• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.151-154
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• 1998

The layered trivanadate, LiV$_3$O$_{8}$ has been investigated as a cathode material for secondary lithium batteries. Early in its development the preparation method of LiV$_3$O$_{8}$ strongly influenced its electrochemical properties, such as discharge capacity, rate capability and cycling efficiency. In the present experiment, a new synthesis route has been applied to obtain LiV$_3$O$_{8}$ . Instead of the conventional high temperature technique leading to the crystalline form, a solution technique producing the amorphous form has been used. This material, after dehydration, shows an electrochemical performance exeeding that of the crystalline one. The rationale for this behavior mainly lies in microscopic factors, i.e., in the possibility for the unit cell of amorphous LiV$_3$O$_{8}$ to insert up to 9 Li$^{+}$, instead of six for crystalline LiV$_3$O$_{8}$ . The ultrasonically treated products in water were characterized by XRD, TGA, DSC, and SEM. These measurements showed that the ultrasonic treatment process of crystalline LiV$_3$O$_{8}$ causes a decrease in crystallinity and considerable increases in specific surface area and interlayer spacing.g.

• 한국전기전자재료학회논문지
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• 제19권5호
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• pp.432-436
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• 2006

The $ZnGa_2O_4$ and Mn, Cr-doped $ZnGa_2O_4$ Phosphors were synthesized through conventional solid state reactions. The XRD patterns show that the $ZnGa_2O_4$ has a (3 1 1) main peak and a spinel phase. The emission wavelength of $ZnGa_2O_4$ showed main peak of 420 nm and maximum intensity at the sintering temperature of $1100^{\circ}C$. In the crystalline $ZnGa_2O_4$, the Mn shows green emission (510 nm, $^4T_1-^6A_1$) with a quenching concentration of 0.6 mol%, and the Cr shows red emission (705 nm, $^4T_2-^4A_2$) with a quenching concentration of 2 mol%. These results indicate that $ZnGa_2O_4$ Phosphors hold promise for potential applications in field emission display devices with high brightness operating in full color regions.

• Membrane and Water Treatment
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• 제6권3호
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• pp.251-262
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• 2015

In this work the preparation and characterization of a membrane containing a uniform mesoporous Titanium oxide top layer on a porous stainless steel substrate has been studied. The 316 L stainless steel substrate was prepared by powder metallurgy technique and modified by soaking-rolling and fast drying method. The mesoporous titania membrane was fabricated via the sol-gel method. Morphological studies were performed on both supported and unsupported membranes using scanning electron microscope (SEM) and field emission scanning microscope (FESEM). The membranes were also characterized using X-ray diffraction (XRD) and $N_2$-adsorption / desorption measurement (BET analyses). It was revealed that a defect-free anatase membrane with a thickness of $1.6{\mu}m$ and 4.3 nm average pore size can be produced. In order to evaluate the performance of the supported membrane, single-gas permeation experiments were carried out at room temperature with nitrogen gas. The permeability coefficient of the fabricated membrane was $4{\times}10^{-8}\;lit\;s^{-1}\;Pa^{-1}\;cm^{-1}$.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1949-1954
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• 2012

We have developed a novel and eco-friendly synthetic route for the preparation of a two-dimensional layered zinc hydroxide with intercalated nitrate anions. The layered zinc hydroxide nitrate, called 'zinc basic salt', was, in general, successfully synthesized, using an electron beam irradiation technique. The 2-propanol solutions containing hydrated zinc nitrate were directly irradiated with an electron-beam at room temperature, under atmospheric conditions, without stabilizers or base molecules. Under electron beam irradiation, the reactive OH radicals were generated by radiolysis of water molecules in precursor metal salts. After further radiolytic processes, the hydroxyl anions might be formed by the reaction of solvated electrons and the OH radical. Finally, the $Zn_5(OH)_8(NO_3)_2{\cdot}2H_2O$ was precipitated by the reaction of zinc cation and hydroxyl anions. Structure and morphology of obtained compounds were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). The chemical components of the products were determined by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA). The thermal behavior of products was studied by thermogravimetric (TG) and differential thermal analysis (DTA).

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3679-3683
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• 2010

Niobium oxide ($Nb_2O_5$) and phosphated $Nb_2O_5$ were synthesized and used as catalysts for sorbitol dehydration to isosorbide. The characterization results of $N_2$ adsorption, XRD and $NH_3$-TPD revealed that the phosphoric acid modification could well prevent the crystallization of $Nb_2O_5$. And the amorphous phosphated $Nb_2O_5$ catalysts kept the relatively large surface area and stable acidity at high calcination temperature. The catalytic results showed that the selectivity to isosorbide could be dramatically enhanced over phosphated $Nb_2O_5$. The excellent catalytic performance with 100.0% sorbitol conversion and 62.5% isosorbide selectivity were obtained over the 0.8P/NBO-400 catalyst. Comparing with $Nb_2O_5$ catalysts, phosphated $Nb_2O_5$ catalysts regenerated through a simple calcination process showed no significant activity loss after recycling three runs.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.373-376
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• 2010

아산화질소를 추진제로 사용하기 위해 아산화질소의 촉매 분해 특성과 고온 하에서 내열성을 연구하였다. 기존의 Ru 촉매의 내열성을 개선하기 위해 추가적으로 $Al_2O_3$ 지지체에 Si를 담지시킨 후 Ru을 담지하였다. 관형 반응기를 이용하여 반응온도에 따른 아산화질소의 전환율을 측정하고, Si 첨가에 의한 분해특성에 대해서 연구하였다. 반응온도가 높을수록 전환율이 우수했고, Ru/$Al_2O_3$-Si 촉매가 Ru/$Al_2O_3$ 촉매보다 높은 전환율을 보였다.

• 한국세라믹학회지
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• 제52권2호
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• pp.114-118
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• 2015

$V_2O_5-P_2O_5-ZnO-Sb_2O_3$ glasses modified with BaO and $Al_2O_3$ are synthesized as a sealing material for large-scale dye-sensitized solar cells (DSSCs). A compositional study is performed in order to determine the glass that can be sintered below $500^{\circ}C$ with a high chemical stability against the electrolyte. The flow size of the glasses after the heat treatment and the glass stability are increased with the addition of $Al_2O_3$ and BaO, while the glass transition temperature is decreased. After the reaction with the electrolyte at $60^{\circ}C$ for 72 h, the addition of 5 mol% of BaO and 2 mol% of $Al_2O_3$ considerably enhances the chemical stability of the glass. X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to examine the reaction between the electrolyte and glasses. The structural contribution of the additives is also investigated and discussed.

• 한국안전학회지
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• 제27권6호
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• pp.59-63
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• 2012

The use of dry chemical powder has been increased as it can be stored for a long period and sustain in stable condition compared to gas or liquid phase extinguishing agents. A new type of dry chemical powder using Zeolite was produced in the research. Chemical powder was adsorbed into Zeolite 13X, a porous material appearing negative catalytic effect, to create extinguishing powder obtaining core shell structure and measured physical properties and run a small scale fire extinguishment. SEM, XRD, TA analysis was also executed, and extinguishing characteristics were measured by fire extinguishing experiment on oil pool fire. The experiment showed that the average particle size of Zeolite 13X was equivalent, indicating about $3{\pm}1{\mu}m$ and thermal analysis result illustrated that Zeolite 13X showed exothermic reaction peaks at $900^{\circ}C$ due to solid-state transformation. Extinguishing characteristics on oil fire of $NaHCO_3$/Zeolite 13X and $NH_4H_2PO_4$/Zeolite were improved, influenced by adsorbed extinguishing powders on Zeolite 13X and Zeolite 13X that contains high phase transition temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.60-61
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• 2007

IAZO (indium aluminium zinc oxide) anode films were co-sputtered on glass substrate using a dual target DC magnetron sputtering system. For preparation of IATO films, at constant DC power of IZO (indium zinc oxide) target of 100 W, the DC power of AZO (Aluminum zinc oxide) target was varied from 0 to 100 W. To analyze electrical and optical properties of IAZO anode, Hall measurement examination and UV/V is spectrometer were performed, respectively. In addition, structure of IAZO anode film was examined by X-ray diffraction (XRD) method. Surface smoothness was investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). From co-sputtered IAZO anode, good conductivity($2.32{\times}10^{-4}{\Omega}.cm$) and high transparency(approximately 80%) in the visible range were obtained even at low temperature deposition. Finally, J-V-L characteristics of phosphorescent OLED with IAZO anode were studied by Keithley 2400 and compared with phosphorescent OLED with conventional ITO anode.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.175-176
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• 2007

This paper describes on the characteristics of Pd thin films deposited on poly-crystalline 3C-SiC buffer layers for microsensors, in which the poly 3C-SiC was grown on Si, $SiO_2$, and AlN substrates, respectively, by APCVD using HMDS, $H_2$, and Ar gas at $1100^{\circ}C$ for 30 min. In this work, a Pd thin film was deposited on the poly 3C-SiC film by RF magnetron sputter. The thickness, uniformity, and quality of these samples were evaluated by SEM. Crystallinity and orientation of the Pd film were analyzed by XRD. Finally, Pd/poly 3C-SiC schottky diodes were fabricated and characterized by current-voltage measurements. From these results, Pd/poly 3C-SiC devices are promising for high temperature hydrogen sensors and other microsensors.