}$, S $O_4^{2-}$ at O ls respectively. Concentration of Ti $O_2$ decreased as the depth increased from the surface of the oxide film towards the substrate, but to the contrary concentrations of TiOH and $Ti_2$ $O_3$ increased.d.

Optical Properties of $TiO_2/M/Ag/M/TiO_2$ Films with Different Diffusion Barrier Layers (확산방지막에 따른 $TiO_2/M/Ag/M/TiO_2$ 투명 열절연 박막의 광학적 성질)

  • 이경준;이진구;박주동;김진현;김영환;오태성
    • Journal of the Korean Vacuum Society
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    • v.5 no.2
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    • pp.147-155
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    • 1996
  • Optical properties of $TiO_2/M/Ag/M/TiO_2$ films have been changed with the diffusion barrier metal M. Optimum opticla properties of $TiO_2/M/Ag/M/TiO_2$ as the transparent heat mirror film, could be obtained with Ti among diffusion barrier metals of Ti, Cu, Zr and Al. $TiO_2/M/Ag/M/TiO_2$ film, which was fabricated by sputtering of 18 nm-thick $TiO_2$ and Ag, and 4nm-thick Ti, showed maximum transimittance of 89% at visible wavelength and infrared reflectance of 97% at wavelength of 3000 nm. Optical properties of this film was not degraded by Xenon-sunshine weather test for 240 hours. For specimens with barrier layers of Cu, Zr, and Al, degradation of optical properties by weather test was increased in a sequence of films with Cu, Zr, and Al barrier layers.

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Preparation of $BaTiO_3$ powder in solid reaction and basic study on dielectrics of $CeAIO_3-BaTiO_3$system ($BaTiO_3$ 분말합성조건 및 $CeAIO_3-BaTiO_3$계 유전체의 기초적 연구)

  • Lim, Dae-Young;Kim, Jong-Ock;Lee, Chae-hyun;Park, Won-Kyu
    • The Journal of Natural Sciences
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    • v.8 no.1
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    • pp.61-69
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    • 1995
  • It is hard to synthesize pure $BaTiO_3$ from $BaCO_3$ and $TiO_2$ in solid reaction for the activity of BaO and secondary phase. For this reason, the wet chemical techniques have been studied. Starting material which was used in these methods were expensive and the properties of powder which was synthesized in same defined. So, some process have been studying again to improve soild reaction method. This study which was one of those was to defin the forming mechanism of $Ba_2TiO_4$ and to control some condition of $Ba_2TiO_4$. The synthesis temperature of $BaTiO_3$ in solid reaction was near $1120^{\circ}C$. The quantity and forming temperature of $Ba_2TiO_4$ could be controlled by atmosphere heat treatment. $Ba_2TiO_4$ was related to expansion in Ba-rich region of $BaTiO_3$. $BaTiO_2O_5$ and $BaTiO_3O_7$ was reason to expand in Ti-rich region. The dielectrics of $CeAIO_3$ which was synthesized and sintered in reduction atmosphere and $BaTiO_3$ system were affected by $CeO_2$ which was formed for the decomposition of $CeAIO_3$ heat treatment in air.

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