• Bulletin of the Korean Chemical Society
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• v.8 no.1
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• pp.6-9
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• 1987

The study of the $Na_3YSi_3O_9$ structure, by x-ray diffraction and infrared spectrum, showed that $Na_3YSi_3O_9$ is similar to $Na_4CaSi_3O_9$ except for its being pseudo-cubic instead of cubic. The peaks in the x-ray diffraction pattern of $Na_3YSi_3O_9$ could therefore be indexed on the basis of the $Na_4CaSi_3O_9$ cell. Also, modified $Na_3MSi_3O_9$ (M = Lu, Yb, Tm, Er, Y, Ho, Dy, Gd, Eu, and Sm) type compounds were synthesized by introducing excess sodium, decreasing M(III) concentration, and substituting small amount of phosphorus for silicon. The unit cell parameters of the composition $Na_{3.2}M_{0.7}Si_{2.9}P_{0.1}O_{8.7}$ were estimated from x-ray powder diffraction patterns using the Cohen method.

• Journal of Pharmaceutical Investigation
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• v.21 no.3
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• pp.125-132
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• 1991

Using X-ray crystallography powder diffraction, the quantitative representation method of preferred orientation of particles ill tablets was developed. Selected faces of a tablet. the upper surface and faces cut parallel and normal to the upper surface, were presented to an X-ray beam and X-ray diffraction patterns for these faces were measured. The effects of particle size. tableting pressure, and particle form on the preferred orientation were also investigated. It was also recognized that the degree of anisotropy in terms of capping tendency was influenced by the preferred orientation of particles in tablets.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2002.11a
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• pp.97-117
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• 2002

A chemoinfometrical method for quantitative determination of crystal content of indomethacin (IMC) polymorphs based on fourie-transformed near-infrared (FT-NIR) spectroscopy was established. A direct comparison of the data with the ones collected from using the conventional powder X-ray diffraction method was performed. Pure $\alpha$ and ${\gamma}$ forms of IMC were prepared using published methods. Powder X-ray diffraction profiles and NIR spectra were recorded for six kinds of standard materials with various content of ${\gamma}$ form IMC. The principal component regression (PCR) analyses were performed based on normalized NIR spectra sets of standard samples of known content of IMC ${\gamma}$ form. A calibration equation was determined to minimize the root mean square error of the prediction. The predicted ${\gamma}$ form content values were reproducible and had a relatively small standard deviation. The values of ${\gamma}$ form content predicted by two methods were in close agreement. The results were indicated that NIR spectroscopy provides for an accurate quantitative analysis of crystallinity in polymorphs compared with the results obtained by conventional powder X-ray diffractometry.

• Journal of Powder Materials
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• v.20 no.1
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• pp.53-59
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• 2013

Fe-TiC composite powder was fabricated via two steps. The first step was a high-energy milling of FeO and carbon powders followed by heat treatment for reduction to obtain a (Fe+C) powder mixture. The optimal condition for high-energy milling was 500 rpm for 1h, which had been determined by a series of preliminary experiment. Reduction heat-treatment was carried out at $900^{\circ}C$ for 1h in flowing argon gas atmosphere. Reduced powder mixture was investigated by X-ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM) and Laser Particle Size Analyser (LPSA). The second step was a high-energy milling of (Fe+C) powder mixture and additional $TiH_2$ powder, and subsequent in-situ synthesis of TiC particulate in Fe matrix through a reaction of carbon and Ti. High-energy milling was carried out at 500 rpm for 1 h. Heat treatment for reaction synthesis was carried out at $1000{\sim}1200^{\circ}C$ for 1 h in flowing argon gas atmosphere. X-ray diffraction (XRD) results of the fabricated Fe-TiC composite powder showed that only TiC and Fe phases exist. Results from FE-SEM observation and Energy-Dispersive X-ray Spectros-copy (EDS) revealed that TiC phase exists uniformly dispersed in the Fe matrix in a form of particulate with a size of submicron.

• Journal of Magnetics
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• v.22 no.1
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• pp.100-103
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• 2017

We studied the microstructure and magnetic properties of Fe nanosized powder synthesized by the pulsed wire evaporation method. The x-ray diffraction spectrum confirmed that this powder had a pure ${\alpha}$-Fe phase. Scanning electron microscope and transmission electron microscope measurements indicated that the prepared powder had uniform spherical shape with core-shell structure. The mean powder size was about 35 nm and the thickness of the surface passivation layer was about 5 nm. Energy dispersive X-ray spectroscopy measurement indicated that the surface passivation layer was iron oxide. Magnetic field dependent magnetization measurement at room temperature showed that the maximum magnetization of the prepared powder was 177.1 emu/g at 1 T.

• Journal of the Korean Ceramic Society
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• v.45 no.3
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• pp.146-149
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• 2008

Strontium-substituted $Sr_{1-x}Ba_xAl_2O_4:Eu^{2+},\;Dy^{3+}$ compositions were prepared by the solid state synthesis method. These compositions were characterized for their phase, crystallinity and morphology using powder x-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Photoluminescence properties were investigated by measuring excitation spectra, emission spectra and decay time for varying Ba/Sr concentrations. Photoluminescence results show higher luminescence and long decay time for $Sr_{1-x}Ba_xAl_2O_4:Eu^{2+},\;Dy^{3+}$(x=0). This is probably due to the influence of the 5d electron states of $Eu^{2+}$ in the crystal field. Long persistence was observed for these compositions due to $Dy^{3+}$ co-doping.

• Journal of Powder Materials
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• v.21 no.3
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• pp.207-214
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• 2014

In this study, nano-scale copper powders were reduction treated in a hydrogen atmosphere at the relatively high temperature of $350^{\circ}C$ in order to eliminate surface oxide layers, which are the main obstacles for fabricating a nano/ultrafine grained bulk parts from the nano-scale powders. The changes in composition and microstructure before and after the hydrogen reduction treatment were evaluated by analyzing X-ray diffraction (XRD) line profile patterns using the convolutional multiple whole profile (CMWP) procedure. In order to confirm the result from the XRD line profile analysis, transmitted electron microscope observations were performed on the specimen of the hydrogen reduction treated powders fabricated using a focused ion beam process. A quasi-statically compacted specimen from the nano-scale powders was produced and Vickers micro-hardness was measured to verify the potential of the powders as the basis for a bulk nano/ultrafine grained material. Although the bonding between particles and the growth in size of the particles occurred, crystallites retained their nano-scale size evaluated using the XRD results. The hardness results demonstrate the usefulness of the powders for a nano/ultrafine grained material, once a good consolidation of powders is achieved.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.158-163
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• 1985

The anodic oxidations of the Silver(I) / Silver(II) / Silver(III) system have been studied in aq. 2M $AgNO_3$ solution with Platinum and Carbon electrodes. It has been found that $Ag_7O_8NO_3$ can be produced at relatively higher current density. Deposited black Oxy-salt were analyzed with several methods such as oxidizing power, X-ray powder diffraction patterns, thermal analysis, and reduction curves. It decomposed to AgO upon being suspended in boiling water. AgO compound obtained from $Ag_7O_8NO_3$ were purer and denser than Alfa-product AgO.

• Journal of Powder Materials
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• v.6 no.2
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• pp.171-177
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• 1999

Ti-45.2at.%Ni-5at.%Cu and Ti-40.2at.%Ni-10atat.%Cu alloy powders were fabricated by gas atomization process. The microstructures, Shape, hardness and phase transformation behaviors of the powders were investigated by means of optical microscopy, scanning electron microscopy, micro-hardness measurement, x-ray diffraction analyses and differential scanning calorimetry. The hardness of the Ti-Ni-XCu alloy powders decreased as Cu-content increased. The x-ray diffraction analyses were carried out for powders without heat treatment, and those that treated at 85$0^{\circ}C$ for an hour in a vaccum state($10^5$ torr) and then quenched into ice water. The intensity of B$19^t$ phase increased with heat treating. The monoclinic B$19^t$ martensite was formed in the Ti-Ni-XCu alloy powders during cooling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3315-3318
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• 2012

In this study, Fe-base alloy powder was prepared by gas atomizing method. Shape and crystal structure of the powder were investigated by FESEM, X-ray diffraction, and DSC. The powder was produced in a spherical shape, with a size of 45 ~ 90 ${\mu}m$. X-ray diffraction analysis revealed that the powder was fully amorphous, showing typical broad amorphous peak. From DSC analysis, Tg and Tx that are generally found in a bulk amorphous alloy were also observed in the alloy powder. Tg and Tx of the powder were $530^{\circ}C$ and $560^{\circ}C$, respectively. These results suggest us that the bulk amorphous alloy (BMG) powder prepared in this study is applicable to laser welding.