• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.305-312
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• 1995

Thin films of Pb(Mg, Zn)1/3Nb2/3O3 were fabricated by spin coating the Pb-Mg-Zn-Nb-O complex alkoxide sols on(111) Pt-coated MgO (100) planes. It was observed that the content of H2O and the rheological characteristics of sol greatly influenced the orientation of perovskite grains after thin-film formation. A strong preferential orientation of (100)-type planes of the perovskite grains was obtained for the sol aged for 15 days with the molar ratio of H2O to total metal alkoxides=2. As small angle X-ray scattering experiment in the Porod region was performed to correlate the observed preferential orientation with the network structure of precursors at various stage of aging. It was shown that the degree of branching of the Pb-Mg-Zn-Nb-O precursor chain had a direct effect on the preferred oreintation, and weakly branched precursor systems led to highly oriented grains after thin-film formation.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.182-191
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• 2024

Li(Ni_xCo_yMn_1-x-y)O₂ (NCM) is the intensively developed cathode material for expanding the electric vehicle market and developing lithium-ion batteries that meet higher capacity, longer life, and lower cost. High-nickel NCM increases the nickel content to 80% or more, securing price competitiveness by improving performance with high energy density and reducing the cost of cobalt. However, the high-nickel NCM materials have a residual lithium problem, leading to issues in battery performance degradation and stability. While various methods exist for removing residual lithium, such as washing, doping, and coating, this paper focuses on recent research trends in coatings aimed at enhancing NCM performance and stability by removing residual lithium.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.875-881
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• 2004

Fundamental results obtained from an atomic force microscope (AFM) chemically-induced direct nano-lithography process are presented, which is regarded as a simple method for fabrication nm-scale devices such as superconducting flux flow transistors (SFFTs) and single electron tunneling transistors (SETs). Si cantilevers with Pt coating and with 30 nm thick TiO coating were used as conducting AFM tips in this study. We observed the surfaces of superconducting strip lines modified by AFM anodization' process. First, superconducting strip lines with scan size 2 ${\mu}{\textrm}{m}$${\times}$2 ${\mu}{\textrm}{m}$ have been anodized by AFM technology. The surface roughness was increased with the number of AFM scanning, The roughness variation was higher in case of the AFM tip with a positive voltage than with a negative voltage in respect of the strip surface. Second, we have patterned nm-scale oxide lines on ${YBa}-2{Cu}_3{O}_{7-x}$ superconducting microstrip surfaces by AFM conductive cantilever with a negative bias voltage. The ${YBa}-2{Cu}_3{O}_{7-x}$ oxide lines could be patterned by anodization technique. This research showed that the critical characteristics of superconducting thin films were be controlled by AFM anodization process technique. The AFM technique was expected to be used as a promising anodization technique for fabrication of an SFFT with nano-channel.

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.149-152
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• 1991

We report a new method of fabricating a Ti:LiNb03 waveguide with no out-diffusion by coating the waveguide with $SiO_2$ thin film. It was coated before diffusion process, and the $LiO_2$ out-diffusion was prevented in the diffusion process. We compare the near field patterns of the guided modes between the typical waveguide and the waveguide fabricated by new method proposed here.

• Journal of Welding and Joining
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• v.14 no.6
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• pp.109-118
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• 1996

Al$_2$O$_3$-TiO$_2$powders of six different compositions were plasma-sprayed on Ti substrate. The spray powders and the spray coated layers were analysed and compared using SEM and X-RD. The elastic properties (specific elastic constant and damping coefficient) of the coated specimens were measured in order to select the optimum composition range of ceramics for use in a speaker diaphragm. A correlation between the microstructure and elastic properties was also investigated. When $Al_2$O$_3$powders with 0- 13% TiO$_2$were plasma sprayed, the coated layers were composed of metastable y-Al$_2$O$_3$with small amount of $\alpha$-Al$_2$O$_3$and the content of $\alpha$-Al$_2$O$_3$was increased with TiO$_2$content. Specific elastic constant was rapidly increased with 2 and 13% TiO$_2$addition to $Al_2$O$_3$. The internal damping was nearly unchanged with TiO$_2$content The specific elastic constant seemed to be dependent on the content of $\alpha$-Al$_2$O$_3$in the coated layer.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.447-453
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• 2011

The monodisperse spherical $SiO_2$ particles were overcoated with $Y_2O_3:Eu^{3+}$ phosphor layers via a Pechini sol-gel process and the resulting $SiO_2@Y_2O_3:Eu^{3+}$ core-shell phosphors were subsequently annealed at $800^{\circ}C$ at an ambient atmosphere. The crystallographic structure, morphology, and luminescent property of core-shell structured $SiO_2@Y_2O_3:Eu^{3+}$ phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL). The spherical, nonagglomerated $SiO_2$ particles prepared by a Stober method exhibited a relatively narrow size distribution in the range of 260-300 nm. The thickness of phosphor shell layer in the core-shell particles can be facilely controlled by varying the coating number of $Y_2O_3:Eu^{3+}$ phosphors. The core-shell structured $SiO_2@Y_2O_3:Eu^{3+}$ phosphors showed a strong red emission, which was dominated by the $^5D_0-^7F_2$ transition (610 nm) of $Eu^{3+}$ ion under the ultraviolet excitation (263 nm). The PL emission properties of $SiO_2@Y_2O_3:Eu^{3+}$ phosphors were also compared with pure $Y_2O_3:Eu^{3+}$ nanophosphors.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.87-88
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• 2006

Ceramic-Metal Functionally Graded Materials (FGM) are of great interest for application as Thermal Barrier Coating (TBC) or Wear Resistant Coating (WRC). Spark Plasma Sintering (SPS) is a promising techniques for time-saving consolidation of laminated/graduated powder systems: SPS is a pressure-assisted electrical sintering method which directly applies a pulsed DC current as heat source. In the present work, production of $Al_2O_3-Ni$ FGMs by means of Spark Plasma Sintering is considered; effect of sintering condition on density, hardness and fracture toughness is studied. Problems correlated to this new processing technology are discussed.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1516-1522
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• 2014

A series of 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ surface treatments were applied to $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates. The $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates were synthesized using a co-precipitation method. Sample (a) was left pristine and variations of the 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ were applied to samples (b), (c) and (d). XRD was used to verify the space group of the samples as R$\bar{3}$m. Additional morphology and particle size data were obtained using SEM imagery. The $Al_2O_3$ coating layers of sample (b) and (d) were confirmed by TEM images and EDS mapping of the SEM images. 2032-type coin cells were fabricated in a glove box in order to investigate their electrochemical properties. The cells were charged and discharged at room temperature ($25^{\circ}C$) between 2.0V and 4.8V during the first cycle. The cells were then charged and discharged between 2.0V and 4.6V in subsequent cycles. Sample (d) exhibited lower irreversible capacity loss (ICL) in the first charge-discharge cycle as compared to sample (c). Sample (d) also had a higher discharge capacity of ~250 mAh/g during the first and second charge-discharge cycles when compared with sample (c). The rate capability of the $Al_2O_3$-coated sample (b) and (d) was lower when compared with sample (a) and (c). Sample (d), coated with $Al_2O_3$ after the surface treatment with $(NH_4)_2SO_4$, showed an improvement in cycle performance as well as an enhancement of discharge capacity. The thermal stability of sample (d) was higher than that of the sample (c) as the result of DSC.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.479-484
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• 2011

In this paper, investigations of thick film $La_{0.75}Sr_{0.25}Ga_{0.8}Mg_{0.16}Fe_{0.04}O_{3-{\delta}}$ (LSGMF) cells fabricated via spin coating on either NiO-YSZ anode or $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_3$ (LSGF) cathode substrates are presented. A La-doped $CeO_2$ (LDC) layer is inserted between NiO-YSZ and LSGMF in order to prevent reactions from occurring during co-firing. For the LSGF cathode-supported cell, no interlayer was required because the components of the cathode are the same as those of LSGMF with the exception of Mg. An LSGMF electrolyte slurry was deposited homogeneously on the porous supports via spin coating. The current-voltage characteristics of the anode and cathode supported LSGMF cells at temperatures between $700^{\circ}C$ and $850^{\circ}C$ are described. The LSGF cathode supported cell demonstrates a theoretical OCV and a power density of ~420 mW $cm^2$ at $800^{\circ}C$, whereas the NiO-YSZ anode supported cell with the LDC interlayer demonstrates a maximum power density of ~350 mW $cm^2$ at $800^{\circ}C$, which decreased more rapidly than the cathode supported cell despite the presence of the LDC interlayer. Potential causes of the degradation at temperatures over $700^{\circ}C$ are also discussed.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.94-97
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• 2004

Micro/nano-sized L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ particles are considered to improve oxygen permeability in highly selective inorganic oxygen separation membrane. A L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membrane with perovskite structure is fabricated by a conventional solid-state reaction. As the oxygen permeation flux of the L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membrane was lower than commercial gas separation membranes, we coated the L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ particles to enhance the oxygen permeation flux. It has been demonstrated that the effective area of reactive free surface is an important factor in determining the effectiveness of the introduction of coating layer for oxygen permeation. The introduction of micro/nano L $a_{0.6}$S $r_{0.4}$Co $O_{3-}$$\delta$/ particles was very effective for increasing oxygen flux, as the flux was as much as 2 to 6 times higher than that of an uncoated L $a_{0.7}$S $r_{0.3}$G $a_{0.6}$F $e_{0.4}$ $O_{3-}$$\delta$/ membrane.\delta$/ membrane.>/ membrane.brane.