• Journal of the Korean Ceramic Society
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• v.45 no.12
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• pp.821-826
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• 2008

Nanocrystallized glasses with the composition of $(50-x)BaO-xTiO_2-50SiO_2$ (x=10, 15, 16.7 and 20) have been prepared by heat-treatment at $T_x$ (crystallization onset temperature) for 3 h, and their optical properties, photoluminescence (PL), XRD and Raman spectra have been examined. The absorption edges of the glasses were red-shifted and the absorption coefficient increased with an increase of $TiO_2$. The glass subjected to the heat-treatment showed a dense formation of ${Ba_2}{TiSi_2}{O_8}$ crystals. The XRD and Raman results show that the nanocrystallized glasses formed fresnoite phase up to $TiO_2$ concentrations of 15 mol%. Further-more, blue luminescence with a peak at the wavelength of around 470nm was observed in the nanocrystallized glass, demon strating the optical multifunctional nanocrystallized material such as non-linear optics and photo-luminescence. It is thought that the blue luminescence from the ${Ba_2}{TiSi_2}{O_8}$ nanocrystallized glass originated from the presence of $Ti^{4+}$ incorporated into the fresnoite-type structure.

• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.897-907
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• 1997

Thin films of Bi4-xSmxTi3O12(0$\leq$x$\leq$2) were prepared on Pt/Ti/SiO2/Si(100) at $700^{\circ}C$ using spin-coating with sols derived from Bi-Sm-Ti complex alkoxides. From X-ray diffraction analysis, it was observed that Sm-substituted phases resembled ferroelectric Bi4Ti3O12 in structure. Variations of their lattice parameters depending on the amount of Sm-substitution showed that an anomalous structural distortion might exist at x=1. The grain sizes of the thin films decreased from 0.115 ${\mu}{\textrm}{m}$ to 0.078${\mu}{\textrm}{m}$ with increasing the amount of Sm-substitution. The dielectric constants and the remanent polarizations of the thin films decreased with increasing the amount of the Sm-substitution, which were related to decrease of the stereo-active Bi3+ ion contributing to polarization. However, these values were exceptionally high at x=1, compared to those of the other substituted phases. Such an anomaly suggests that the phase of x=1 has 1:1 chemical ordering between Sm and Bi in structure. The thin films of all compositions except x=2 showed ferroelectricity. The thin film of x=2 was paraelectric, whose grains were too fine to exhibit ferroelectricity.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.22-25
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• 2000

Polycrystalline SBTN layered ferroelectric thin film with various Nb mole ratios were prepared by sol-gel method Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperature and characterized in terms of phase and microstructure. The films were crystallized with a high (105) diffraction intensity and had rodike structure, SBTN films fired at 800$^{circ}C$ revealed standard hysteresis loops with no fatigue for up to 10$^{10}$ cycles. At an applied voltage of 5V the dielectric constant($varepsilon$) , dissipation factor (tan $delta$), remanent polarization(ZPr) and coercive field(Ec) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$) $O_{9+}$$alpha$/ thin film(x=0.1) prepared on Pt/ $SiO_2$/Si (100) were about 277.7, 0.042, 3.74$mu$C/$textrm{cm}^2$, and 24.8kv/cm respectively.ly.y. respectively.ly.y.y..

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.397-404
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• 2006

Effects of surface defect distribution on flame instability during flame-surface interaction are experimentally investigated. To examine chemical quenching phenomenon which is caused by radical adsorption and recombination processes on the surface, thermally grown silicon oxide plates with well-defined defect density were prepared. ion implantation technique was used to control the number of defects, i.e. oxygen vacancies. In an attempt to preferentially remove oxygen atoms from silicon dioxide surface, argon ions with low energy level from 3keV to 5keV were irradiated at the incident angle of $60^{\circ}$. Compositional and structural modification of $SiO_2$ induced by low-energy $Ar^+$ ion irradiation has been characterized by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). It has been found that as the ion energy is increased, the number of structural defect is also increased and non-stoichiometric condition of $SiO_x({\le}2)$ is enhanced.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.385-390
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• 1996

Cs는 AW500 에서 높은 분배계수 값(K$_{Cs}$>$10^3$$m\ell$/g)을 얻었으며 , Sr은 13X, 평형 용액의 pH=10의 조건에서 최대의 분배계수값(K$_{Sr}$~$10^4$$m\ell$/g)을 보였고, 평형용액의 pH 증가에 따라서 급격히 증가하는 경향을 보였다. 또한 AW500-Cs와 13X-Sr계는 고액비, 즉 V/m=40, 및 초기용액의 pH가 3 이상에서 최대의 분배계수 값을 얻었으며, 혼합제올라이트의 비(AW500/13X)가 1.5인 조건에서 Cs과 Sr을 효과적으로 동시에 분리할 수 있음 보았다. 그리고 1,10$0^{\circ}C$에서 배소한 AW500-Cs는 CsAlSi$_2$O$_{6}$로 재결정되며 , 13X-Sr은 SrAI$_2$Si$_2$O$_{8}$ 및 SiO$_2$상(phase)으로 재결정한다.

• Journal of the Korean Ceramic Society
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• v.25 no.1
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• pp.73-77
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• 1988

Single crystals of kalsilite were synthesized by hydrothermal method at 420$^{\circ}C$-480$^{\circ}C$ and 100 atm-1500 atm. The crystal habits are similar to those of KLiSiO4 single crystals. The crystal structure was investigated by means of X-ray single crystal diffraction. The space group of kalsilite is P63. Phase transitiions were determined by use of DTA and high temperature X-ray Guinier camera. Phase transitions of kalsilite are summerized and discussed.

• New & Renewable Energy
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• v.18 no.1
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• pp.29-34
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• 2022

The most prevalent cause of solar cell efficiency loss is reduced recombination at the metal electrode and silicon junction. To boost efficiency, a a SiO_X/poly-Si passivating interface is being developed. Poly-Si for passivating contact is formed by various deposition methods (sputtering, PECVD, LPCVD, HWCVD) where the ploy-Si characterization depends on the deposition method. The sputtering process forms a dense Si film at a low deposition rate of 2.6 nm/min and develops a low passivation characteristic of 690 mV. The PECVD process offers a deposition rate of 28 nm/min with satisfactory passivation characteristics. The LPCVD process is the slowest with a deposition rate of 1.4 nm/min, and can prevent blistering if deposited at high temperatures. The HWCVD process has the fastest deposition rate at 150 nm/min with excellent passivation characteristics. However, the uniformity of the deposited film decreases as the area increases. Also, the best passivation characteristics are obtained at high doping. Thus, it is necessary to optimize the doping process depending on the deposition method.

• Journal of the Korean Ceramic Society
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• v.20 no.1
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• pp.25-30
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• 1983

This experiment was studied in the system of (1-x) CaO MgO $2SiO-Al_2O_3$ to investigate forming of solid solution. The technique empolyed was the well known water-quenching method. Differential thermal analysis of the each glass water quenched indicated that under 30 mole% $Al_2O_3$ was lowered with increasing of the amount of $Al_2O_3$ It was supposed by X-ray diffraction patterns of each specimen sintered at various temperature that only solid solution was formed under the 30mole % $Al_2O_3$ compositions solid solution and anorthite were formed at the 20mole% $Al_2O_3$ composition anorthite solid solution and spinel$(MgAl_2O_4)$ were formed over the 40mole% $Al_2O_3$ compositions. The maximum density and thermal expanison coefficient was 2.89g/cm 7.74x106./C$^{\circ}$ respectively in the composi-tion of 10 mole% $Al_2O_3$ . All the specimens showed linear thermal expansion behavior. Microhardness was as high as 850kg/nm2 in the composition of 5, 10, 20 mole % $Al_2O_3$ and dielectric constant was 7.3-6.9.

• Bulletin of the Korean Chemical Society
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• v.21 no.2
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• pp.180-186
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• 2000

• Applied Microscopy
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• v.24 no.4
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• pp.132-144
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• 1994

The application of TEM in investigating the evolution of microstructure during solid phase crystallization of the amorphous Si, $Si_{1-x}Ge_x,\;and\;Si_{1-x}Ge_x/Si$ films deposited on $SiO_2$ substrate, in identifying the failure mechanism of the TiN barrier layer in the Cu-metallization scheme, and in comparing the microstructure of the as-deposited Cu-Cr and Cu-Ti alloy films are discussed. First, it is identified that the evolution of microstructure in Si and $Si_{1-x}Ge_x$ alloy films strongly depends on the concentration of Ge in the film. Second, the failure mechanism of the TiN diffusion barrier in the Cu-metallization is the migration of the Cu into the Si substrate, which results in the formation of a dislocation along the Si {111} plane and precipitates (presumably $Cu_{3}Si$) around the dislocation. Finally, the microstructure of the as-deposited Cu-Cr and Cu-Ti alloy films is also quite different in these two cases. From these several cases, we demonstrate that the information which we obtained using TEM is critical in understanding the behavior of materials.