• Journal of the Korean Ceramic Society
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• v.40 no.4
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• pp.380-384
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• 2003

The effects of the mole concentrations of precursor solution on the microstructure and dielectric properties of sol-gel deposited $Ba_{0.85}$S $r_{0.15}$Ti $O_3$(BST) thin films have been investigated. The films were of single perovskite phase with strong (100) preferred orientation when grown on LaNi0$_3$ buffered Pt/Ti/ $SiO_2$Si substrates using a diluted precursor solution. Variation of the precursor solution concentration resulted in a different microstructure and, in turn, affected the tunability of the sol-gel deposited films. It was observed that leakage currents increased asymmetrically for the negative and positive bias voltage with decreasing thickness. Overall results suggest that those BST films have acceptable properties f3r applications as room-temperature tunable elements.

• Journal of Powder Materials
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• v.18 no.1
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• pp.35-40
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• 2011

LAS-system ceramic powder, spodumene ($Li_2O{\cdot}Al_2O_3{\cdot}4SiO_2$), was successfully synthesized by a chemical solution technique employing PVA(polyvinyl alcohol) as an organic carrier. The PVA content affected the microstructure of porous precursor gels and the crystalline development. The optimum PVA content contributed to homogeneous distribution of metal ions in the precursor gel and it resulted in the synthesis of glass free $\beta$-spodumene powder having a specific surface area of $7.57\;m^2/g$. The agglomerated $\beta$-spodumene powders were also enough soft to grind to fine powders by a simple ball milling process. The microstructures of the densified powder compacts were strongly dependant on the minor phases of spodumene solid solution and amount of liquid phase, which were formed from the inhomogeneous precursors.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.1019-1027
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• 2013

Sulfur hexa-fluoride has been used as a etching gas in semiconductor industry. From the globally environmental issues, it is urgent to control the emissions of this significant greenhouse gas. The main objective of this experimental investigation was to find the effective catalyst for $SF_6$ decomposition. The precursor catalyst of hexa-aluminate was prepared to investigate the catalytic activity and stability. The precursor catalyst of hexa-aluminate was modified with Ni to enhance the catalytic activities and stability. The catalytic activity for $SF_6$ decomposition increased by the addition of Ni and maximized at 6wt% addition of Ni. The addition of 6wt% Ni in precursor catalyst of hexa-aluminate improved the resistant to the HF and reduced the crystallization and phase transition of catalyst.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.5-12
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• 1999

By the PVA-precursor method, polycrystalline powder of $Li_xNi_{1-y}Co_yO_2$, cathode material for lithium battery, was synthesized. Using the powder as the cathode material, lithium ion batteries were fabricated, whose electrochemical properties were measured. The effect of changing synthetic conditions, such as PvA/metal mole ratio, concentration of PVA, degree of polymerization of PVA, pyrolysis condition, and metal stoichiometry, on the battery performance was investigated. Considering the initial performance of the cell, the optimum stoichiometry of the $Li_xNi_{1-y}Co_yO_2$, synthesized by the PVA-precursor method was observed to be x: 1.0 and y=0.26. A minor phase of $Li_2CO_3$, which was generated by the residual carbon in the powder precursor, deteriorated the performance of the cell. In order to eliminate the minor phase, the precursor had to be pyrolyzed under the flow of dry air. Annealing the powder at $500^{\circ}C$ under the flow of dry air also eliminated the minor phase, and the performance of the cell was largely improved by the treatment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.3
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• pp.93-97
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• 2015

To synthesis of high purity micro silver particle, we extracted the silver from the waste by liquid-liquid extraction and used the rapid firing-liquid phase precursor (RF-LPP) method. The silver micro particle was synthesized at $500^{\circ}C$ for 3 hr in air atmosphere by RF-LPP method. As a result of the research, micro silver particle is measured X-ray diffraction (XRD), the main peak is nearly corresponded to the same as JCPDS card (No.87-0719). With using the RF-LPP method, the fine Ag micro particle indicated due to the control of nucleation site and the oxygen contents was decreased by reducing treatment. We expect this research contribute to advance in field of the recycling technology.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.236.2-236.2
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• 2015

The copper-zinc(Cu-Zn) nanofiber was prepared by electrospinning method. The Cu/PVP (polyvinylpyrrolidone) and Zn/PVP precursor solutions were prepared by dissolution of copper sulfate and zinc acetate in methanol, respectively. The PVP was used to control the viscosity of the precursor solutions. The optimized ratio for the Cu/PVP and Zn/PVP nanofibers was determined separately. Then the suitable ratio of the precursor solutions was applied for fabrication of Cu/Zn/PVP nanofiber. For the electrospinning method, the precursor solutions were filled in a syringe. The distance between metallic needle on the syringe and collector was fixed at 16 cm and the voltage was applied on the tip was 13.0 kV. And the as-spun nanofiber was heated at 353K for removal of residual solvent. Then the heated nanofibers were calcined at 973K to decompose PVP. The obtained Cu, Zn, and Cu-Zn nanofibers were investigated with X-ray photoelectron spectroscopy (XPS) for the chemical properties, scanning electron microscopy (SEM) for the morphologies, and X-ray diffraction (XRD) to characterize the crystallinity and phase of nanofibers.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.411-417
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• 1996

Ultrafine NiO/YSZ (Yttria Stabilized Zirconia) powders were made by using a glycine nitrate process which is used as anode material for solid oxide fuel cells. The specific surface areas of synthesized NiO/YSZ powders were examined with controlling pH of a precursor solution and the content of glycine. The binding of glycine with metal nitrates occurring in the precursor solution was analyzed by using FTIR. The characteristics of synthesized powders were examined with X-ray diffraction(XRD) Brunauer Emmett Teller with N2 absorption. scanning electron microscopy (SEM). and transmission electron microscopy (TEM). Ultrafine NiO/YSZ powders of 15-18 m2/g were obtained through GNP when the content of glycine was controlled to 1 or 2 times the stoichiometric ratio in the precursor solutions. Strongly acid precursor solution increased the specific surface area of the synthesized powders. This is suggested to be the increased binding of metal nitrates and glycine under a strong acid solution of pH=0.5 that lets glycine consist of mainly the amine group of {{{{ { NH}`_{3 } ^{+ } }}. After sintering and reducing treatment of NiO/YSZ powders synthesized by GNP the Ni/YSZ pellet showed ideal microstructure where very fine Ni particles of 3-5 ${\mu}{\textrm}{m}$ were distributed uniformly and fine pore around Ni metal particles was formed. leading to anincrease of the triple phase boundary among gas Ni and YSZ.

• The Korean Journal of Ceramics
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• v.6 no.1
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• pp.32-36
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• 2000

Pyrolytic preparations of Ti-Al-N ceramics from three blended precursors were investigated. The precursors were prepared stirring ($HA1N^{i}Pr_m$ and an aminolysis product of $Ti(NMe_2)_4$ with $MeHNCH_2CH_2$NHMe in $C_6/H_6$ . IR and $^1H\;NMR $analyses suggested that essentially no Ti-N-Al bonds were present in the precursors. Pyrolysis of the precursors under $NH_3-N_2$led to the formation of brown solids with ceramic yields of about 30%, and the Ti-Al ratios in the pyrolyzed products were close to those of the precursors. XRD analysis of the pyrolyzed product from the precursor with Ti:Al=5:1 indicated the formation of a NaCl-type compound as the only crystalline phase. Pyrolysis of the precursor with Ti:Al=2:1 led to the formation of AlN besides the major NaCl-type compound. A ceramic composite containing AlN and the NaCl-type compound was formed by pyrolysis of the precursor with Ti:Al=1:2.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.294-297
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• 2008

In this paper, a novel non-vacuum technique is described for the fabrication of a $CuInSe_2$ (CIS) absorber layer for thin film solar cells using a low-cost precursor solution. A solution containing Cu- and Inrelated chemicals was coated onto a Mo/glass substrate using the Doctor blade method and the precursor layer was then selenized in an evaporation chamber. The precursor layer was found to be composed of CuCl crystals and amorphous In compound, which were completely converted to chalcopyrite CIS phase by the selenization process. Morphological, crystallographic and compositional analyses were performed at each step of the fabrication process by SEM, XRD and EDS, respectively.

• Journal of architectural history
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• v.23 no.1
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• pp.51-62
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• 2014

Architecture is a product of numerous influences, as shown in the apprenticeships of Kim, Jung-Up and Kim, Swoo-Geun with Le Corbusier's influences. Therefore, its identity is need to be re-defined based on such complex relationships. The rhetorical images of 'the Map of Misreading', as the core of the poetic identification proposed by Harold Bloom's 'the Theory of Influence', provide an efficient way of explaining the relations between architectural apprenticeships and identities. This research is to re-build a new methodology of architectural criticism based on it. The diachronic transformations of the architecture of Seung, Hyo-Sang also had very characteristic 'revisionary ratios' about his precursor Kim, Swoo-Geun. As an antithetic stance of his precursor's final phase, his early days works pursued continuously geometric abstraction and objective images of the architecture of Adolf Loos. However, his recent works are showing the obvious symptoms of regression to his origins. Finally, the architectural identity should be re-conceptualized as a complexity, based on inter-textuality from complex influences. This new architectural identity can be reflected into the modern obsessive identity.