• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1981-1987
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• 2010

A novel composite (Ag-CNT/$TiO_2$) of silver treated carbon nanotubes (Ag-CNT) and $TiO_2$ was synthesized via wet chemistry followed by a heat treatment. The dispersion and structure of the silver in the synthesized composites determined by X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy(TEM). XRD patterns of the composites showed that the composites contained a mixing anatase and rutile phase. The EDX spectra showed the presence of C, O, Ti and Ag peaks. The $TiO_2$ particles were distributed uniformly in the CNT network, and silver particles were virtually fixed on the surface of the tube. The photocatalysis degraded behaviors of the Ag-CNT/$TiO_2$ composites of the methylene blue, which increased with an increase of the silver component. The Ag-CNT/$TiO_2$ composites have excellent antibacterial activities against Escherichia coli (E. Coli), Pseudomonas aeruginosa (P. Aeru) and Bacillus subtilis (B. Sub) under visible light.

• 대한화학회지
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• 제61권4호
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• pp.168-178
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• 2017

$La/TiO_2$ - graphene composites were synthesized in this study, and applied to the photocatalytic degradation of Rhodamine B (RhB) under UV-visible light irradiation. X-ray diffraction (XRD), surface analysis, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) analysis demonstrated that $La/TiO_2$ nanoparticles were well distributed on the surface of graphene, and formed the heterostructure of $La/TiO_2$-graphene. Compared to the pure $TiO_2$, $La/TiO_2$-graphene composites displayed much higher photocatalytic activities in RhB degradation under UV-visible light irradiation. The photocatalytic data of $La/TiO_2$-graphene composites exhibit extended light absorption in the visible light region, and possess better charge separation capability than that of pure $TiO_2$. The high photocatalytic activity was attributed to the composite's high adsorptivity, extended light absorption, and increased charge separation efficiency, due to the excellent electrical properties of graphene, and the large surface contact between graphene and $La/TiO_2$ nanoparticles.

• 한국세라믹학회지
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• 제55권6호
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• pp.581-589
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• 2018

This work concentrated on the effect of different laser beams on the microstructure and dielectric properties of $BaTiO_3$ nanoparticles at different calcinations times during the gelling preparation step. The nanoparticles were prepared by the sol-gel method. A green (1000 mW, 532 nm) and red laser beam (500 mW, 808 nm), were applied vertically at the center of stirring raw materials. The samples were sintered at $1000^{\circ}C$ for 2, 4, and 6 h. X-ray diffraction (XRD) analysis showed that samples prepared under the green laser have the highest purity. The FT-IR spectra showed that the stretching and bending vibrations of TiO bond without any other bonds, which are compatible to the X-ray diffraction (XRD) results. Samples were characterized by transmission electron microscopy (TEM), Scan electron microscopy (SEM), and UV-Visible spectrophotometer. Characterization showed the samples prepared under the green laser to have the highest particle size (~ 50 nm) and transparency for all sintering durations. Laser beam effects on electrical characterization were studied. BT nanoparticles prepared under the green laser show the higher dielectric constant, which was found to increase with sintering temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.49-49
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• 2009

Nanocomposites of gold nanoparticles and multi-walled carbon nanotubes (MWNTs) were prepared by electrostatic interaction. Gold nanopartic1es were stabilized by polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS) and poly(sodium-4-styrenesulfonate) (PSS) in aqueous medium, and MWNTs were modified by poly(diallyldimethylammonium)chloride (PDDA) in water. The as-perpared Au-MWNT nanocomposites were structurally and electrically characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV/Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and cyclo voltammetry (CV). UV/Vis spectra of Au-MWNT nanocomposites showed the characteristic surface plasmon bands in the range of ~515nm, depending on the stabilizers. There is only slight change on the band shape with variation of stabilizing agents for gold nanoparticles. Through FE-SEM and TEM images, the distribution of gold, nanoparticles on the sidewalls of MWNTs was deliberately investigated on Au-MWNT nanocomposites treated with different stabilizers. XPS and CV showed redistribution of electron densities and changes in the binding energy states of nanopartic1es in nanocomposite respectively.

• 한국표면공학회지
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• 제33권2호
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• pp.126-134
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• 2000

This study investigated the bath compositions and plating conditions and crystal structure used for achieving nickel-thallium-phosphorus deposits by means electroless plating. The electroless nickel-thallium-phosphorus deposits were achieved with a bath using sodium hypophosphite as the reducing agent and sodium citrate as the complexing agent. The depositing rate was 10.5mg.$cm^{2-1}$ .$hr^{-1 }$ from the optimistic bath composition, 0.1M nickel sulfate, 0.005M thallium sulfate, 0.2M sodium hypophosphite, and 0.05M sodium citrat and the recommended plating conditions, pH 5.5 and $90^{\circ}C$. The composition of alloy deposits determined by X-ray analysis (EDS) that the Thallium was increased with major increasing concentration of complexing agent and thallium ion in bath solution, it decreased according to the increasing concentrations of reduction agent in the bath solution, Bit Phosphorus showed a contrary to the thallium. It was observed from X-ray diffraction analysis, Scanning Electron Microscopy and Transmission Electron Microscopy. The crystalline structure of deposits was amorphous at the first deposited state but it was changed $Ni-T1-Ni_{5}$ $P_2$ polycrystalline when subjected to 1 hour heat treatment of more than $350^{\circ}C$. TEM observation demonstrated that the microstructure was identical to the result of the XRD at as deposited but it became $Ni-Tl-Ni_{5}$ $P_2$ polycrystalline when heated. And grain size was 10-50nm.

• 전기화학회지
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• 제15권2호
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• pp.90-94
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• 2012

We report nanostructure electrodes with $TiO_2$ as a core and carbon as a shell ($TiO_2$@C) for oxygen reduction in alkaline solution. The structure of core-shell electrodes is characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction method, and X-ray photoelectron microscopy. The electrochemical properties of the $TiO_2$@C electrodes are characterized using a potentiostat and compared with those of carbon supported Pt catalyst. In particular, the core-shell electrode with dominant pyridinic-N component exhibits an imporved electrocatalytic activity for oxygen reduction reaction in alkaline solution.

• 한국결정성장학회지
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• 제23권1호
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• pp.27-30
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• 2013

Catalyst-free graphene nano-sheets without substrates have been synthesized using fullerene and a high direct current (dc) pulse in the spark plasma sintering (SPS) process. Graphene nano-sheets were synthesized directly in the gas phase of carbon atoms which are generated from fullerene at a temperature of $600^{\circ}C$. Characterization has been carried out by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD).

• Journal of Magnetics
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• 제17권2호
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• pp.96-99
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• 2012

The change of saturation magnetization in boronized low carbon microalloyed steels was investigated as a function of boronizing time. Specimens were boronized in an electrical resistance furnace for times ranging from 3 to 9 h at 1123 K. The metallurgical and magnetic properties of the specimens were investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). A boride layer with saw-tooth morphology consisting of FeB and $Fe_2B$ was observed on the surface, its thickness ranged from 63 ${\mu}m$ to 140 ${\mu}m$ depending on the boronizing time. XRD confirmed the presence of $Fe_2B$ and FeB on the surface. The saturation magnetization decreased with increasing boronizing time. This decrease was attributed to the increased thickness of the FeB and $Fe_2B$ phases. Cracks were observed at the FeB/$Fe_2B$ interfaces of the samples. The number of interfacial cracks increased with increasing boronizing time.

• International Journal of Concrete Structures and Materials
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• 제10권1호
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• pp.113-124
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• 2016

This paper presents the effect of silica fume and nano silica, used individually and in combination with the set accelerator and/or hydrated lime, on the properties of class F high volume ultra fine fly ash (HV-UFFA) cement composites, replacing 80 % of cement (OPC). Compressive strength test along with thermogravimetric analysis, X-ray diffraction and scanning electron microscopy were undertaken to study the effect of various elements on the physico-chemical behaviour of the blended composites. The results show that silica fume when used in combination with the set accelerator and hydrated lime in HV-UFFA cement mortar, improves its 7 and 28 day strength by 273 and 413 %, respectively, compared to the binary blended cement fly ash mortar. On the contrary, when nano silica is used in combination with set accelerator and hydrated lime in HV-UFFA cement mortar, the disjoining pressure in conjunction with the self-desiccation effect induces high early age micro cracking, resulting in hindering the development of compressive strength. However, when nano silica is used without the additives, it improves the 7 and 28 day strengths of HV-UFFA cement mortar by 918 and 567 %, respectively and the compressive strengths are comparable to that of OPC.

• 한국세라믹학회지
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• 제18권4호
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• pp.219-228
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• 1981

To clarify influences of silicious raw materials on mineralogcal and petrological properties in clinkering process clay, shale, quartzite, sand and coal ash have been used as silicious raw materials. The tests on thermal properties, reactivity and burnability of raw mixtures which have different silicious raw materials respectively have been made by means of X-ray diffractometry, differential thermal analysis, optical microscopy and transmission electron microscopy. Limestone contains coarse crystalline grains which show 0.1-1.0mm and its decarbonation temperature is 86$0^{\circ}C$. Reaction temperatures among raw mixtures have been determined by X-ray diffractometry and their results are as follows; clay minerals under 1, 00$0^{\circ}C$, mica group, 100$0^{\circ}C$-110$0^{\circ}C$, feldspar group, 1, 10$0^{\circ}C$-1, 20$0^{\circ}C$ and quartz 1, 20$0^{\circ}C$-1, 30$0^{\circ}C$. Burnabilities of raw mixtures of different temperatures have been found that they mainly depend upon their mineral contents in silicious raw materials and their order is as follows; $clay\geq shale\gg quartzite \geq sand$.