• Title, Summary, Keyword: Microwave microscopy

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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.

GROWTH OF CARBON NANOTUBES ON GLASS BY MICROWAVE PLASMA CHEMICAL VAPOR DEPOSITION (마이크로웨이브 플라즈마 화학기상증착장비를 사용한 유리기판상의 탄소나노튜브의 합성)

  • Lee, Jae-Hyeoung;Choi, Sung-Hun;Choi, Won-Seok;Hong, Byung-You;Kim, Jeong-Tae;Lim, Dong-Gun;Yang, Kea-Joon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.99-100
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    • 2005
  • We have grown carbon nanotubes (CNTs) with a microwave plasma chemical vapor deposition (MPECVD) method, which has been regard as one of the most promising candidates for the synthesis of CNTs due to the vertical alignment, the low temperature and the large area growth. We use methane ($CH_4$) and hydrogen ($H_2$) gas for the growth of CNTs. 60 nm thick Ni catalytic layer were deposited on the TiN coated glass substrate by RF magnetron sputtering method. In this work, we report the effects of pressure on the growth of CNTs. We have changed pressure of processing (10 $\sim$ 20 Torr) deposition of CNTs. SEM (Scanning electron microscopy) images show diameter, length and cross section state CNTs.

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Preparation of Poly(ethylene naphthalate) Film Coated with Silicones for High Temperature Insulator (실리콘 코팅을 이용한 poly(ethylene naphthalate) 고온용 방열 필름의 제조)

  • Lee, Soo;Na, Cha-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.24 no.2
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    • pp.167-173
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    • 2007
  • The surface of poly(ethylene naphthalate) film applicable to high temerature insulator for convection microwave oven was modified with silicone coating solutions in the presence of silane crosslinking agent. The structure and properties of the PEN films were investigated by using Fourier transform IR spectroscopy, viscometry, microscopy, and tensile tests. The experimental results showed that the coating with silicone enhanced thermal stability up to $200^{\circ}C$, and slightly lowered the tensile strength and elongation of the PEN films. Judging from dimensional stability results the silicone coated PEN films can not be used for higher temperature insulator above $230^{\circ}C$. Serious dimensional contraction of films was obtained during heat treatment at $250^{\circ}C$ even for 1h. However, the surface of those films still have same chemical structure of silicones. Therefore, If we use PEN film prestretched at $230^{\circ}C$ as base one it will be possible to prepare a high temperature insulator up to $230^{\circ}C$. Conclusively, a silicone coated PEN film can be suitable for the application to convection microwave oven door insulator at high temperature up to $230^{\circ}C$.

A Study on the Characterization of Ni-C Thin Films Utilizing a Dual-Source Deposition System (듀얼 소스 증착장치를 이용한 Ni-C 박막의 특성에 관한 연구)

  • Han, Chang-Suk;Chun, Chang-Hwan;Han, Seung-Oh
    • Journal of the Korean Society for Heat Treatment
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    • v.21 no.5
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    • pp.235-243
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    • 2008
  • Ni-C composite films were prepared using a combination of microwave plasma CVD and ion beam sputtering deposition working in a codeposition way. The structure of these films was characterized by energy-dispersive X-ray diffraction (EDXRD), transmission electron microscopy (TEM) and Raman spectroscopy. It was found that a nickel carbide phase, $Ni_3C$ (hcp), formed as very fine crystallites over a wide temperature range when Ni-C films were deposited at low $CH_4$ flow rates. The thermal stability of this nonequilibrium carbide $Ni_3C$ was also studied. As a result, the $Ni_3C$ carbide was found to decompose into nickel and graphite at around $400^{\circ}C$. With high $CH_4$ flow rates (> 0.2 sccm), the structure of the Ni-C films became amorphous. The formation behavior of the carbide and amorphous Ni-C phases are discussed in relation to the electrical resistivity of the films.

Growth Properties of Carbon nanowall according to the Reaction Gas Ratio (반응가스 비율에 따른 탄소나노월의 성장특성)

  • Kim, Sung-Yun;Kang, Hyunil;Choi, Won Seok;Joung, Yeun-Ho;Lim, Yonnsik;Yoo, Youngsik;Hwang, Hyun Suk;Song, Woo-Chang
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.4
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    • pp.351-355
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    • 2014
  • Graphite electrodes are used for secondary batteries, fuel cells, and super capacitors. Research is underway to increased the reaction area of graphite electrodes used carbon nanotube (CNT) and porous carbon. CNT is limited to device utilization in order to used a metal catalyst by lack of surface area to improve. In contrast carbon nanowall (CNW) is chemically very stable. So this paper, microwave plasma enhanced chemical vapor deposition (PECVD) system was used to grow carbon nanowall (CNW) on Si substrate with methane ($CH_4$) and hydrogen ($H_2$) gases. To find the growth properties of CNW according to the reaction gas ratio, we have changed the methane to hydrogen gas ratios (4:1, 2:1, 1:2, and 1:4). The vertical and surficial conditions of the grown CNW according to the gas ratios were characterized by a field emission scanning electron microscopy (FE-SEM) and Raman spectroscopy measurements showed structure variations.

Synthesis of Three-Dimensional Graphene Using Porous Nickel Nanostructure (다공성 니켈 나노 구조체를 이용한 3차원 그래핀의 합성)

  • Song, Wooseok;Myung, Sung;Lee, Sun Sook;Lim, Jongsun;An, Ki-Seok
    • Composites Research
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    • v.29 no.4
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    • pp.151-155
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    • 2016
  • Graphene has been a valuable candidate for use as electrodes for supercapacitors. In order to improve the surface area of graphene, three-dimensional graphene was synthesized on porous Ni nanostructure using thermal chemical vapor deposition and microwave plasma chemical vapor deposition. The structural and chemical characterization of synthesized graphene was performed by scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. It was confirmed that three-dimensional and high-crystalline multilayer graphene onto various substrates was synthesized successfully.

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

  • Shi, Gang;Che, Youxin;Wu, Luyan;Rong, Yao;Ni, Caihua
    • 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.

Microwave Dielectric Properties of Low Temperature Fired (${Pb_{0.45}}{Ca_{0.55}}$) [(${Fe _{0.5}}{Nb_{0.5}}$)$_{0.9}{Sn_{0.1}}$]$O_3$Ceramics with Various Additives

  • Ha, Jong-Yoon;Park, Ji-Won;Yoon, Seok-Jin;Kim, Hyun-Jai;Yoon, Ki-Hyun
    • Journal of the Korean Ceramic Society
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    • v.38 no.7
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    • pp.597-601
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    • 2001
  • The effect of CuO, $B_2$ $O_3$, $V_2$ $O_{5}$ and CuO-B $i_2$ $O_3$additives on microwave dielectric properties of (P $b_{0.45}$C $a_{0.55}$) [(F $e_{0.5}$N $b_{0.5}$)$_{0.9}$S $n_{0.1}$] $O_3$(PCFNS) were investigated. The PCFNS ceramics were sintered at 11$65^{\circ}C$. To decrease the sintering temperature for using as a low-temperature co-firing ceramics (LTCC), CuO, $B_2$ $O_3$, $V_2$ $O_{5}$ and CuO-B $i_2$ $O_3$were added to the PCFNS. As the content of CuO increased, the sintered density and dielectric constant increased and the temperature coefficient of resonance frequency ($\tau$$_{f}$) shifted to the positive value. When the CuO-B $i_2$ $O_3$were added, dielectric properties were $\varepsilon$$_{r}$ of 83, Q. $f_{0}$ of 6085 GHz, and $\tau$$_{f}$ of 8ppm/$^{\circ}C$ at a sintering temperature of 100$0^{\circ}C$. The relationship between the microstructure and properties of ceramics was studied by X-ray diffraction and scanning electron microscopy.icroscopy.y.icroscopy.y.

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Growth Behavior of Aluminum Borate Whisker under 2.45 GHz Electromagnetic Irradiation (2.45 GHz 전자기파 조사하에서 Aluminum Borate Whisker의 성장 거동)

  • 김성완;이상근;김지경;이창희;안진모;신준식;박성수;박희찬
    • Journal of the Korean Ceramic Society
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    • v.40 no.10
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    • pp.998-1004
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    • 2003
  • With starting materials of two different powder mixtures, $Al_2$(S $O_4$)$_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7) and ${\gamma}$-Al$_2$ $O_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7), whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were synthesized by using conventional and microwave heat-treatment. The effects of microwave, amount of flux and temperature on the growth of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were investigated by using X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). With increase of heat-treatment temperature and amount of flux, the size of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles increased in both conventional and microwave heat-treated samples. However, compared to the conventional heat-treated samples, whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were well grown for the microwave heat-treated samples.ted samples.

The Mineralogical and Chemical Characteristics of Fe Impurities and the Efficiency of their Removal Using Microwave Heating and Magnetic Separation in the Pyrophyllite Ore (엽납석광석에 존재하는 Fe 불순물의 광물학적/화학적 특성과 마이크로웨이브 가열 및 자력분리에 의한 제거효과)

  • Cho, Kang-Hee;Kim, Bong-Ju;Choi, Nag-Choul;Park, Cheon-Young
    • Journal of the Mineralogical Society of Korea
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    • v.29 no.2
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    • pp.47-58
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    • 2016
  • The Fe-component of pyrophyllite is an impurity that reduces its grade in the final product. In order to identify the amount of impurity in pyrophyllite and to remove the Fe from the ore using a dry method, microwave heating and magnetic separation were carried out. Pyrite and hematite were identified to contain pyrophyllite by microscopy, XRD, XRF, SEM/EDS and EPMA analysis. It is suggested that the euhedral pyrite in the pyrophyllite is formed by hydrothermal solution, and then the dissolution cavity structure is formed with a partial remainder of the pyrite which dissolved in acidic water. And the $Fe^{3+}$ ion contained in the acidic water precipitated out in the concentric structure of hematite as the origin of sedimentary structure. As a result of the microwave heating and magnetic separation experiments, the Fe removal rates obtained were 96% and 93% from pyrophyllite ore from the Sunsan mine and Wando mine, respectively. It is confirmed that the microwave heating and magnetic separation method was an environmentally friendly method to upgrade the low-grade pyrophyllite.