• Bulletin of the Korean Chemical Society
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• 제21권3호
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• pp.295-299
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• 2000

The photoluminescence and cathodoluminescence of $SrGa_2S_4:EU$ phosphor were optimized with the process and chemical variables (activators, fluxes and reaction temperature) used in solid state reaction. Firing the powder with flux at $800^{\circ}C$ for 2hr gave the highest photoluminescence efficiency under near-UV excitation and the highest cathodoluminescence efficiency of 20.1 lm/W at 2 kV and 33.3 lm/W at 10 kV. The suitability of $SrGa_2S_4:EU$ for application as a phosphor in LCDs and FEDs is discussed.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 첨단 분리막 연구동향
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• pp.13-35
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• 2004

Metal Complexes in Macromolecules Applications of Polymer Electrolyte Membranes Facilitated Transport in Solid State Roles of Electrolytes in Solar Cells - Electrolytes :ㆍI- and $I_3$-conductor ㆍelectron barrier or hole conductor ㆍelectrochemical redox reaction media ㆍinterfacial contactor for dye, $TiO_2$ and electrode ㆍmechanical separator (omitted)

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1231-1231
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• 2006

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2017년도 임시총회 및 하계학술연구발표회
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• pp.210-210
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• 2017

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.349-350
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• 2002

The friction and wear behaviors of fluorine-containing compounds such as perfluoropolyethers (PFPE), phosphazenes (X-1P), ionic liquids as lubricants for steel/seel, steel/ceramic, ceramic/ceramic were investigated using a SRV tester and a one-way reciprocating friction tester both in ball-on-disc configuration. It was found that the three fluorine-containing lubricants could reduce friction coefficient and wear volume effectively. The effectiveness of the three lubricants in reducing wear volume could be ranked as ionic liquids>X-1P>PFPE. Tests also showed that aryloxyphosphazene with polar substituent as a lubricant of steel/steel pair gave low wear, while aryloxyphosphazene with nonpolar group on the phenyl pendant led to high wear. The morphology and the tribo-chemical reaction of the worn surfaces were analyzed with a scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). XPS analyses illustrated the formation of iron fluoride in steel/steel system with the lubrication of both phosphazenes and ionic liquids.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.411-420
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• 2020

Undesirable interfacial reactions between the cathode and sulfide electrolyte deteriorate the electrochemical performance of all-solid-state cells based on sulfides, presenting a major challenge. Surface modification of cathodes using stable materials has been used as a method for reducing interfacial reactions. In this work, a precursor-based surface modification method using Zr and Mo was applied to a LiNi_0.6Co_0.2Mn_0.2O₂ cathode to enhance the interfacial stability between the cathode and sulfide electrolyte. The source ions (Zr and Mo) coated on the precursor-surface diffused into the structure during the heating process, and influenced the structural parameters. This indicated that the coating ions acted as dopants. They also formed a homogenous coating layer, which are expected to be layers of Li-Zr-O or Li-Mo-O, on the surface of the cathode. The composite electrodes containing the surface-modified LiNi_0.6Co_0.2Mn_0.2O₂ powders exhibited enhanced electrochemical properties. The impedance value of the cells and the formation of undesirable reaction products on the electrodes were also decreased due to surface modification. These results indicate that the precursor-based surface modification using Zr and Mo is an effective method for suppressing side reactions at the cathode/sulfide electrolyte interface.

• 한국분말재료학회지
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• 제11권3호
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• pp.247-252
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• 2004

Recently, it has been found that mechanical alloying (MA) facilitates the nanocomposites formation of metal-metal oxide systems through solid-state reduction during ball milling. In this work, we studied the MA effect of Fe$_{3}$O$_{4}$-M (M = Al, Ti) systems, where pure metals are used as reducing agents. It is found that composite powders in which $Al_{2}$O$_{3}$ and TiO$_{2}$ are dispersed in $\alpha$-Fe matrix with nano-sized grains are obtained by mechanical alloying of Fe$_{3}$O$_{4}$ with Al and Ti for 25 and 75 hours, respectively. It is suggested that the large negative heat associated with the chemical reduction of magnetite by aluminum is responsible for the shorter MA time for composite powder formation in Fe$_{3}$O$_{4}$-Al system. X-ray diffraction results show that the reduction of magnetite by Al and Ti if a relatively simple reaction, involving one intermediate phase of FeAl$_{2}$O$_{4}$ or Fe$_{3}$Ti$_{3}$O$_{10}$. The average grain size of $\alpha$-Fe in Fe-TiO$_{2}$ composite powders is in the range of 30 nm. From magnetic measurement, we can also obtain indirect information about the details of the solid-state reduction process during MA.

• 대한금속재료학회지
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• 제49권10호
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• pp.790-796
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• 2011

To reduce the heat released during intermetallic reaction, Ni-50at%Al powder compact has been previously annealed at several conditions before the reaction. The effects of the pre-annealing conditions on the reaction synthesis process have been investigated. Experimental results show that the heat released during the reaction synthesis decreased proportionally with increase of the pre-annealing temperature and duration time. The reaction duration period was significantly increased when the intermetallics were formed in the powder compact during the pre-annealing. This was attributed to the fact that the reaction occurred by solid-state diffusion between the un-reacted elemental atoms and that the $NiAl_3$ phase formed predominantly during pre-annealing.

• 한국세라믹학회지
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• 제42권5호
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• pp.319-325
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• 2005

[ $LiNiO_2$ ] was synthesized by the solid-state method after mixing $LiOH{\cdot}H_2O$ and $Ni(OH)_2$ with SPEX mill. The optimum condition for the synthesis of $LiNiO_2$ was the calcination at $750^{\circ}C$ for 30h in $O_2$ stream after milling for 1 h. The $LiNiO_2$ synthesized under this condition showed relatively large value of $I_{003}/I_{104}$ and relatively small value of R-factor. When $LiNiO_2$ was cycled in 2.7$\~$4.15 V at 0.1C-rate, the first discharge capacity was not very large (145.8 mAh/g) but it showed good cycling performance. When $LiNiO_2$ was cycled in 2.7$\~$4.2 V at 0.1C-rate, the first discharge capacity was large but ,it showed poor cycling performance probably because of the transition of H2 hexagonal structure to H3 hexagonal structure. In addition, when $LiNiO_2$ was cycled in 1.0$\~$4.8 V at 1/24C- rate, the first discharge capacity was very large (257.7 mAh/g) and the discharge capacity increased with the number of cycles.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.383-390
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• 2001

We have investigated the L $i_{1+x}$M $n_2$ $O_4$system as a cathode material for lithium rechargeable batteries. To improve the cycle performance of spinel LiM $n_2$ $O_4$ as the cathode of 4V class lithium secondary batteries, spinel phase L $i_{1+x}$M $n_2$ $O_4$(x=0, 0.025, 0.05, 0.075) was prepared at 75$0^{\circ}C$ for 48h. The preparation of L $i_{1+x}$M $n_2$ $O_4$ from L $i_2$ $O_3$ and Mn $O_2$ under air is studied. The compounds were synthesized by using solid-state reaction. Structural refinements were carried out with a Rietveld-refinement program. Electrochemical properties were examined using the Li/L $i_{1+x}$M $n_2$ $O_4$ cells. The capacity of L $i_{1+x}$M $n_2$ $O_4$ decreases with increases lithium content, while the cycle life improves. The initial discharge capacity are 118mAh/g and 116mAh/g for LiM $n_2$ $O_4$ decreases with increases lithium content, while the cycle life improves. The initial discharge capacity are 118mAh/g and 116mAh/g for LiM $n_2$ $O_4$ and L $i_{1.025}$M $n_2$ $O_4$, respectively.pectively.