• Journal of the Korean Ceramic Society
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• v.31 no.6
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• pp.629-636
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• 1994

The ferrimagnetic glass-ceramics in the system Fe2O3-CaO-SiO2 for hyperthermia were investigated. Glasses could be prepared up to the content of 40 wt% of Fe2O3 and below the weight ratio of 1.0 of CaO/SiO2. The maximum saturation magnetization and the maximum coercive force were 29.85 emu/g and 340.1 Oe respectively, for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. And for a glass 40Fe2O3.30CaO.30SiO2 composition the maximum saturation magnetization and the maximum coercive force were 18.47 emu/g and 374.4 Oe heat-treated at 1,00$0^{\circ}C$ and 90$0^{\circ}C$ for 8 hours respectively. The maximum hysteresis loss was 1,726.3 cal/g for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. It was found that the ferrimagnetic Fe2O3.CaO.SiO2 glass-ceramics was little injurious to human body as results of biocompatibility test and biotoxicity test.

• Membrane Journal
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• v.14 no.4
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• pp.312-319
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• 2004

The porous SiO$_2$-B$_2$O$_3$ membrane was prepared from Si(OC$_2$$H_5$)$_4$-($CH_3$O)$_3$B-C$_2$$H_5$OH-$H_2O$ system by sol-gel method. In order to investigate the characteristics of this membrane, we examined that using BET, IR spectrophotometer, X-ray diffractometer, SEM and TEM. At $700^{\circ}C$, the surface area of SiO$_2$-B$_2$O$_3$ membrane was 354.398 $m^2$/, the median pore diameter was 0.0048 ${\mu}{\textrm}{m}$, and the particle size of SiO$_2$-B$_2$O$_3$ membrane was 7 nm. The separation properties of the gas mixture ($H_2$/$N_2$) through the SiO$_2$-B$_2$O$_3$ membrane was studied as a function of pressure. The real separation factor($\alpha$) of SiO$_2$-B$_2$O$_3$ membrane for $H_2$/$N_2$ gas mixture was 4.68 at 155.15 cmHg and $25^{\circ}C$. The real separation factor($\alpha$), head separation factor($\beta$) and tail separation factor((equation omitted)) were increased as the pressure of permeation cell increased.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.277-281
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• 2009

Superhydrophobic $SiO_2$ thin films were successfully fabricated on a glass substrate by sol-gel method. To fabricate $SiO_2$ thin film with a high roughness, $SiO_2$ nano particles were added into tetraethoxysilane (TEOS) solution. The prepared $SiO_2$ thin film without an addition of $SiO_2$ nano particles showed a very flat surface with ca. 1.27 nm of root mean square (RMS) roughness. Otherwise, the $SiO_2$ thin films fabricated by using coating solutions added $SiO_2$ nano particles of 1.0, 2.0 and 3.0 wt% showed a RMS roughness of ca. 44.10 nm, ca. 69.58 nm, ca. 80.66 nm, respectively. To modify the surfaces of $SiO_2$ thin films to hydrophobic surface, a hydrophobic treatment was carried out using a fluoroalkyltrimethoxysilane (FAS). The $SiO_2$ thin films with a high rough surface were changed from hydrophilic to hydrophobic surface after the FAS treatment. Especially, the prepared $SiO_2$ thin film with a RMS roughness of 80.66 nm showed a water contact angle of $163^{\circ}$.

• Journal of the Korean institute of surface engineering
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• v.48 no.5
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• pp.233-237
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• 2015

In order to investigate the potassium (K) gettering, Al-1%Si/$SiO_2$/PSG multilevel thin films were fabricated. Al-1%Si thin films and $SiO_2$/PSG passivations were deposited by using DC magnetron sputter techniques and APCVD (atmosphere pressure chemical vapor deposition), respectively. Heat treatment was carried out at $300^{\circ}C$ for 5 h in air. SIMS (secondary ion mass spectrometry) depth profiling analysis was used to determine the distribution of K, Al, Si, P, and other elements throughout the $SiO_2$/PSG passivated Al-1%Si thin film interconnections. Potassium peaks were observed throughout the $SiO_2$/PSG passivation layers, and especially the interface gettering at the $SiO_2$/PSG and at the Al-1%Si/$SiO_2$ interfaces was observed. Potassium gettering in Al-1%Si/$SiO_2$/PSG multilevel thin films is considered to be caused by a segregation type of gettering.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.197-201
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• 2004

SiO$_2$ and SiON thick films were deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique on silicon wafer (100) using SiH$_4$ and $N_2$O as precursor gases. In this work, the influence of rf power, and rf bias power on the optical and physical properties of SiO$_2$ and SiON thick films is presented. The refractive index decreases with increasing rf power, and rf bias power. The refractive index of the films varied from 1.4493 to 1.4952 at wavelength at 1552 nm, with increasing rf power, the nitrogen content decreases while the oxygen content increases, in a manner that the O/N ratio increases approximately linearly.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.4
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• pp.25-29
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• 2008

Reliability and performance in metal gate/high-k device with multiple gate dielectrics were investigated. MOSFETs with a thin $HfSiO_x$ layer on a thermal Si02 dielectric as gate dielectrics exhibit excellent mobility and low interface trap density. However, the distribution of threshold voltages of $HfSiO_x/SiO_2$ stack devices were wider than those of $SiO_2$ and $HfSiO_x$ single layer devices due to the penetration of Hf and/or intermixing of $HfSiO_x$ with underlying $SiO_2$. The results of TZDB and SILC characteristics suggested that a certain portion of $HfSiO_x$ layer reacted with the underlying thick $SiO_2$ layer, which in turn affected the reliability characteristics.

• Journal of the Korean Ceramic Society
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• v.29 no.6
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• pp.431-440
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• 1992

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.18-19
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• 2002

Si 웨이퍼제조 시 나오는 페슬러지에서 SiC 연마재와 절삭유를 분리해내면 Si 분말을 얻을 수 있다. 본 연구에서의 SiC는 폐슬러지 Si 분말에 C 분말을 혼합하여 제조할 수 있다. Si-C-O 3성분계는 Si, $SiO_2$, SiC, C 4개의 응축상과 CO, SiO, $CO_2$, $O_2$ 4개의 기체상이 가능하고 생성물들 간의 평형관계를 깁스 자유에너지에 의해 평형 반응식이 계산되어질 수 있다. 계산된 평형 반응식은 2개의 SiO, CO 분압이 각각 X, Y 좌표평면에 나타나는 상안정도를 그려볼 수 있다. 상안정도에서 자유도가 2인 경우는, $SiO_2$가 불안정하므로 SiC와 C가 공존하는 영역에서 온도를 독립 변수로 놓으면 나머지 독립 변수는 SiO 나 CO 기체 분압 둘 중 하나가 되어 하나의 직선으로 나타낼 수 있다. 직선을 경계로 각 응축상들의 안정영역을 하나의 좌표평면에 나타낸 후 온도에 따른 SiC의 안정영역을 알아본다.

• Journal of the Korean Ceramic Society
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• v.30 no.8
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• pp.615-622
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• 1993

In order to increase chemical durability of thin films in binary system B2O3-SiO2 and Al2O3-SiO2 on the slide glass by the dip-coating technique from TEOS(Tetraethyl Orthosilicate) and boric acid or aluminum nitrate, phosphoric acid(5~20mol%) was added, respectively. Corrosion of acid and alkali of samples treated with 1N, HCl, NaOH and distilled water at 10$0^{\circ}C$ for 15 minute, were measured IR transmittance and variance of transmittance at visible range. Surface structure of thin film was investigated with SEM and formation of crystal phase according to additiion of phosphoric acid was measrued with XRD. In Al2O3-SiO2 system, change of remarkable characteristic was not obtained at the addition of P2O5 but transmittance of thin film was decreased with addition of P2O5 in B2O3-SiO2 system.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3635-3640
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• 2013

We prepared Ni and Pd-modified $TiO_2@SiO_2$ core-shell nanostructures and then analyzed them by scanning electron microscopy, optical microscopy, X-ray diffraction crystallography, FT-IR and UV-Visible absorption spectroscopy. In addition, their CO oxidation performance was tested by temperature-programmed mass spectrometry. The CO oxidation activity showed an order of Ni-$TiO_2@SiO_2$ ($900^{\circ}C$) < Ni-$TiO_2@SiO_2$ ($90^{\circ}C$) < Ni-$TiO_2@SiO_2$ ($450^{\circ}C$) in the first CO oxidation run, and greatly improved activity in the same order in the second run. The $T_{10%}$ (the temperature at 10% CO conversion) corresponds to the CO oxidation rate of $2.8{\times}10^{-5}$ molCO $g{_{cat}}^{-1}s^{-1}$. For Ni-$TiO_2@SiO_2$ ($450^{\circ}C$), the $T_{10%}$ was observed at $365^{\circ}C$ in the first run and at $335^{\circ}C$ in the second run. For the Pd-$TiO_2@SiO_2$ ($450^{\circ}C$), the $T_{10%}$ was observed at a much lower temperature of $263^{\circ}C$ in the first CO oxidation run, and at $247^{\circ}C$ in the second run. The CO oxidation activities of transition metal modified $TiO_2@SiO_2$ core-shell nanostructures presented herein provide new insights that will be useful in developing catalysts for various environments.