• Textile Coloration and Finishing
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• v.8 no.3
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• pp.16-23
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• 1996

In order to know the change of weight loss, crystallinity, crystallite size(010) plane, and thermal properties of PET films which had before drawn and annealed at various temperature. It were treated in sodium triethylene glycolate-triethylene glycol(STEG-TEG) were prepared. The following results were abtain. The weight loss of PET films were increasing with increaing treated time in STEG-TEG solution and It showed a linear rlationship to the treated time. The crystallinity and crystallite size(010) plane of PET films decreased with increasing decomposition ratio when PET films were treated with before annealed under 16$0^{\circ}C$. The crystalline region on the surface of samples were decompose to thermal unstable crystalline structure

• Journal of Magnetics
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• v.18 no.1
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• pp.1-4
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• 2013

Structural and magnetic properties of $Fe_{50}Mn_{50}$ nanocrystalline alloys prepared by the mechanical alloying technique (using commercial Fe and Mn powders as the precursors) are studied as a function of milling time, 1 hr to 48 hrs. The nano-crystallite size and shape are examined by using scanning electron microscopy (SEM). The effect of milling time on structural characterization was investigated using X-ray diffractometer (XRD) and extended X-ray absorption fine structure spectroscopy (EXAFS). Both XRD and EXAFS studies showed that the alloying process should be completed after 36 hrs milling. Concerning the magnetic behavior, the data obtained from superconducting quantum interference devices (SQUID) exhibited both magnetic saturation ($M_s$) and coercivity ($H_c$) depend strongly on the milling time, which are related to the changes in the crystallite size and magnetic dilution.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.201-208
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• 2008

Ceria ($CeO_2$) becomes one of important functional nanomaterials and a key abrasive material for chemical-mechanical planarization (CMP) of advanced integrated circuits in silicon semi-conductor technology. Two synthetic crystalline ceria (RT735, RT835) are studied by the Rietveld structural refinement to determine crystallite size and microstrain. Rietveld indices of RT735 and RT835 indicate good fitting with $R_p(%)=8.50$, 8.34; $R_{wp}(%)=13.4$, 13.5; $R_{exp}(%)=11.3$, 11.5; $R_B(%)=2.21$, 2.36; S(GofF: Goodness of fit)=1.2, 1.2, respectively. $CeO_2$ with space group Fm3m show a=5.41074(2), 5.41130(6) ${\AA}$, V=158.406(1), 158.455(3)${\AA}^3$ in dimension. Detailed Rietveld refinement reveals that crystallite size and microstrain are 37.42(1) nm, 0.0026 (RT735) and 72.80(2) nm, 0.0013 (RT835), respectively. It also shows that crystallite size and microstrain of ceria are inversely proportional to each other.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.251-251
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• 2002

• Journal of Powder Materials
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• v.16 no.3
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• pp.203-208
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• 2009

$Y_2O_3$:Eu red phosphor was prepared by microwave synthesis. The crystal phase, particle morphology, and luminescent properties were characterized by XRD, SEM, and spectrofluorometer, respectively. The prepared $Y_2O_3$:Eu particles had good crystallinity and strong red emission under ultravioletet excitation. The crystallite size increased with calcination temperature and satuarated at $1200^{\circ}C$. The primary particle size initially formed was varied from 30 to 450 nm with microwave-irradiation (MI) time. It was found that the emission intensity of $Y_2O_3$:Eu phosphor strongly depends on the MI time. In terms of the emission intensity, it was recommended that the MI time should be less than 15 min. The emission intensity of $Y_2O_3$:Eu phosphor prepared by microwave syntehsis strongly depended on the crystallite size of which an optimal size range was 50-60 nm.

• Journal of the Korean institute of surface engineering
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• v.40 no.1
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• pp.11-15
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• 2007

Stable metallic Cu/Zn nanoparticles were prepared in the base oil phase by hydrothermal method. The physical properties, such as crystal structure, crystallite size and crystallinity according to synthesis conditions have been investigated by XRD, FT-IR and TEM. In addition, 4-ball test has been performed in order to investigate the frictional wear properties of prepared nanosized Cu/Zn particles. The peaks of the X-ray diffraction pattern indicate that the particle size was very small and crystallinity of Cu/Zn particles was good. The micrographs of TEM showed that nanosized Cu/Zn particles possessed a spherical morphology with a narrow size distribution. The crystallite size of the Cu/Zn particles synthesized in base oils was 23-30 nm. It was found that the antiwear capacity increases with increasing Cu/Zn concentration. When the concentration of Cu/Zn was 5.0 wt%, the wear scar diameters was 0.38 mm.

• Transactions on Electrical and Electronic Materials
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• v.12 no.4
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• pp.164-168
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• 2011

Nanocrystalline cadmium sulphide (CdS) thin films were prepared using chemical bath deposition (CBD), and the structural, optical and photoconductive properties were investigated. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size, dislocation density and lattice constant of CBD CdS thin films were investigated. The dislocation density of CdS thin films initially decreases with increasing film thickness, and it is nearly constant over the thickness of 2,500 ${\AA}$. The dislocation density decreases with increasing the crystallite size. The Urbach energies of CdS thin films are obtained by fitting the optical absorption coefficient. The optical band gap of CdS thin films increases and finally saturates with increasing the lattice constant. The Urbach energy and optical band gap of the 2,900 A-thick CdS thin film prepared for 60 minutes are 0.24 eV and 2.83 eV, respectively. The activation energies of the 2,900 ${\AA}$-thick CdS thin film at low and high temperature regions were 14 meV and 31 meV, respectively. It is considered that these activation energies correspond to donor levels associated with shallow traps or surface states of CdS thin film. Also, the value of ${\gamma}$ was obtained from the light transfer characteristic of CdS thin film. The value of ${\gamma}$ for the 2,900 A-thick CdS thin film was 1 at 10 V, and it saturates with increasing the applied voltage.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.178-182
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• 2010

Simultaneous removal reaction for NOx, soot over Pt catalysts using various $TiO_2$ as support was studied. The catalytic tests ware carried out injectin NO, soot, NO and soot simultaneously on each catalysts. As results, it showed different NOx removal efficiency and soot oxidation rate according to various kinds of $TiO_2$. Onset temperature of soot oxidation has a correlation to $NO_2$ generated for the independently performed NOx. It was investigated that NO to $NO_2$ oxidation was intimately related to crystallite size and surface area, and it has a tremendous impact on Pt aggregation on the catalyst surface and catalyst' reducibility. Therefore, we concluded that major index of the reaction was physico-chemical properties of catalyst' supports.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.195-202
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• 2013

$TiO_2$ powders were prepared from titanium (IV) sulfate ($Ti(SO_4)_2$) solution using ammonia solution at low reaction temperature ($80{\sim}100^{\circ}C$) and atmospheric pressure by hydrothermal precipitation method without calcination. The effect of reaction conditions, such as reaction temperature, initial concentration of titanium (IV) sulfate ($Ti(SO_4)_2$) solution, pH of mixture solution and the physical properties of the prepared $TiO_2$, such as crystallite structure, crystallite size were investigated. The photocatalytic activity of prepared $TiO_2$ was tested by the photolysis of brilliant blue FCF (BB-FCF) under the UV and the analysis of UV-VIS diffuse reflectance spectroscopy (DRS). The physical properties of prepared $TiO_2$ were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectrometer (PL), particle size distribution measurements. The crystallite size and crystallinity of prepared $TiO_2$ increased with increasing titanium (IV) sulfate ($Ti(SO_4)_2$) concentration, but photocatalytic activity decreased. The crystallite size decreased with increasing pH of mixture solution, but photocatalytic activity increased. The crystallinity and photocatalytic activity increased with increasing reaction temperature. The results showed that anatase type $TiO_2$ could be prepared by hydrothermal precipitation method using titanium (IV) sulfate ($Ti(SO_4)_2$) solution and ammonia solution at low reaction temperature and atmospheric pressure without calcination.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.73-76
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• 1997

Nanocrystalline materials have been modeled as a mixture of the crystallite and the grain boundary phases. The mechanical property has been calculated using the rule of mixtures based on the volume fractions. The critical grain size concept suggested by Nieh and Wadsworth and porous material model suggested by Lee and Kim were applied to the calculation. The theoretical results fit very well with the experimental values