• Title, Summary, Keyword: Microwave microscopy

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Preparation of Submicron Nickel Powders with Non-aqueous Solvent In Microwave-Assisted Reduction Method (비수계 용매를 사용하는 마이크로파 환원법에 의한 서브마이크론 니켈 분말의 합성)

  • Jeon, Seung Yup;Kim, Jae-Hwan;Park, Na Yi;Park, Hoy Yul;Lee, Gun-Dae;Hong, Seong-Soo;Park, Seong Soo
    • Applied Chemistry for Engineering
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    • v.18 no.4
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    • pp.320-325
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    • 2007
  • Nickel powders were prepared from an aqueous nickel acetate solution and hydrazine hydrate using diethanolamine as the nonaqueous organic solvent in the conventional and microwave synthetic method. It was investigated that microwave non-thermal effect and synthetic condition affect the preparation of nickel powders by means of X-ray diffractometry, scanning electron microscopy, thermal gravymetry analysis, and X-ray photoelectron spectroscopy analysis. Compared with the conventional synthetic method, less of aggregation, smaller particle size, and more uniform distribution of particle size were obtained in the microwave synthetic method due to the non-thermal effect of microwaves.

The effects of mineral salt catalysts on selectivity of phenolic compounds in bio-oil during microwave pyrolysis of peanut shell

  • Mamaeva, Alisa;Tahmasebi, Arash;Yu, Jianglong
    • Korean Journal of Chemical Engineering
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    • v.34 no.3
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    • pp.672-680
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    • 2017
  • Catalytic microwave pyrolysis of peanut shell (PT) using $Fe_3O_4$, $Na_2CO_3$, NaOH, and KOH for production of phenolic-rich bio-oil was investigated. The effects of catalyst type, pyrolysis temperature, and biomass/catalyst ratio on product distribution and composition were studied. Among four catalysts tested, $Na_2CO_3$ significantly increased the selectivity of phenolic compounds in bio-oil during microwave pyrolysis. The highest phenolics concentration of 57.36% (area) was obtained at $500^{\circ}C$ and $PT:Na_2CO_3$ ratio of 8 : 1. The catalytic effect to produce phenolic compounds among all the catalysts tested can be summarized in the order $Na_2CO_3$>$Fe_3O_4$>KOH>NaOH. Using KOH and NaOH as catalyst resulted in formation of bio-oil with enhanced higher heating value (HHV) and lower oxygen content, indicating that these catalysts enhanced the deoxygenation of bio-oil. The scanning-electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis of char particles showed the melting of magnetite and vaporization-condensation of mineral salt catalysts on char particle, which was attributed to extremely high local temperatures during microwave heating.

Microwave Dielectric Properties of Ferroelectric PZT Thin Films (PZT 강유전체 박막의 마이크로파 유전특성)

  • Kwak, Min-Hwan;Moon, Seong-Eon;Ryu, Han-Cheol;Kim, Young-Tae;Lee, Sang-Seok;Lee, Su-Jae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.719-722
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    • 2003
  • Ferroelectric $Pb(Zr_{1-x}Ti_x)O_3$ (PZT) films were deposited on (001) MgO single crystals using sol-gel method. Structural properties and surface morphologies of PZT films were investigated using an X-ray diffractometer and a scanning electron microscopy, respectively. The dielectric properties of PZT films were investigated with the dc bias field using interdigitated capacitors (IDC) which were fabricated on PZT films using a thick metal layer by photolithography and dry etching process. The small signal dielectric properties of PZT films were calculated by a modified conformal mapping method with low and high frequency data, such as capacitance measured by an impedance gain/phase analyzer at 100 kHz and reflection coefficient (S-parameter) measured by a HP 8510C vector network analyzer at 1 -20 GHz. The IDC on PZT films exhibited about 67% of capacitance change with an electric field of 135 kV/cm at 10 GHz. These PZT thin films can be applied to tunable microwave devices such as phase shifters, tunable resonators and tunable filters.

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Conductivity changes of copper(II)-phthalocyanie thin films due to annealing time of grain growing measuring microwave reflection coefficients (마이크로파 반사계수 측정을 통한 Copper(II)-phthalocyanine 박말의 결정 성장 시간에 따른 전기전도도 특성 변화 연구)

  • Park, Mie-Hwa;Yoo, Hyun-Jun;Lim, Eun-Ju;Na, Seung-Wook;Lee, Kie-Jin;Cha, Deok-Joon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.1074-1078
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    • 2004
  • 열 중착 방법을 이용하여 copper(II)-phthalocyanine(CuPc) 박막을 glass 기판 위에 제작하였다. 박막은 열처리를 하지 않은 경우와 열처리 조건을 $150^{\circ}C$ 로 후열(annealing) 처리 하는 방식으로 하였으며 후열 처리한 경우 $150^{\circ}C$에서의 열처리 지속 시간을 각각 2시간, 3시간, 4시간으로 달리하였다. 제작된 박막의 전기전도도를 평가하기 위해 마이크로파의 근접장 효과를 이용한 근접장 현미경(near-field scanning microwave microscope)을 이용하여 비파괴적인 방식으로 CuPc 박막의 반사계수(reflection coefficient)를 측정하였다. CuPc 박막의 전기전도도 특성을 UV 흡수도를 통한 HOMO(highest occupied molecular orbital), LUMO(lowest unoccupied molecular orbital) 준위의 밴드갭의 shift 현상과 관련지어 설명하였다. 박막 표면 특성은 SEM(scanning microscope microscopy)을 통해 관측하였다. 열처리 지속 시간에 따른 CuPc 박막의 전기전도도 특성은 2시간으로 지속한 경우의 박막의 경우 가장 좋았으며 그 보다 더 오랜 시간 동안 열처리를 지속한 경우에는 전기 전도 특성이 오히려 나빠짐을 알 수 있었다.

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Manufacture of Titania-silica Composite Anode Materials by Sol-gel Method (졸-겔법을 이용한 Titania-silica 혼합 음극활물질의 제조)

  • Bang, Jong-Min;Cho, Young-Im;Na, Byung-Ki
    • Clean Technology
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    • v.16 no.2
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    • pp.140-144
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    • 2010
  • Titania-silica composite materials were obtained by sol-gel method from TiCl4 and TEOS precusors, and they were applied to anode materials of lithium ion battery. Uniformly distributed composite materials can be manufactured by sol-gel method. The composite materials were heat treated by microwave to obtain materials with new properties. The experimental variables were composition of the material, heat treatment temperature, and microwave exposure. The structure and surface properties of the materials were analyzed by XRD, SEM, and the electrochemical capacity was measured with charge/discharge cycler.

Evolution pathway of CZTSe nanoparticles synthesized by microwave-assisted chemical synthesis

  • Reyes, Odin;Sanchez, Monica F.;Pal, Mou;Llorca, Jordi;Sebastian, P.J.
    • Advances in nano research
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    • v.5 no.3
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    • pp.203-214
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    • 2017
  • In this study we present the reaction mechanism of $Cu_2ZnSnSe_4$ (CZTSe) nanoparticles synthesized by microwave-assisted chemical synthesis. We performed reactions every 10 minutes in order to identify different phases during quaternary CZTSe formation. The powder samples were analyzed by x-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that in the first minutes copper phases are predominant, then copper and tin secondary phases react to form ternary phase. The quaternary phase is formed at 50 minutes while ternary and secondary phases are consumed. At 60 minutes pure quaternary CZTSe phase is present. After 60 minutes the quaternary phase decomposes in the previous ternary and secondary phases, which indicates that 60 minutes is ideal reaction time. The EDS analysis of pure quaternary nanocrystals (CZTSe) showed stoichiometric relations similar to the reported research in the literature, which falls in the range of Cu/(Zn+Sn): 0.8-1.0, Zn/Sn: 1.0-1.20. In conclusion, the evolution pathway of CZTSe synthesized by this novel method is similar to other synthesis methods reported before. Nanoparticles synthesized in this study present desirable properties in order to use them in solar cell and photoelectrochemical cell applications.

The Effects of CF4 Partial Pressure on the Hydrophobic Thin Film Formation on Carbon Steel by Surface Treatment and Coating Method with Linear Microwave Ar/CH4/CF4 Plasma

  • Han, Moon-Ki;Cha, Ju-Hong;Lee, Ho-Jun;Chang, Cheol Jong;Jeon, Chang Yeop
    • Journal of Electrical Engineering and Technology
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    • v.12 no.5
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    • pp.2007-2013
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    • 2017
  • In order to give hydrophobic surface properties on carbon steel, the fluorinated amorphous carbon films were prepared by using linear 2.45GHz microwave PECVD device. Two different process approaches have been tested. One is direct deposition of a-C:H:F films using admixture of $Ar/CH_4/CF_4$ working gases and the other is surface treatment using $CF_4$ plasma after deposition of a-C:H film with $Ar/CH_4$ binary gas system. $Ar/CF_4$ plasma treated surface with high $CF_4$ gas ratio shows best hydrophobicity and durability of hydrophobicity. Nanometer scale surface roughness seems one of the most important factors for hydrophobicity within our experimental conditions. The properties of a-C:H:F films and $CF_4$ plasma treated a-C:H films were investigated in terms of surface roughness, hardness, microstructure, chemical bonding, atomic bonding structure between carbon and fluorine, adhesion and water contact angle by using atomic force microscopy (AFM), nano-indentation, Raman analysis and X-ray photoelectron spectroscopy (XPS).

Deposition of c-BN Films on Tungsten Carbide Insert Tool by Microwave Plasma Enhanced Chemical Vapor Deposition(MPECVD) (MPECVD법에 의한 초경인서트 공구의 c-BN 박막 증착)

  • Yoon, Su-Jong;Kim, Tae-Gyu
    • Journal of the Korean institute of surface engineering
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    • v.41 no.2
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    • pp.43-47
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    • 2008
  • Cubic boron nitride(c-BN) films were deposited on tungsten carbide insert tool by microwave plasma enhanced chemical vapor deposition(MPECVD) from a gas mixture of triethyl borate$(B(C_2H_5O)_3)$, ammonia $(NH_3)$, hydrogen$(H_2)$ and argon(Ar). The qualities of deposited thin film were investigated by x-ray diffrac-tion(XRD), field emission scanning electron microscopy(FE-SEM) and micro Raman spectroscope. The surface morphologies of the synthesised BN as well as crystallinity appear to be highly dependent on the flow rate of $B(C_2H_5O)_3$ and $(NH_3)$ gases. The deposited film had more crystallized phases with 5 scem of $B(C_2H_5O)_3$ and $(NH_3)$ gases than with 2 sccm, and the phase was identified as c-BN by micro Raman spectroscope and XRD. The adhesion strength were also increased with increasing flow rates of $B(C_2H_5O)_3$ and $(NH_3)$ gases.

A Study on the Diamond Synthesis by MPECVD using $CO-H_2$ Mixture ($CO-H_2$ 혼합 기체의 MPECVD 에 의한 다이아몬드 합성에 관한 연구)

  • Ku, Ja-Chun;Oh, Jeong-Seob;Hwang, Ki-Woong
    • Proceedings of the KIEE Conference
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    • pp.390-393
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    • 1989
  • Diamond is synthesized from the gaseous mixture of carbon monoxide and hydrogen by microwave PECVD. $10{\times}10mm^2$ silicon wafers are used as the substrate,and it can be raised more than $900^{\circ}C$ by microwave absorption, radiation by plasma and bombardment of ions. The changes of the morphology and the growth rates of the deposits with the experimental conditions are examined by Scanning Electron Microscopy. The d values of all the deposited films concide with those of powder diffraction data in XRD. In Raman spectra, the peak of the deposit coincides with that of the natural diamond which has a value of 1332.5 $cm^{-1}$, and the broad peak from 1360 $cm^{-1}$to 1600 $cm^{-1}$which represents the amorphous graphite was observed in the higher concentration of carbon monoxide.

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The Study on Growls of diamond thin films Synthesized by Microwave Plasma Enhanced Chemical Vapor Deposition (Microwave Plasma CVD에 의한 Diamond 박막의 성장)

  • 이병수;이상희;박구범;박종관;박상현;유도현;이덕출
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.373-376
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    • 1997
  • Diamond thin films were deposited on P-type(100) Si wafers using MPECVD. Prior to deposition, mechanical scretching was done to improve density of nucleation sites with diamond paste of 0.25${\mu}{\textrm}{m}$ size. Diamond films were deposited under the following conditions : methane concentration of 0.5~5%, oxygen concentration of 0~70%, process pressure of 70Torr, process temperature of 900~95$0^{\circ}C$, and deposition time 5hrs. The changes of the morphology and the growth rates of the deposits with the experimental conditions are expriend by Scanning Electron Microscopy. Raman Spectroscopy and X-ray Diffraction method.

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