• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.92-95
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• 2000

The $(Sr_{1-x}Ca_x)TiO_3$(SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/$SiO_2$/Si) using RF sputtering method with substitutional contents of Ca. The maximum grain of thin films is obtained at SCT15 thin film. The dielectric constant was increased with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mol%]. The dielectric constant changes almost linearly in temperature ranges of -80~+90$[^{\circ}C]$. The temperature properties of the dielectric loss have a stable value within 0.02 independent of the substitutional contents of Ca. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200[kHz].

• Electrical & Electronic Materials
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• v.1 no.4
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• pp.319-332
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• 1988

높은 포화자속밀도와 낮은 철손을 갖는 Fe/aub 80/B$_{12}$Si$_{8}$ 비정질합금을 일반열처리, 자장열처리시켜 그의 자기적특성과 자구구조와의 관계를 조사하였다. 이를 위하여 Fe$_{80}$B$_{12}$Si$_{8}$ 비정질리본을 단롤법으로 제작하여 결정화온도를 측정하였으며 측정된 결정화온도 이하의 여러 온도에서 30분간 Ar-gas 분위기하에서 일반열처리, 자장열처리를 행하였다. 이와같이 하여 준비된 시료의 자기적특성을 조사하기 위하여 D.C., A.C. Recorking Fluxmeter를 이용하였으며 자구구조는 Bitter method로 관찰하였다. as-cast 상태의 시료를 일반열처리함에 따라 내부응력이 완화되면서 maze자구가 점차 사라지고 wave형태의 180.deg.자구가 관찰되었다. 동시에 자화과정에 있어서 자기이력곡선은 Barkhausen jump가 없어 smooth하였다. 그리고 자장열처리시에는 as-cast 상태나 일반열처리에 비해 자기적특성이 현저하게 향상되었으며 이는 열처리를 행함에 따라 내부응력이 완화되면서 maze 자구가 없어지고 일축자기 이방성으로 리본길이방향에 평행하게 형성된 180.deg.자구에 기인하는 것이라 사료된다. 그리고 자장열처리의 경우, 폭방향으로 열처리한 리본의 자구폭은 길이방향으로 열처리한 리본의 폭보다 미세하였으며 전자의 이력손실이 후자의 것보다 더 컸다.다.

• Journal of the Korean Magnetics Society
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• v.5 no.4
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• pp.261-268
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• 1995

In order to investigate the origin of the asymmetric magnetization reversal effect, we studied the variation of magnetic hysteresis loops with the alloy composition in amorphous ferromagnetic alloy ribbons of ${(Fe_{1-x}Co_{x})}_{75}Si_{10}B_{15}$ system annealed at $380^{\circ}C$ for 16 hours in a zero field condition. The asymmetric magnetization reversal effect developed more strongly in amorphous ribbons having two metallic components than in ribbons having a single metallic component. The effect developed more strongly in ribbons showing a smaller value of the saturation mag¬netostriction. The development of the asymmetric magnetization reversal effect was affected by the ratio of two metallic components as well as the magnitude of the saturation magnetostriction.

• Journal of the Korean Ceramic Society
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• v.47 no.4
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• pp.325-328
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• 2010

Varying quantities of a high-thermal-expansion glass, 50CaO-20ZnO-$20B_2O_3-10SiO_2$ (CZBS), were added to alumina and sintered at $875^{\circ}C$ for 2 h for low temperature co-firing ceramic (LTCC) applications. As the amount of glass addition increased from 40 wt% to 70 wt%, the apparent density of the sintered product increased from 88.8% to 91.5%, which was also qualitatively confirmed by microstructural observation. When the glass addition was very high, e.g., 70 wt%, an apparent formation of secondary phases such as $CaZn_2AlZnSiAlO_7$, $Ca_2Al(AlSi)O_7$, $Ca_2Al_2SiO_7$, $Ca_2ZnSi_2O_7$ and ZnO, was observed. Both the dielectric constant and the coefficient of thermal expansion increased with the glass addition, which was qualitatively consistent with the analytical models, while the experimental values were lower than the predicted ones due to the presence of pores and secondary phases.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.509-512
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• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• The Korean Journal of Ceramics
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• v.2 no.3
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• pp.125-130
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• 1996

Hematite iron ore and waste iron oxide sludge containing about 3-5 wt% $SiO_2$ were purified by three types of method developed on the basis of the Bayer process which is known as the purification process of bauxite ore. The basic principle of the developed methods lies in the fact that the impurities contained in the iron oxides, such as $SiO_2$ and $Al_2O_3$ are soluble in the alkaline reagents. Reaction of the raw materials with KOH was done in pressure vessel, at atmospheric pressure, and by both of these two. By the pressure vessel method $SiO_2$ content was reduced to below 0.5 wt% in the waste iron oxide sludge, while, in iron ore, $SiO_2$ remained at 2-3 wt%. The atmospheric pressure reaction rendered the waste iron oxide sludge $SiO_2$ content below 0.5wt% when the reaction temperature increased to above 90$0^{\circ}C$. The combined method of two previous methods was the most effective process and rendered the refined iron oxide about 300-400ppm of $SiO_2$. Using some refined iron oxides, Ba-ferrite was produced and magnetic properties were measured. The highest quality of magnetic properties obtained in this study were Br=2.09 G, bHc=1.99 KOe, iHc=4.54 KOe, $(BH)_{max}$=1.06 MGOe. Effect of sintering condition and chemical composition will be discussed.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.155-157
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• 1991

This paper describe a Laser CVD technology which realizes planarized interlevel dielectrics in sub-micron VLSI's. This technology comprises sub-micron gap filling with $SiO_2$ films between metal lines. Laser CVD process conditions have been investigated to improve step coverage of interlevel dielectrics. An ArF(193nm) Excimer Laser was used to excite and dissociate gas phase $SiH_4\;and\;N_2O$ molecules. The Laser CVD by $N_2O\;and \;SiH_4$. mixture gases has realized conformal deposition above the temperature of $300^{\circ}C$, as a result sub-micron gaps were buried with $SiO_2$ films.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.180-180
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• 2010

The design and implementation of high rate deposition process and anti-scratch property of silicon oxide film by PECVD with UHF power were investigated according to the effect of UHF input power with HF bias. New regime of high rate deposition of SiOx films by hybrid plasma process was investigated. The dissociation of OMCTS (C8H24Si4O4) precursor was controlled by plasma processes. SiOx films were deposited on polyethylene terephthalate (PET) and polycarbonate substrate by plasma enhanced chemical vapor deposition (PECVD) using OMCTS with oxygen carrier gas. As the input energy increased, the deposition rate of SiOx film increased. The plasma diagnostics were performed by optical emission spectrometry. The deposition rate was characterized by alpha-step. The mechanical properties of the coatings were examined by nano-indenter and pencil hardness, respectively. The deposition rate of the SiOx films could be controlled by the appropriate intensity of excited neutrals, ionized atoms and UHF input power with HF bias at room temperature, as well as the dissociation of OMCTS.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.242-242
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• 2012

From the combined studies of STM and synchrotron photoemission, it has been found that a $CaF_2$ molecule is dissociated to Ca and F atoms on the $Si(114)-2{\times}1$ held at $500^{\circ}C$ at the initial adsorption stage. The Ca atoms form isolated and unique shapes of silicide molecules as shown in Fig. (a), while the F atoms are desorbed from the surface. On the other hand, beyond a $CaF_2$ coverage of 0.3 monolayer, as shown in Fig. (b), in addition to these silicide molecules, a 1-D facet [composed of (113) and (115) faces] adjacent to an etch pit has been observed, and F atoms are also detected from photoemission. These results imply that F atoms act as an etchant on Si(114) and CaF is adsorbed selectively on the (113) face of this facet. From the present studies, it has been concluded that, an insulating $CaF_2$ layer like that on Si(111) cannot be formed on Si(114), but a CaF-decorated nanofacet with a high aspect-ratio can be grown.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.314-314
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• 2008

The low temperature sintering and the dielectric properties of $Al_2O_3/SiO_2$-zinc borosilicate glass composites were investigated in the view of the application for LTCC. When the sintering was conducted at $900^{\circ}C$ $ZnAl_2O_4$ and $ZnB_2O_4$ compounds formed at the $Al_2O_3$-rich and the $SiO_2$-rich compositions, respectively. The reaction between ZBS glass and $Al_2O_3/SiO_2$ caused the formation of these compounds. The $Al_2O_3/SiO_2$ ratio affected the dielectric properties. The excellent dielectric properties, i.e., Q$\times$f value= 40,000 GHz and ${\varepsilon}_r$=4.5, were obtained in the $Al_2O_3/SiO_2$-ZBS glass system and fabricated the LTCC substrate materials.