• Title/Summary/Keyword: Sol-gel method

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Electrochemical Characteristics of Indium Tin Oxide Nanoparticles prepared by Sol-gel Combustion Hybrid Method

  • Chaoumead, Accarat;Choi, Woo-Jin;Lee, Dong-Hoon;Sung, Youl-Moon
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.414-417
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    • 2011
  • Indium tin oxide (In:$SnO_2$) nanoparticles were synthesized employing a sol-gel combustion method followed by annealing. The TG, XRD, XPS and SEM results of the precursor powders and calcinated In:$SnO_2$ nanoparticles were investigated. Crystal structures were examined by powder XRD, and those results show shaper intensity peak at $25.6^{\circ}$ ($2{\theta}$) of $SnO_2$ by increased annealing temperature. A particle morphology and size was examined by SEM, and the size of the nanoparticles was found to be in the range of 20~30nm. In:$SnO_2$ films could controlled by nanoparticle material at various annealing temperature. The sol-gel combustion method was offered simple and effective route for the synthesis of In:$SnO_2$ nanoparticles.

High-sensitivity ZnO gas Sensor with a Sol-gel-processed SnO2 Seed Layer (Sol-Gel 방법으로 제작된 SnO2 seed layer를 적용한 고반응성 ZnO 가스 센서)

  • Kim, Sangwoo;Bak, So-Young;Han, Tae Hee;Lee, Se-Hyeong;Han, Ye-ji;Yi, Moonsuk
    • Journal of Sensor Science and Technology
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    • v.29 no.6
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    • pp.420-426
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    • 2020
  • A metal oxide semiconductor gas sensor is operated by measuring the changes in resistance that occur on the surface of nanostructures for gas detection. ZnO, which is an n-type metal oxide semiconductor, is widely used as a gas sensor material owing to its high sensitivity. Various ZnO nanostructures in gas sensors have been studied with the aim of improving surface reactions. In the present study, the sol-gel and vapor phase growth techniques were used to fabricate nanostructures to improve the sensitivity, response, and recovery rate for gas sensing. The sol-gel method was used to synthesize SnO2 nanoparticles, which were used as the seed layer. The nanoparticles size was controlled by regulating the process parameters of the solution, such as the pH of the solution, the type and amount of solvent. As a result, the SnO2 seed layer suppressed the aggregation of the nanostructures, thereby interrupting gas diffusion. The ZnO nanostructures with a sol-gel processed SnO2 seed layer had larger specific surface area and high sensitivity. The gas response and recovery rate were 1-7 min faster than the gas sensor without the sol-gel process. The gas response increased 4-24 times compared to that of the gas sensor without the sol-gel method.

The Study on Preparation Parameters of $TiO_2$Catalyst for Photodecomposition of Ethanol as a VOC (VOC물질중 에탄올 광분해반응을 위한 $TiO_2$촉매의 제초변수 고찰)

  • 이병용;김성욱;정석진
    • Journal of Korean Society for Atmospheric Environment
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    • v.17 no.4
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    • pp.363-370
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    • 2001
  • In this study, TiO$_2$, the popular photocatalyst, was used to decompose ethanol. TiO$_2$was prepared by the sol -gel method and coated on pyrex stick. A 15W, UV-A lamp was used as the UV light source and il gas chromatography (HP 5890) was used to confirm the concentrations of ethanol, $CO_2$and the intermediates. Variation of preparation parameters and calcination temperature for TiO$_2$photocatalysts in the sol -gel method caused changes of ethanol decomposition activity. The best ethanol photodecomposition activity was obtained on the sample when prepared with 0.14 mol of HCI, a mol of ethanol and 1.3 mol of TTIP ware mixed in sol-gel process and calcinated at 50$0^{\circ}C$ for 3 hours. Acetaldehyde was detected as an intermediate and decomposed to carbon dioxide and water at the end of the reaction.

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Synthesis and Characterization of Tungsten Trioxide Films Prepared by a Sol-Gel Method for Electrochromic Applications

  • Kim, Tae-Ho;Nah, Yoon-Chae
    • Journal of Powder Materials
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    • v.22 no.5
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    • pp.309-314
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    • 2015
  • Tungsten trioxide thin films are successfully synthesized by a sol-gel method using tungsten hexachloride as precursors. The structural, chemical, and optical properties of the prepared films are characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-Vis spectrophotometry. The electrochemical and electrochromic properties of the films before and after heat treatment are also investigated by cyclic voltammetry, chronoamperometry, and in situ transmittance measurement system. Compared to as-prepared films, heat-treated tungsten trioxide thin films exhibit a higher electrochemical reversibility of 0.81 and superior coloration efficiency of $65.7cm^2/C$, which implies that heat treatment at an appropriate temperature is a crucial process in a sol-gel method for having a better electrochromic performance.

Electrical and Optical Characteristics of X/65/35 (X=6~11) PLZT Thin Films Prepared by Sol-Gel Method (Sol-Gel법으로 제작한 X/65/35 (X=6~11) PLZT 박막의 전기 및 광학 특성)

  • 강종윤;장낙원;백동수;최형욱;박창엽
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.3
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    • pp.237-241
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    • 1998
  • In this study, PLZT stock solutions around x/65/35 (x=6~11) ferroelectric region were prepared by Sol-Gel method and deposited on ITO-glass by spin-coating method. The thin films were annealed by RTA(rapid thermal annealing). The variations of crystallographic structure of the thin films were observed using XRD and hysteresis curves, dielectric characteristics, and optical transmittances were measured in order to investigate the characteristics of the thin films. The thin films were crystallized at $750^{\circ}C$ for 5 min by RTA. Relative dielectric constant and optical transmittance increased with increasing La content, Ec and Pr were higher for thin films than for bulk materials.

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Preparation of $\gamma-LiAlO_2$ Short Fibers by the Sol-Gel Method (졸-겔법에 의한 $\gamma-LiAlO_2$ 단섬유의 제조)

  • 현상훈;이재현;홍성안
    • Journal of the Korean Ceramic Society
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    • v.33 no.10
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    • pp.1079-1088
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    • 1996
  • Discontinuous ${\gamma}$-LiAlO2 fibers for fiber-reinforcing MCFC matrixes have been produced by the sol-gel process using the centrifugal spinning apparatus of the Rotary type. Gel fibers could be obtained through spinning of stable LiAlO2 complex polymetric sols under the optimum spinning conditions (hollow-disc rotating velocity 9000 rpm sol feeding rate of 4ml/min flowing N2 temperature of 4$0^{\circ}C$ and flowing N2 pressure of 4 bar). It was found that defect free and densified ${\gamma}$-LiAlO2 fibers with the relative density of 98% and the mean diameter of 4.7${\mu}{\textrm}{m}$ were prepared when the spinned fibers were heat-treated to 100$0^{\circ}C$ on the specified heating schedule. in particular the mean diameter and length of fibers could be controlled by the pressure of flowing N2 and the chopping-sieving method respectively.

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A Study on Structural and Dielectric Properties of the ((Ba,Sr)TiO$_3$ Thin Films by Sol-Gel Method (Sol-Gel법으로 제작된 (Ba,Sr)O$_3$ 박막의 구조 및 유전특성에 관한 연구)

  • 홍상기;김성구;마석범;장낙원;백동수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.290-293
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    • 1999
  • (Ba$_{0.5}$Sr$_{0.5}$)TiO$_3$ thin films were fabricated at different RTA temperatures and thicknesses by Sol-Gel method. Solution consisting of acetate powders and titanium isopropoxide in a mixture of acetic acid and ethylene glycol were spin coated onto Pt/Ti/SiO$_2$/Si substrates. The films were annealed in the temperature range of 650~80$0^{\circ}C$ for 3 minutes by rapid thermal annealing. These BST thin films were fully crystallized at 75$0^{\circ}C$ and showed a maximum dielectric constant value of $\varepsilon$$_{r}$=~468 and dielectric loss was ~0.025 at a thickness of approximately 4000$\AA$.EX>.>.

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Preparation of Glass-Ceramics in $Li_2O-Al_2O_3-TiO_2-SiO_2$ System by Sol-Gel Technique : (II) Crystallization of $Li_2O-Al_2O_3-TiO_2-SiO_2$ Monolithic Gel Prepared by Sol-Gel Method (Sol-Gel 법에 의한 $Li_2O-Al_2O_3-TiO_2-SiO_2$ 계 다공성 결정화 유리의 제조 : (II) Sol-Gel 법에 의해 제조된 $Li_2O-Al_2O_3-TiO_2-SiO_2$ 계 괴상겔의 결정화)

  • 조훈성;양중식
    • Journal of the Korean Ceramic Society
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    • v.32 no.4
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    • pp.507-515
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    • 1995
  • The monolithic dry gels of the Li2O-Al2O3-TiO2-SiO2 system were prepared by the sol-gel technique using metal alkoxides as starting materials to obtain monolithic glass-ceramics at low temperature without melting. Activation energy for the crystal growth of the gel with 6.05% TiO2, nucleating ageng, for the preparation of Li2O-Al2O3-TiO2-SiO2 system glass-ceramic was 101.14kcal/mol. As a result of the analysis of DTA & XRD, it was confirmed that the crytallization of Li2O-Al2O3-TiO2-SiO2 system glass-ceramic was the most efficient when 6.05% TiO2, nucleating agent, was added. $\beta$-eucryptite solid solution crystals and $\beta$-spodumene solid solution crystals were detected in the sample heat treated above 85$0^{\circ}C$. The sintered gel heat treated at 85$0^{\circ}C$ had the specific surface area of 185$m^2$/g, the pore volume of 0.19cc/g and the average pore radius of 20.8$\AA$. This shows that the sintered gel is also comparatively porous material. In temperature range of 25~85$0^{\circ}C$ thermal expansion coefficient of the specimen which was crystallized for 10hrs at 85$0^{\circ}C$ was 6.7$\times$10-7/$^{\circ}C$, which indicated that the crystallized specimen was turned out to be the glass-ceramic with low thermal expansion.

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Electrochemical Characteristics of TiO2 Photoelectrode for DSSC Prepared by Sol-gel Method (졸겔법에 의한 DSSC 광전극의 전기화학적 특성)

  • Park, A-Reum;Jin, En Mei;Gu, Hal-Bon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.4
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    • pp.315-320
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    • 2012
  • In general, a photoelectrode in DSSC(dye sensitized solar cell) are fabricated by using the $TiO_2$ (Titanium dioxide) to realize high efficiency and the efficiency of DSSC is affected by the size, the shape and the property of $TiO_2$. We synthesized the crystalline $TiO_2$ by sol-gel method. In spite of many merits, only weakness for the sol-gel method is taking many process times. To solve this problem, we reduced the fabricating processes. The reduced process is the making process that is $TiO_2$ sol to $TiO_2$ powder with including of two heat treatment and two mixing. We could simplify the process by preparing $TiO_2$ sol to $TiO_2$ paste directly. As a result, DSSC fabrication process is simplified and we have obtained the efficiency best result 3.88% with $V_{OC}$=0.71 V, $J_{SC}=8.70\;mA/cm^{-2}$, and FF=62.37%, respectively.

Fabrication of ITO Thin Film by Sol-Gel Method (Sol-Gel 법을 이용한 ITO박막의 제조)

  • Kim Gie-Hong;Lee Jae-Ho;Kim Young-Hwan
    • Journal of the Korean Electrochemical Society
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    • v.3 no.1
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    • pp.11-14
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    • 2000
  • Transparent conducting ITO thin films have been studied and developed for the solar cell substrate or LCD substrate. ITO thin film has been mostly fabricated by high cost sputtering method. In this research, sol-gel method is applied to fabricate ITO thin film at lower cost. The research is focused on the establishment of process condition and development of precursor. Organic sol was made of indium tri-isopropoxide dissolved in ethylene glycol monoethyl ether. The hydrolysis was controled by addition of acetyl acetone. Tin(IV) chloride was added as dopant. Inorganic sol was made of indium acetate dissolve din normal propanol. Spin coating technique was applied to coat ITO on borosilicate glass. The resistivity of ITO thin film was approximately $0.01\Omega{\cdot}cm$ and the transmittance is higher than $90\%$ in a visible range.