• Title/Summary/Keyword: Sol-gel

Search Result 2,378, Processing Time 0.301 seconds

Structural and Opical Properties of ZnO Thin Films with Different Temperature of Sol-gel Solution (Sol-gel 용액의 온도변화에 따른 ZnO 박막의 구조적, 광학적 특성)

  • Park, Hyeong-Gil;Nam, Gi-Ung;Yun, Hyeon-Sik;Kim, So-A-Ram;Im, Jae-Yeong
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • /
    • pp.137-138
    • /
    • 2012
  • ZnO 박막을 Sol-gel용액을 이용한 스핀코팅 방법으로 석영기판 위에 성장하였고 Sol-gel 용액의 온도 변화에 따른 구조적, 광학적 특성을 분석하였다. ZnO 박막의 구조적, 광학적 특성을 조사하기 위해 field-emission scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), 그리고 ultraviolet-visible (UV) spectroscopy을 사용하였다. PL 분석에서 ZnO 박막은 orange 계열의 발광을 하였으며, PL spectra는 3.3 eV 부근의 near-band edge emission (NBE) 피크와 2.0 eV 부근의 deep-level emission (DLE) 피크로 이루어져있다. 모든 sol-gel 용액 온도에서, DLE 피크가 NBE 피크보다 더 우세하고 이 DLE 피크는 sol-gel 용액의 온도가 증가함에 따라 점점 증가하다가 감소하는 것을 알 수 있다. 이런 DLE 피크는 산소 공공, 아연 공공, 침입형 산소, 침입형 아연 등과 같은 결함에 의한 것이며, ZnO 박막은 sol-gel 용액의 온도에 따라 결함의 특성이 변화하였다.

  • PDF

Development of Hybrid Sol-Gel Coating to Prevent Corrosion of Magnesium Alloys (마그네슘 합금의 방청을 위한 하이브리드 졸-겔 코팅제의 개발)

  • Lee, Dong Uk;Kim, Young Hoon;Moon, Myung Jun
    • Corrosion Science and Technology
    • /
    • v.17 no.1
    • /
    • pp.30-36
    • /
    • 2018
  • The high rate of corrosion of magnesium alloys makes it limited for industrial applications. Therefore, surface treatment is required to enhance their corrosion resistance. In our study, a chemical conversion coating for protecting the corrosion of the magnesium alloy, AZ31B, was prepared by using a phosphate-permanganate solution. The chemical conversion coating had a limited protection ability due to defects arising from cracks and pores in the coating layer. The sol-gel coating was prepared by using trimethoxymethylsilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors, and aluminum acetyl acetonate as a ring opening agent. The corrosion protection properties of sol-gel and conversion coatings in 0.35wt% NaCl solution were measured by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The EIS results indicated that the resistance of the chemical conversion coating with the sol-gel coating was significantly improved through the sol-gel sealed phosphate-permanganate conversion coating. The results of the potentiodynamic polarization test revealed that the sol-gel coating decreased the corrosion current density ($I_{corr}$). The SEM image showed that the sol-gel coating sealed conversion coating and improved corrosion protection.

Preparation and Characteristics of PLT(28) Thin Film Using Sol-Gel Method (Sol-Gel 법을 이용한 PLT(28) 박막의 제작과 특성)

  • Kang, Seong-Jun;Joung, Yang-Hee;Yoo, Jae-Hung
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • v.9 no.2
    • /
    • pp.865-868
    • /
    • 2005
  • We fabricated the $Pb_{0.72}La_{0.28}TiO_3 (PLT(28))$ thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of 100% perovskite phase by drying at 350$^{\circ}C$ after each coating and final annealing at 650$^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the Pt/Ti/SiO$_2$/Si substrate and its dielectric constant and leakage current density were measured as 936 and 1.1${\mu}$A/cm$^2$, respectively

  • PDF

Preparation and Characteristics of PLT(28) Thin Film Using Sol-Gel Method (Sol-Gel 법을 이용한 PLT(28) 박막의 제작과 특성)

  • Kang Seong Jun;Joung Yang Hee;Yoo Jae-hung
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.9 no.7
    • /
    • pp.1491-1496
    • /
    • 2005
  • We fabricated the $Pb_{0.72}La_{0.28}TiO_3$ (PLT(28)) thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of $100\%$ perovskite phase by drying at $350^{\circ}C$ after each coating and final annealing at $650^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the $Pt/Ti/SiO_2/Si$ substrate and its dielectric constant and leakage current density were measured as 936 and $1.1{\mu}A/cm^2$, respectively.

Properties of Nano-Hybrid Coating Films Synthesized from Colloidal Silica-Silane (콜로이달 실리카와 실란으로부터 합성된 나노하이브리드 코팅 박막의 특성)

  • Na, Moon-Kyong;Ahn, Myeong-Sang;Kang, Dong-Pil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.232-233
    • /
    • 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.

  • PDF

Effective Positive Bias Recovery for Negative Bias Stressed sol-gel IGZO Thin-film Transistors (음 바이어스 스트레스를 받은 졸-겔 IGZO 박막 트랜지스터를 위한 효과적 양 바이어스 회복)

  • Kim, Do-Kyung;Bae, Jin-Hyuk
    • Journal of Sensor Science and Technology
    • /
    • v.28 no.5
    • /
    • pp.329-333
    • /
    • 2019
  • Solution-processed oxide thin-film transistors (TFTs) have garnered great attention, owing to their many advantages, such as low-cost, large area available for fabrication, mechanical flexibility, and optical transparency. Negative bias stress (NBS)-induced instability of sol-gel IGZO TFTs is one of the biggest concerns arising in practical applications. Thus, understanding the bias stress effect on the electrical properties of sol-gel IGZO TFTs and proposing an effective recovery method for negative bias stressed TFTs is required. In this study, we investigated the variation of transfer characteristics and the corresponding electrical parameters of sol-gel IGZO TFTs caused by NBS and positive bias recovery (PBR). Furthermore, we proposed an effective PBR method for the recovery of negative bias stressed sol-gel IGZO TFTs. The threshold voltage and field-effect mobility were affected by NBS and PBR, while current on/off ratio and sub-threshold swing were not significantly affected. The transfer characteristic of negative bias stressed IGZO TFTs increased in the positive direction after applying PBR with a negative drain voltage, compared to PBR with a positive drain voltage or a drain voltage of 0 V. These results are expected to contribute to the reduction of recovery time of negative bias stressed sol-gel IGZO TFTs.

Coloration of Glasses with Squarylium Dye by Sol-Gel Process (Sol-Gel법을 이용한 Squarylium색소의 유리착색)

  • 김성훈;한선경;송경헌;임용진
    • Textile Coloration and Finishing
    • /
    • v.6 no.1
    • /
    • pp.49-53
    • /
    • 1994
  • The transparent coloration of glasses has been successfully achieved by coated glass surface with squarylium dye by the sol-gel colored coating method. Treatment of sol-gel colored coating layer with HCI(g) greatly decreases the absorbance at λ$_{max}$, that increases exposure to $NH_{3}$(g) and the reversible color-colorless responce was extremely rapid.d.

  • PDF

A comparative study of physical properties of $TiO_2$ thin films according to a coating method on orthodontic wires and brackets (교정용 와이어 및 브라켓에 이산화티탄 광촉매 코팅 시 코팅방법에 따른 비교연구)

  • Koh, Eun-Hee;Cho, Jin-Hyoung
    • The korean journal of orthodontics
    • /
    • v.36 no.6
    • /
    • pp.451-464
    • /
    • 2006
  • The purpose of this study was to search for an appropriate method of coating $TiO_2$ on orthodontic appliances. $TiO_2$ thin films were deposited on orthodontic wires and brackets using sol-gel, CVD (Chemical Vapor Deposition) and PE-CVD (Plasma Enhanced-CVD) methods. The roughness of $TiO_2$-coated surfaces was investigated via scanning electron microscope (SEM) and adhesive strength of $TiO_2$ thin films was measured by adhesive tape pull test. Methylene blue degradation test was carried out to evaluate the photocatalytic activity of $TiO_2$ and the corrosion resistance of $TiO_2$ thin films against fluoride solution was also analyzed by observing the surfaces of $TiO_2$-coated wires and brackets via SEM after immersion in sodium fluoride solution. Through the comparison of properties and photocatalytic activity of $TiO_2$ thin films according to the coating methods, the following results were obtained. Smoother surfaces of $TiO_2$ thin films were generated by CVD or PE-CVD methods than through the sol-gel method or the control. Adhesive strength of the $TiO_2$ thin films was highest in PE-CVD and gradually became lower in the order of CVD, then the sol-gel method. Photocatalytic activity of $TiO_2$ thin films on methylene blue was the highest in PE-CVD and gradually became lower in the order of CVD, then the sol-gel method. Corrosion resistance of $TiO_2$ thin films against fluoride solution was stronger in CVD and PE-CVD methods than in the sol-gel method. The results of this study suggest that the CVD or PE-CVD methods is more appropriate than the sol-gel method for $TiO_2$ coating on orthodontic wires and brackets.

Synthesis of Silica/Alumina Composite Membrane Using Sol-Gel and CVD Method for Hydrogen Purification at High Temperature (Sol-gel 및 CVD법을 이용한 고온 수소 분리용 silica/alumina 복합막의 합성)

  • 서봉국;이동욱;이규호
    • Membrane Journal
    • /
    • v.11 no.3
    • /
    • pp.124-132
    • /
    • 2001
  • Silica membranes were prepared on a porous ${\alpha}$-alumina tube with pore size of 150nm by sol-gel and chemical vapor deposition(CVD) method for hydrogen separation at high temperatures. Silica and ${\gamma}$-lumina membranes formed by the sol-gel method possessed a large amount of mesopores of a Knudsen diffusion regime. In order to improve the $H_2$ selectivity, silica was deposited in the sol-gel derived silica/${\gamma}$-alumina layer by thermal decomposition of tetraethyl orthosilicate(TEOS) at $600^{\circ}C$. The CVD with forced cross flow through the porous wall of the support was very effective in plugging mesopores that were left unplugged in the membranes. The CVD modified silica/alumina composite membrane completely rejected nitrogen permeation and thus showed a high $H_2$ selectivity by molecular sieve effect. the permeation of hydrogen was explained by activated diffusion and the activation energy was 9.52kJ/mol.

  • PDF

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
    • /
    • v.29 no.6
    • /
    • pp.420-426
    • /
    • 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.