• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2155-2158
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• 2014

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.735-738
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• 2003

Downsizing electronics requires precision position control with an accuracy of sub-micron order, which demands development of ultra-fine displacive devices. Piezoelectric transducer is one of devices transferring electric field energy into mechanical energy and being capable for fine displacement control. The transducer has been widely used as fine Position control device Multilayer piezoelectric actuator, one of typical piezo-transducer, is fabricated by stacking alternatively ceramic and electrode layers several hundred times followed by cofiring process. Electrode material should be tolerable in the firing process maintaining at ceramic-sintering temperatures up to $1100{\sim}1300^{\circ}C$. Ag-Pd can be used as stable electrode material in heat treatment above $960^{\circ}C$. Besides, adding small quantity ceramic powder allow the actuator to be fabricated in a good shape by diminishing shrinkage difference between ceramic and electrode layers, resulting in avoidance of crack and delamination at and/or nearby interface between ceramic an electrode layers. This study presents synthesis of nano-oxide-added Ag/Pd powders and its feasibility to candidate material tolerable at high temperature. The powders were formed in a co-precipitation process of Ag and Pd in nano-oxide-dispersed solution where Ag and Pd precursors are melted in $HNO_3$ acid.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.222-227
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• 2017

Flake-type micro hollow silica was synthesized by precipitation method using an $Mg(OH)_2$ inorganic template and sodium silicate and ammonium sulfate as the silica precursors. We investigated the effects of the silica precursor concentration on the shape, shell thickness, and surface of the hollow silica. When the concentration of the silica precursor was 0.5 M, the hollow silica had a smooth and translucent thin shell, but the shell was broken. On the other hand, the shell thickness of the hollow silica changed in the range of 12 nm to 18 nm with the increase of the precursor concentration from 0.7 M to 1.1 M. Simultaneously, unintended spherical silica satellites were created on the shell surface. The number of satellites and the size rose according to the increased concentration of silica precursor. The reason for the formation of spherical silica satellites is that the $NH_4OH$ nucleus generated in the synthesis of hollow silica acted as another silica reaction site.

• Journal of Powder Materials
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• v.25 no.2
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• pp.120-125
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• 2018

Boron nitride nanotubes (BNNTs) are receiving great attention because of their unusual material properties, such as high thermal conductivity, mechanical strength, and electrical resistance. However, high-throughput and high-efficiency synthesis of BNNTs has been hindered due to the high boiling point of boron (${\sim}4000^{\circ}C$) and weak interaction between boron and nitrogen. Although, hydrogen-catalyzed plasma synthesis has shown potential for scalable synthesis of BNNTs, the direct use of $H_2$ gas as a precursor material is not strongly recommended, as it is extremely flammable. In the present study, BNNTs have been synthesized using radio-frequency inductively coupled thermal plasma (RF-ITP) catalyzed by solid-state ammonium chloride ($NH_4Cl$), a safe catalyst materials for BNNT synthesis. Similar to BNNTs synthesized from h-BN (hexagonal boron nitride) + $H_2$, successful fabrication of BNNTs synthesized from $h-BN+NH_4Cl$ is confirmed by their sheet-like properties, FE-SEM images, and XRD analysis. In addition, improved dispersion properties in aqueous solution are found in BNNTs synthesized from $h-BN+NH_4Cl$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.392-397
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• 2018

In this paper, the ZnS nanoparticles were synthesized according to the process conditions of hydrothermal synthesis. When the molar ratio of Zn to S was 1:1.2, it was confirmed that it had a cubic single phase and a high crystal phase. After the molar ratio is fixed, hydrothermal synthesis was conducted at $180^{\circ}C$ for 24, 36, 72 and 96 h in order to confirm the structural change with the change of hydrothermal synthesis times. As the hydrothermal synthesis times increased, the particle size increased. The hydrothermal synthesized particle size for 72 h was considered to be suitable for sintering. The ZnS ceramic had a density of 99.7% and an excellent transmittance of ~70% in the long-wavelength region.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.121.2-121.2
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• 2014

Synthesis of catecholamine from aniline is achieved by plasma enhanced CVD process. Catecholamine has a variety of functions in body such as brain and bloodstream controls. Catecholamine also has an interesting property of a material independent ability of functionalizing surface, which is found at mussels' adhesive nature. Synthesis of catecholamine has only been available from DOPA by chemical reduction and oxidation. This study presents the direct synthesis of catecholamine from further elemental source, aniline, which has not been achieved by a conventional chemical method. The process also indicates that a variety of catecholamine can be formed by controlling reactant gases. In additional to PECVD's very useful properties such as conformal, ultrathin and uniform coatings, a direct synthesis from aniline and a capability of controlling formation of a variety catecholamine is believed to open up a numerous applications.

• Journal of Powder Materials
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• v.14 no.3 s.62
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• pp.180-184
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• 2007

The material design and synthesis are of important to modem science and technology. Here, we report the synthesis of multifunctional nanomaterials with different properties: feroelecties $YMnO_3$ and multiferroic materials such as $CoFe_2O_4-YMnO_3,\;Fe_3O_4-YMnO_3,\;CoFe_2O_4-Cd_{0.85}Zn_{0.15}S,\;and\;Fe_3O_4-Cd_{0.85}Zn_{0.15}S$ nano-composites by using a chemical synthesis process. These results provide a simple and convenient synthesis process to produce multifunctional nanocomposites.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2256-2260
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• 2013

A new quinoline-based acylhydrazone (1) has been synthesized and applied as a fluorescent probe. Probe 1 exhibits high selectivity and sensitivity to $Cu^{2+}$ with fluorescence "ON-OFF" behavior in HEPES buffered (1‰ DMSO, HEPES 20 mM, pH = 7.4) solution. The on-site generated 1-$Cu^{2+}$ complex displays excellent selectivity to sulfide ions with fluorescence "OFF-ON" performance through copper displacement approach.

• Metals and materials international
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• v.24 no.6
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• pp.1327-1332
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• 2018

In this study, a novel approach to the explosive synthesis of titanium carbide (TiC) is discussed. Nonstoichiometric $TiC_x$ powder was produced via the underwater explosion of a Ti powder encapsulated within a spherical explosive charge. The explosion process, bubble formation, and synthesis process were visualized using high-speed camera imaging. It was concluded that synthesis occurred within the detonation gas during the first expansion/contraction cycle of the bubble, which was accompanied by a strong emission of light. The recovered powders were studied using scanning electron microscopy and X-ray diffraction. Submicron particles were generated during the explosion. An increase in the carbon content of the starting powder resulted in an increase in the carbon content of the final product. No oxide byproducts were observed within the recovered powders.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.179-179
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• 2016

A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.