• Title/Summary/Keyword: Silica thin film

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Ambient Pressure Dried Silica Aerogel Thin Film from Water Glass

  • Cha, Young-Chul;Yoon, Jong-Seol;Lee, Jun;Hwang, Hae-Jin;Moon, Ji-Woong
    • Journal of the Korean Ceramic Society
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    • v.45 no.2
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    • pp.87-89
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    • 2008
  • A nano structured silica aerogel thin film was manufactured from inexpensive sodium silicate (water glass) using an ambient pressure drying method. High purity silicic sol was prepared by passing a water glass solution through an ion exchange resin, and the gel films were prepared on a modified glass substrate via dip coating. The dip coating conditions, such as coating time and solvent, were optimized. The optical and physical properties of the obtained silica aerogel thin film were characterized using a UV-visable spectrometer and a scanning electron microscope.

Influence of $TiO_2$ Thin Film Thickness and Humidity on Toluene Adsorption and Desorption Behavior of Nanoporous $TiO_2/SiO_2$ Prepared by Atomic Layer Deposition (ALD)

  • Sim, Chae-Won;Seo, Hyun-Ook;Kim, Kwang-Dae;Park, Eun-Ji;Kim, Young-Dok;Lim, Dong-Chan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.268-268
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    • 2012
  • Adsorption and desorption of toluene from bare and $TiO_2$-coated silica with a mean pore size of 15 nm was studied using breakthrough curves and temperature programmed desorption. Thicknesses of $TiO_2$ films prepared by atomic layer deposition on silica were < 2 nm, and ~ 5 nm, respectively. For toluene adsorption, both dry and humid conditions were used. $TiO_2$-thin film significantly improved toluene adsorption capacity of silica under dry condition, whereas desorption of toluene from the surface as a consequence of displacement by water vapor was more pronounced for $TiO_2$-coated samples with respect to the result of bare ones. In the TPD experiments, silica with a thinner $TiO_2$ film (thickness < 2 nm) showed the highest reactivity for toluene oxidation to $CO_2$ in the absence and presence of water. We show that the toluene adsorption and oxidation reactivity of silica can be controlled by varying thickness of $TiO_2$ thin films.

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Characteristics Evaluation of Thin Films Formed on Mg-Al Alloy in Various Chemical Conversion Solution Conditions (다양한 화성처리 용액 조건에서 마그네슘-알루미늄 합금위에 형성된 박막의 특성 평가)

  • Jang Seok-Ki;Kim Seong-Jong;Kim Jeong-Il
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.1
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    • pp.98-106
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    • 2005
  • The chemical conversion film formed on magnesium alloy was investigated by using the colloidal silica with some parameters such as solution pH. temperature, solution conditions, and treatment time. Moreover. the solutions consisted of colloidal silica titanium sulfate, and cobalt ions were used for the colloidal silica film to having a good corrosion resistance and adhesion properties. It was thought that the film at 298K was made with combination of Si-O. The quantity of film formed at high temperature such as 333K and 353K is smaller than dissolved quantity during chemical conversion treatment. Adding $CoSO_4$ to the colloidal silica solution enhanced the adhesion force between the silica film and magnesium substrate, The optimum conditions for the chemical conversion treatment solution were PH 2.90 s treatment, and 298K.

Electrical Instabilities of Mesoporous Silica Thin Films

  • Dung, Mai Xuan;Jeong, Hyun-Dam
    • Journal of Integrative Natural Science
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    • v.3 no.4
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    • pp.219-225
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    • 2010
  • On the surface of mesoporous silica thin films (MSTF) which were fabricated by sol-gel approach there are existences of water and three different silanol types including chained, germinal and isolated silanol. Their amounts changes as a function of aging time of used sol solution, as confirmed by FT-IR. The adsorbed water generates ionic carriers such as H+ and OH- and passivates the Si dangling bonds at the interface of silicon wafer-MSTF. The ionic carriers can not only transport across the thickness of thin film to enhance the leakage current but also diffuse toward the silicon wafer-MSTF interface to depassivate Si dangling bonds. On the other hand, chained silanols or germinal silanols promote the moisture adsorption of MSTF and tend to form strongly hydrogen bonded systems with adsorbed water molecules resulting in very high dielectric constant. Isolated silanol, on the contrary, affects less on electrical properties of thin film.

Effect of surface modifiers on the nano porous silica aerogels prepared by ambient drying process (상압건조 나노다공성 실리카 에어로젤에 대한 개질제 효과)

  • Kim, Tae-Jung;Oh, Young-Jei
    • Journal of Sensor Science and Technology
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    • v.16 no.1
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    • pp.77-83
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    • 2007
  • Nanoporous silica aerogels with various surface modifiers were prepared by ambient drying process. Tetraethylorthosilicate (TEOS) were used a raw material. Ambient drying process for various surface modifier was studied in the point of view of a crack-free monolith and thin films and low cost. Various kinds of surface modifiers like as hexamethyldisilazane (HMDSZ), trimethlychlorosilane (TMCS), methlytriethoxylsilane (MTES), and methlytrimethoxysilane (MTMS) were studied in order to enhance hydrophobicity for the silica aerogel. Surface modified aerogels were evaluated by FT-IR, TG, BET, SEM and wetting angle measurement. Homogeneous and crack-free aerogels were obtained by modifying the HMDSZ and the TMCS. However silica xerogel was obtained when modified with MTMS, MTES.

Titanium thin film modified silica substrate to enhance the bonding properties of nanosilver

  • Lin, H.M.;Liu, Y.T.;Lin, K.N.;Chang, W.S.;Wu, C.Y.;Liu, P.Y.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1733-1736
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    • 2006
  • Nanosilver has intrinsic problem to adhesion on the surface of silica. To improve interfacial properties between nanosilver and silica substrate, a thin titanium film is introduced in this study. The titaniumcoated silica substrates are prepared by sputter technique. The commercial silver nanopaste with size around 3-7nm is used in this study. The results indicate thin layer of titanium can improve the bonding properties of nanosilver and expect to be used in fabrication of TFT display panel.

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Refractive Index Dispersion of Sputter-Deposited Silicon-Rich Silica Thin Films (스퍼터링 방법으로 증착된 실리콘 과잉 실리카 박막의 굴절률 분산)

  • Jin, Byeong-Kyou;Choi, Yong-Gyu
    • Journal of the Korean Ceramic Society
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    • v.46 no.1
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    • pp.10-15
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    • 2009
  • We have fabricated silicon-rich silica thin films via RF magnetron sputtering using a SiO target. Thickness evolution and microstructure change of such $SiO_x$ (1$SiO_x$ thin films turned out to be mainly responsible for the increase of refractive index.

Preparation of Silicon Oxide Thin Film using Hydrofluorosilicic Acid (규불화수소산을 이용한 실리콘 산화물 필름 제조에 관한 연구)

  • Park, Eun-Hui;Jeong, Heung-Ho;Im, Heon-Seong;Hong, Seong-Su;No, Jae-Seong
    • Korean Journal of Materials Research
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    • v.9 no.4
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    • pp.414-418
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    • 1999
  • Typical metal oxide thin films having optical and electrical properties are widely used as inorganic functional materials. Liquid phase deposition(LPD) method, a new low temperature process, has been developed for the several advantages of no vacuum system, low cost, high throughput, and low processing temperature(<$50^{\circ}C$). Silica powder was added to 40wt% hydrofluoro-silicic acid($H_2$SiF\ulcorner) to obtain an immersing solution of silica-saturated hydrofluorosilicic acid solution. Boric acid solution was continuously added in the range from 0 to 0.05M to prepare supersaturated hydrofluorosilicic acid solution. LPD $SiL_2$film was formed with the variation of added amount of $H_2$O. The SiO$_2$thin film could be prepared from hydrofluorosilicic acid by LPD method. The thickness of LPD $_SiO2$film was influenced by the boric acid concentration and added amount of $H_2$O. Silicon in thin film existed as SiF\ulcorner by Raman spectrum.

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Formation of Silver Nanoparticles on Silica by Solid-State Dewetting of Deposited Film (증착 박막의 비젖음에 의한 실리카 표면 위 은나노 입자형성)

  • Kim, Jung-Hwan;Choi, Chul-Min;Hwang, So-Ri;Kim, Jae-Ho;Oh, Yong-Jun
    • Korean Journal of Metals and Materials
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    • v.48 no.9
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    • pp.856-860
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    • 2010
  • Silver nanoparticles were formed on silica substrates through thin film dewetting at high temperature. The microstructural and morphological evolution of the particles were characterized as a function of processing variables such as initial film thickness, annealing time, and temperature. Silver thin films were deposited onto the silica using a pulsed laser deposition system and annealed in reducing atmosphere to induce agglomeration of the films. The film thicknesses before dewetting were in the range of 5 to 25 nm. A noticeable agglomeration occurs with annealing at temperatures higher than $300^{\circ}C$, and higher annealing temperature increases particle size uniformity for the same film thickness sample. Average particle size linearly correlates to the film thickness, but it does not strongly depend on annealing temperature and time, although threshold temperature for complete dewetting increases with an increase of film thickness. Lower annealing temperature develops faceted surface morphology of the silver particles by enhancing the growth of the low index crystal plane of the particles.