• Title, Summary, Keyword: Microwave microscopy

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Studying the influence of the concentration of alkaline solution to the formation of TiO2 nanotube prepared by microwave-assisted hydrothermal method

  • Hao, Nguyen Huy;Cho, Sung Hun;Lee, Soo W.
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.260-261
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    • 2014
  • $TiO_2$ nanotubes (TNT) synthesized by microwave-assisted hydrothermal method by using $TiO_2-P25$ as a precursor at hydrothermal temperature $150^{\circ}C$ in 4 hours. The concentration of alkaline solution is between 4M and 10M. Samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and UV-vis DRS spectroscopy. The results demonstrated the effects of the alkali concentration to the formation of nanotubes. The photocatalytic activity was investigated by degradation of Methylene Blue (MB).

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Study on the Detoxification of Asbestos-Containing Wastes (ACW) Using SiC Plate (SiC 플레이트를 이용한 석면 함유 폐기물의 무해화 연구)

  • Hong, Myung Hwan;Choi, Hyeok Mok;Joo, So Young;Lee, Chan Gi;Yoon, Jin-Ho
    • Journal of the Korean Institute of Resources Recycling
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    • v.29 no.1
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    • pp.35-42
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    • 2020
  • Even asbestos-containing waste (ACW) are highly harmful to humans, it continues being produced due to the massive disposal of asbestos-containing products. A development of asbestos detoxification and recycling technologies is required. Heat treatment using microwave is the most efficient method for ACW detoxification. However, microwave heat treatment method has the limitation that asbestos does not absorb microwave at room temperature. That is why, in this study, ACW was detoxified by microwave heat treatment adding the ACW between SiC plates, which are inorganic heating elements that absorb microwaves at room temperature. In order to improove the heat transfer, ACW was crushed and pulverized and then heated using microwave. Microwave heat treatment temperature and time variables were adjusted to investigate the detoxification properties according to heat treatment conditions. After heat treatment, treated ACW was analyzed for detoxification properties through crystal structure and microstructure analysis using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microwave heat treatment method using SiC plate can be heated up to the target temperature within a short time. Finally, complete asbestos detoxification was confirmed from the crystal structure and the microstructure when the microwave heat treatment was performed at 1,200℃ for at over 60 minutes and at 1,300℃ for at over 10 minutes.

Field Emission Characteristics of Deffctive Diamond Films

  • Koh, Ken-Ha;Park, Kyung-Ho;Lee, Soon-Il
    • Journal of the Korean Vacuum Society
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    • v.7 no.s1
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    • pp.160-166
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    • 1998
  • The field emission characteristics of defective diamond films grown by microwave plasma enhanced chemical vapor deposition (MPECVD) have been studied. X-ray diffraction, the poor crystal quality and/or small grain sizes of the diamond phase and the inclusion of the non-diamond carbon phases in these films have been condirmed by raman spectroscopy, scanning electron microscopy, atomic force microscopy, and the reflectance measurements. The degrees of the film defectiveness and the emission characteristics were dependent on the methane concentration. Current-versus-voltage measurements have demonstrated that the defective diamond films have good electron emission characteristics. characteristics strongly suggests the defect-related electron-emission mechanism. The defective diamond films deposited on Si substrates show the field emission current density of 1$\mu\textrm{A}/\textrm{cm}^2$ and 1mA/$\textrm{cm}^2$ have been measured at electric fields as low as 4.5V/$\mu\textrm{m}$ and 7.6V/$\mu\textrm{m}$, respectively. We also observed the similar emission characteristics from the defective diamond film deposited on Cr/Si substrate and could decrease the deposition temperature to $600^{\circ}C$.

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Photocatalytic Performance of CoS2-Graphene-TiO2 Ternary Composites for Reactive Black B (RBB) Degradation

  • Ali, Asghar;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
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    • v.54 no.4
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    • pp.308-313
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    • 2017
  • In this study we examined the photo-degradation efficiency of $CoS_2-G-TiO_2$ nanocomposites under visible light irritation using Reactive Black B (RBB) as standard dye, $CoS_2-G-TiO_2$ nanocomposites synthesized by facial microwave assist technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopic analysis. Our results show the efficiency of the $CoS_2-G-TiO_2$ ternary nanocomposite is better than $CoS_2-G$ and $TiO_2-G$ nanocomposite. The degradation efficiency of $CoS_2-G-TiO_2$ nanocomposite was found approximately 89% of Reactive Black B (RBB) degraded after 180 min. Our results will open new way for the development of a new ternary nanocomposite photocatalytic application.

Solid Particle Erosion of CVD Diamond (CVD 다이아몬드 코팅의 고체입자 Erosion 특성)

  • 김종훈;임대순
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.69-73
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    • 1997
  • Microwave Plasma assisted CVD (Chemical Vapor Deposition) and DC Plasma CVD were used to prepare thin and thick diamond film, respectively. Diamond coated silicon nitride and fiee standing diamond thick film were eroded by silicon carbide particles. The velocity of the solid particle was about 220m/sec. Phase transformation and the other crack formation were investigated by using Raman spectroscopy and microscopy.

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Microwave Dielectric Characteristics of Ba(Mg1/3Nb2/3)O3-La(Mg2/3Nb1/3)O3 Ceramics with Crystal Structure (결정 구조에 따른 Ba(Mg1/3Nb2/3)O3-La(Mg2/3Nb1/3)O3세라믹스의 마이크로파 유전 특성)

  • Paik, Jong-Hoo;Lim, Eun-Kyeong;Lee, Mi-Jae;Jee, Mi-Jung;Choi, Byung-Hyun;Kim, Sei-Ki
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.1
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    • pp.30-37
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    • 2005
  • The microwave dielectric properties and their related structural characteristics in solid solutions of (1-$\chi$) Ba($Mg_{1/3}$Nb$_{2/3}$) $O_3$-$\chi$La(Mg$_{2/3}$Nb$_{1}$3) $O_3$(BLMN) have been investigated by measuring the dielectric constant($\varepsilon$r), Q value and temperature coefficient of resonant frequency($\tau$f) and by observing the crystal structure using high resolution transmission electron microscopy (HRTEM). Microwave dielectric properties showed characteristic features for specific composition. Dielectric constant($\varepsilon$$_{r}$) showed maximum value at the composition which corresponds to the phase boundary between 1 : 2 ordered and 1 : 1 ordered structure. The increase in $\varepsilon$$_{r}$ may be caused by the rattling of ions by incorporating smaller ions and the disordered structure. The variation of temperature coefficient of resonant frequency($\tau$$_{f}$) was investigated in terms of oxygen octahedra tilting.dra tilting.

The study for fabrication and characteristic of Li$_2$O-2SiO$_2$conduction glass system using conventional and microwave energies (마이크로파와 재래식 열원을 이용한 고체 전지용 Li$_2$O-2SiO$_2$계 전도성 유리의 제조 및 특성에 관한 연구)

  • Park, Seong-Soo;Kim, Kyoung-Tae;Kim, Byoung-Chan;Park, Jin;Park, Hee-Chan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.10 no.1
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    • pp.66-72
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    • 2000
  • The behavior of nucleation and crystallization in the $Li_2O_3-SiO_2$ glass heat-treated at different condition under the conventional and microwave processing was studied by differential thermal analysis (DTA), X-ray diffractometry (XRD), optical microscopy (OM), and electrical conductivity measurement. Nucleation temperature and temperature of maximum nucleation rate in both conventionally and microwave heat-treated samples were 460~$500^{\circ}C$ and $580^{\circ}C$, respectively. It was expected that the probability for bulk crystallization increased in microwave heat-treated sample, compared to conventionally heat-treated one. Degree of crystallization increased with increasing crystallization temperature in both conventionally and microwave heat-treated samples. However, pattern of crystallization growth under microwave processing appeared to be quite different from that under the conventional one due to its internal or volumetric heating. Electrical conductivity of conventionally and microwave heat-treated samples were 1.337~2.299, 0.281~~$0.911{\times}10^{-7}\Omega {\textrm}{cm}^{-1}$, respectively.

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Surface Modification with Atmospheric Microwave Agron Plasma Jet Assisted with Admixture of H2O2 and Analysis of Plasma Characteristics

  • Won, I.H.;Shin, H.K.;Kwon, H.C.;Kim, H.Y.;Kang, S.K.;Lee, J.K.
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.544-545
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    • 2013
  • Recently, low-temperature atmospheric-pressure plasmas have been investigated [1,2] for biomedical applications and surface treatments. Experiments for improving hydrophilicity of stainless steel (SUS 304) plate with atmospheric microwave argon and H2O2 mixture plasma jet [3] were carried out and experimental measurements and plasma simulations were conducted for investigating the characteristics of plasma for the process. After 30 s of low power (under 10 W) and low temperature (under $50^{\circ}C$) plasma treatment, the water contact angle decreased rapidly to around $10^{\circ}$ from $75^{\circ}$ and was maintained under $30^{\circ}$ for a day (24 hours). The surface free energy, calculated from the contact angles, increased. The chemical properties of the surface were examined by X-ray Photoelectron Spectroscopy (XPS) and the surface morphology and roughness were examined by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) respectively. The characteristics of plasma sources with several frequencies were investigated by Optical Emission Spectroscopy (OES) measurement and one-dimensional Particle-in-Cell (PIC) simulation and zero-dimensional global simulation [4]. The relation between plasma components and the efficacy of the surface modification were discussed.

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Photocatalytic Dye Decomposition Effect of Binary Copper (I) Selenide-graphene Nanocomposites Synthesized with Facile Microwave-assisted Technique (용이한 마이크로웨이브 조사법을 사용하여 합성한 이원계 Cu (I) 셀렌 그래핀 나노복합체의 광촉매 염료분해 효과)

  • Ali, Asghar;Oh, Won-Chun
    • Applied Chemistry for Engineering
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    • v.27 no.5
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    • pp.483-489
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    • 2016
  • Here, we examined the photo-degradation efficiency of $Cu_2Se$-graphene nanocomposites synthesized by a facile and fast microwave-assisted technique. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, XPS and UV-Vis spectrophotometry. The photocatalytic performance was studied through the decomposition of Rhodamine (Rh B) as a standard dye under visible light radiation. A 95% of Rh B degradation after visible light irradiation for 180 min indicates that the $Cu_2Se$-graphene composite exhibited significant photodegradation efficiency. Therefore, it can be concluded that the synthesized $Cu_2Se$-graphene can be used as a suitable catalyst for decomposing dye pollutants.

Synthesis and characterization of polypyrrole doped by cage silsesquioxane with carboxyl groups

  • Shi, Gang;Che, Youxin;Wu, Luyan;Rong, Yao;Ni, Caihua
    • The Korean Journal of Chemical Engineering
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    • v.34 no.2
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    • pp.470-475
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    • 2017
  • Cage silsesquioxane with carboxyl groups (POSS-COOH) was successfully synthesized, after which it was added to polypyrrole (PPy) as a dopant to produce the doped PPy (PPy/POSS-COOH) solution. The PPy/POSS-COOH composites were characterized by FTIR (Fourier transformation infrared spectroscopy), SEM (Scanning electron microscopy), TGA (Thermo-gravimetric analysis), CV (Cyclic voltammetry) and RL (Reflection loss). Compared to PPy without POSS-COOH (un-PPy), the conductivity of PPy/POSS-COOH composites could be improved dramatically, reaching up to 0.850 S/cm at $25^{\circ}C$. Under $N_2$ atmosphere, the residual rate of PPy/POSS-COOH was 68% at $700^{\circ}C$, 14% higher than the one of un-PPy. Meanwhile, PPy/POSS-COOH had a reflection loss below -8 dB over 9.35 to 11.20 GHz, with a minimum value of -10.32 dB at 10.54 GHz, thus demonstrating higher microwave absorption than un-PPy. This method may provide a facile route to produce doped conducting polymers with POSS-COOH.