• 한국세라믹학회지
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• 제33권12호
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• pp.1301-1310
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• 1996

Generally it requires high sintering temperatures more than 135$0^{\circ}C$ to make semiconductive BaTiO3 ceramics. Also it is very difficult to achieve a homogeneous mixing in solid-state reaction method. Therefore the liquid phase distributed to non-uniform dilute the characteristics of PTCR. In order to improve the uniformity this study is used the sol-gel coating method. Using this method we studied the new manufacturing process that had a high reproducibility and mass production capability. Tetraethyl orthosilicate (TEOS) was used as a source of Si. The semiconductive BaTiO3 ceramics which was produced by sol-gel method for the SiO2 addition and sintered between 124$0^{\circ}C$ and 130$0^{\circ}C$ showed almost same resistivity at room temperature among 125$0^{\circ}C$ and 130$0^{\circ}C$. As the results We could be sintered the semiconducting BaTiO3 ceramics at lower temperature even at 125$0^{\circ}C$ maintaining the same specific resistivity ratio ($\rho$max/$\rho$min) at 130$0^{\circ}C$. The specific resistivity both below and above the Curie temperature were increased by slow cooling and the steepness of the plots in the reasion of transition from low to high resistance increased as the cooling rate decreased.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.232-233
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• 2006

In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.477-480
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• 1998

Sol-gel processing, which started some decades back as a laboratory curiosity, has proved to be a powerful and versatile technique for the synthesis of materials. The utility of the sol-gel method for producing glass and ceramic materials in the form of powders, fibers, thin films and bulk shapes with high purity, functional microstructures and potentially high chemical homogeneity at relatively low temperature (compared to conventional processing) has been discussed.

• Transactions on Electrical and Electronic Materials
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• 제18권3호
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• pp.155-158
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• 2017

In this paper, ZnO Thin Film Transistors (TFTs) were fabricated by a sol-gel method using a low-temperature process, and their physical and electrical characteristics were analyzed. To lower the process temperature to $200^{\circ}C$, we used a zinc nitrate hydrate ($Zn(NO_3)_2{\cdot}xH_2O$) precursor. Thermo Gravimetric Analyzer (TGA) analysis showed that the zinc nitrate hydrate precursor solution had 1.5% residual organics, much less than the 6.5% of zinc acetate dihydrate at $200^{\circ}C$. In the sol-gel method, organic materials in the precursor disrupt formation of a high-quality film, and high-temperature annealing is needed to remove the organic residuals, which implies that, by using zinc nitrate hydrate, ZnO devices can be fabricated at a much lower temperature. Using an X-Ray Diffractometer (XRD) and an X-ray Photoelectron Spectrometer (XPS), $200^{\circ}C$ annealed ZnO film with zinc nitrate hydrate (ZnO (N)) was found to have an amorphous phase and much more oxygen vacancy ($V_o$) than Zn-O bonds. Despite no crystallinity, the ZnO (N) had conductance comparable to that of ZnO with zinc acetate dihydrate (ZnO (A)) annealed at $500^{\circ}C$ as in TFTs. These results show that sol-gel could be made a potent process for low-cost and flexible device applications by optimizing the precursors.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1733-1736
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• 2008

ZnO thin films with preferred orientation along the (0 0 2) plane were fabricated by a sol-gel method. The effects of the annealing temperature, time, and thickness were studied by investigating UV-visible spectra, FT-IR spectra, and XRD of ZnO films. The films were dried and annealed ed at $100^{\circ}C,\;200^{\circ}C$, and $300^{\circ}C$ for 1hr, 2hrs, and 3hrs, respectively. The film showed the preferred (0 0 2) orientation and high transmittance near 90% in the visible range. Also, SEM images of the films exhibited very smooth surfaces without holes and cracks. Schottky diodes were fabricated by using ZnO sol-gel material. Au and Al were used as electrodes to make Ohmic and Schottky contacts, respectively. The annealing temperature, time and the thickness dependent I-V characteristics were presented in this article.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1078-1084
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• 2002

The formation temperature for the perovskite lead zirconate titanate [Pb(Zr,Ti)O3, PZT] derived from sol-gel route was lowered by more than $100^{\circ}C$ with the addition of crystallographically suitable seed particles, such as barium titanat e (BT) or PZT. We investigated the effect of seeding on the crystallization of perovskite phase and in the microstructure of the sol-gel derived PZT powder by varying the concentration, size and chemical species of seed particles. The phase transition as a function of temperature was monitored by DTA, XRD, and Raman spectroscopy, and the interface between the seed particle and grown PZT layer was analyzed by SEM and high resolution TEM techniques. It was found that both the heterogeneous and homogeneous nucleation contributes competitively in the formation of perovskite PZT grains.

• 멤브레인
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• 제11권3호
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• pp.124-132
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• 2001

고온에서 수소 분리 회수를 목적으로 silica/alumina 복합 막을 합성하였다. 막의 선택 투과 성능을 향상시키기 위해, sol-gel법에 의한 silica 및 alumina층을 중간층으로 도입하고, 그 위에 강제유동 CVD법에 의한 silica를 합성하였다. Sol-gel법에 의해 ${\alpha}$-alumina tube에 합성한 ${\gamma}$-alumina 및 silica 막은 Knudsen 확산 영역의 많은 mesopore를 포함하고 있어서 수소 선택 분리 막으로는 적합하지 못했다. 하지만, sol-gel법에 의해 합성한 silica/${\gamma}$-alumina층에 강제유동 CVD법으로 silica를 합성한 결과, 질소 투과 영역의 세공이 완전히 제거되어, 높은 수소 선택성을 가지는 복합 막이 형성되었다. 그 막은 온도에 따라 수소 투과 속도가 증가하여 $450^{\circ}C$에서 $5.57{\times}10^{-8}molm^2s^LPa^1$의 수소 투과 속도와, 9.52 kJ/mol의 활성화 에너지를 나타냈다. 분자체 효과에 의해 질소 투과가 완전히 배제되고, 수소만 선택적으로 투과되는 silica/alumina 복합막이 성공적으로 합성된다.

• Current Photovoltaic Research
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• 제2권3호
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• pp.110-114
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• 2014

We propose a low temperature sol-gel ZnO/Ag nanowire composite thin film to fulfill low temperature and low cost requirements, which are essential criteria in future flexible electronic devices. In this proposed thin film, Ag nanowire plays the role of electrical conduction, and sol-gel ZnO provides a structural medium with a high visible transmittance. Low temperature restriction in the sol-gel fabrication process prevents sufficient oxidation of Zn acetate precursors, which were solved by a post-coating treatment with ultraviolet light irradiation. Composite thin film formation was performed by spin coating methods with a mixed precursor solution or in a sequential manner. We obtained an average visible transmittance larger than 85% and a sheet resistance smaller than $50{\Omega}/sq$. After optimization in a fabricated composite transparent conductive thin film with the thickness around 100 nm. Similar experimental demonstration in a flexible substrate (polyethyleneterephthalate) was successful, which implies a promising application opportunity of this technology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.271-278
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• 2006

Green light emitting $Zn_2SiO_4$Mn and Al co-doped $Zn_2SiO_4$:Mn phosphor were synthesized by a sol-gel method combined with a furnace firing. The luminescent properties of the sample have been investigated. We have found that the phosphor powder with uniform shape show the maximum luminescent intensity when it is prepared with sol-gel method and fired at relatively high temperature ($1100{\sim}1300^{\circ}C$).

• 한국세라믹학회지
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• 제33권4호
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• pp.432-440
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• 1996

본 연구는 졸-겔법을 이용하여 알칼리 조건인 pH 10에서 제조한 ZrO2의 하소온도에 따른 분말특성과 코발트 흡착량에 미치는 하소온도의 영향에 대하여 검토하였다. 졸-겔법을 이용하여 ZrO2 분말을 제조하고, 600, 800, 1000, 1200, 140$0^{\circ}C$로 하소한 후, X-선 회절법, SEM, BET 방법, Fourier transform 적외선(FT-IR), 열중량 및 열시차분석법(TG-DTA)등을 이용하여 특성을 분석하였다. 알칼리조건인 pH 10에서 제조한 ZrO2는 하소온도가 $600^{\circ}C$일때 고온수에서 코발트 흡착량이 가장 우수하였으며, 이때 $600^{\circ}C$로 하소한 ZrO2의 비표면적은 24.03m2/g이였으며 25$0^{\circ}C$의 고온수에서 코발트 흡착량은 0.16m-eq/g이였다.