• 한국세라믹학회지
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• 제47권6호
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• pp.627-632
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• 2010

In this paper the effect of the structure, particle size, morphology of nanofibers and nanoparticles for the electrochemical characteristics of $Li_4Ti_5O_{12}$ was investigated. The $H_2Ti_2O_5{\cdot}H_2O$ synthesized in hydrothermal treatment from a NaOH treatment on $TiO_2$ by ion exchange processing with HCl solutions. After the $Li_4Ti_5O_{12}$ nanofibers synthesized in hydrothermal treatment of $H_2Ti_2O_5{\cdot}H_2O$ and $LiOH{\cdot}H_2O$. The hydrogen titanate precursor prepared by ion exchange processing with 0.1~0.3M HCl solutions and the final products calcined at $350^{\circ}C{\sim}400^{\circ}C$. The $Li_4Ti_5O_{12}$ nanofibers showed well reversibility during the insertion and extraction of Li, good cycle performance, high capacity and low electrochemical reaction resistance than nanoparticles. also c-rate exhibited a discharge capacity of 172 mAh/g at 0.2C and 115mAh/g at 5C, which is the 77%, 67% of that obtained in the process charged, discharged at 0.2C.

• 한국세라믹학회지
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• 제51권1호
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• pp.1-6
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• 2014

Here we report improved photo-catalytic effect of $Ag_2S$ under visible light using carbon nano-tubes (CNT) modified with $Ag_2S$ nanoparticles. The optical properties, structural properties and compositional analysis, as well as the photo-electrochemical properties of the prepared composites were investigated. It was found that the photocurrent density, and the photo-catalytic effect, was increased by modification of CNT in this way. Compared with the separate effects of $Ag_2S$ and CNT nanoparticles, the photocatalytic effect of CNT-modified-with-$Ag_2S$ composites, increased significantly due to a synergistic effect between the CNT and the $Ag_2S$ nanoparticles.

• 한국세라믹학회지
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• 제45권6호
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• pp.320-323
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• 2008

The preparation of $Zn_xMn_{1-x}Fe_2O_4$ nanoparticles in an Igepal CO-520-cyclohexane water reverse micelle solution has been studied. The transmission electron microscopy and X-ray diffraction pattern analyses revealed the resulting particles to be $Zn_xMn_{1-x}Fe_2O_4$. The average size and distribution of the synthesized particles calcined at $500^{\circ}C$ for 5 h were in the range of 10 to 20 nm and broad, respectively. The phase of the synthesized particles was crystalline, the magnetic behavior of the synthesized particles was ferromagnetic. The effect of the synthesis parameters, such as the molar ratio of water to surfactant and calcination temperature, is discussed.

• 한국전기전자재료학회논문지
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• 제32권6호
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• pp.458-461
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• 2019

The facile synthesis of shape-controlled Pd nanoparticles (PdNPs) with ascorbic acid as a reducing agent and cetyltrimethylammonium bromide (CTAB) as a capping agent is presented in this study. The synthesized PdNPs were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman Spectroscopy. The prepared PdNPs show efficient surface-enhanced Raman scattering (SERS) properties. SERS studies on the adsorption characteristics of 1,4-phenylene diisocyanide (1,4-PDI) on colloidal PdNPs have revealed that the relative peak intensity of the $(NC)_{free}$ and $(NC)_{bound}$ modes distinctly depends on the 1,4-PDI concentration as well as the shape of the PdNPs. Furthermore, we found that the PdNPs are also efficient photoelectron emitters such that the SERS spectrum of 4-nitrobenzenethiol (4-NBT) on PdNPs is readily converted to that of 4-aminobenzenethiol (4-ABT) under 632.8 nm radiation.

• Current Applied Physics
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• 제18권11호
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• pp.1410-1414
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• 2018

Magnetic nanoparticles (MNP) have attracted considerable interest in many fields of research and applied science due to their impressive properties. In the past, especially biomedical problems have promoted the development of MNPs. For technical applications e.g. wastewater treatment and absorption of electromagnetic waves, the existing synthesis approaches are too expensive and/or the producible quantities are too low. In this work we present a method for simple preparation of size-controlled magnetic iron oxide nanoparticles by electroerosion dispersion (EED) of carbon steel in water. We describe the synthesis method, the laboratory installation and discuss the structural, chemical and electromagnetic properties of the synthetized EED powders as well as their applicability for microwave absorption compared to other available ferrite powders.

• 세라미스트
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• 제21권3호
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• pp.270-282
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• 2018

The increasing importance of biomedical imaging technology has led to the development of a variety of luminescent materials, including molecular fluorophores, fluorescent proteins, and quantum dots. Owing to their inherent disadvantages, such as insufficient chemical stability and limited biocompatability, their utilization has been limited with imaging only under highly optimized and controlled conditions. Recently, a new class of luminescent nanoparticles, upconversion nanoparticles (UCNPs), have been emerging as a practically useful nanoprobe for various bioimaging applications. The detailed synthesis, functionalization, properties and in-vitro / in-vivo applications of the UCNPs are introduced and discussed in this Review.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 2000년도 Proceedings of 2000 International Nano Crystals/Ceramics Forum and International Symposium on Intermaterials
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• pp.35-58
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• 2000

The demand for sub-micrometer or nanometer functional ceramic powders with a better suspension behavior in aqueous media in increasing. Redispersible barium titanate (BT) nanocrystals, green light emitting Mn2+ doped Zn$_2$SiO$_4$ and ZnS nanoparticle phosphors were synthesized by a hydrothermal method or chemical precipitation with surface modification. The nanoparticle redispersibility for BT was achieved by using a polymeric surfactant. X-ray diffraction(XRD) results indicated that the BT particles are of cubic phase with 80 nm in size. XRD results of zinc silicate phosphor indicate that seeds play an important role in enhancing the nucleation and crystallization of Zn$_2$SiO$_4$ crystals in a hydrothermal condition. This paper describes and discuss the methods of surface modification, and the resulting related properties for BT, zinc silicate and zinc sulfide.

• 한국세라믹학회지
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• 제55권6호
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• pp.625-634
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• 2018

In this work, we describe a novel and simple technique to produce non-hydrate surfactant complexes for the formation of highly crystalline fatty acid modified SPIONs by thermolysis of iron oleate (FeOl) complexes in a non-coordinating solvent. FeOl complexes were prepared by direct coordination of iron ions and carboxylic acid; thus, we could control the stoichiometric composition of the precursor by changing the molar ratio of fatty acid and metal ions. The discrete thermal behaviors and chemical coordination of the intermediate non-hydrated FeOl were studied by thermo-analytic techniques including differential scanning calorimetry, thermal gravimetric analysis, and Fourier transform infrared spectroscopy.

• 한국세라믹학회지
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• 제48권2호
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• pp.117-120
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• 2011

In this study, the redox state of iron in sodium silicate glasses was varied by changing the melting conditions, such as the melting temperature and particle size of iron oxide. The oxidation states of the iron ion were determined by wet chemical analysis and UV-Vis spectroscopy methods. Iron commonly exists as an equilibrium mixture of ferrous ions, $Fe^{2+}$, and ferric ions $Fe^{3+}$. In this study, sodium silicate glasses containing nanoparticles of iron oxide (0.5% mol) were prepared at various temperatures. Increase of temperature led to the transformation of ferric ions to ferrous ions, and the intensity of the ferrous peak in 1050 nm increased. Nanoparticle iron oxide caused fewer ferrous ions to be formed and the $\frac{Fe^{2+}}{Fe^{3+}}$ equilibrium ratio compared to that with micro-oxide iron powder was lower.

• 한국세라믹학회지
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• 제43권4호
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• pp.224-229
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• 2006

Ag-Pd alloy nanoparticles were prepared by a chemical reduction method using hydrazine $(N_2H_4)$ as a reductant in $AgNO_3\;and\;Pd(NO_3)_2$ aqueous solutions. Characterization of these particles by X-ray powder diffraction revealed a bimetallic and crystalline silver-palladium alloy. The average size of the particles was influenced not by the reductant $(N_2H_4)$ concentration, but the concentration of the starting materials $(AgNO_3\;and\;Pd(NO_3)_2)$.