• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.381-381
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• 2009

염료감응형 태양전지의 효율 향상을 위한 다양한 방법들 중 $TiO_2$ 나노 파우더의 표면 개질 및 페이스트의 분산성 향상을 위한 연구가 활발하게 진행되고 있다. 기존 나노 파우더의 표면 개질법으로는 액상 공정인 졸겔법이 있으나 표면 처리 공정에서의 응집현상은 아직 해결해야 할 과제 중 하나이다. 이에 본 연구에서는 진공증착방법인 ALD법을 이용하여 염료감응형 태양전지용 $TiO_2$ 나노 파우더의 $SiO_2$ 산화물 표면처리를 통한 분산특성을 파악하였다. 기존 ALD법의 경우 reactor의 온도가 $300{\sim}500^{\circ}C$ 정도의 고온에서 공정이 이루어졌지만 본 실험에서는 2차 아민계촉매(pyridine)을 사용하여 reactor의 온도를 $30^{\circ}C$정도의 저온공정에서 $SiO_2$ 산화물을 코팅을 하였다. MO source로는 액체상태의 TEOS$(Si(OC_2H_5)_4)$를, 반응가스로는 $H_2O$를 사용하였고, 불활성 기체인 Ar 가스는 purge 가스로 각각 사용 하였다. ALD 공정에 의해 표면처리 된 $TiO_2$ 나노 파우더의 분산특성은 각 공정 cycle에 따라 FESEM을 통하여 입자의 형상 및 분산성을 확인하였으며 입도 분석기를 통하여 부피의 변화 및 분산 특성을 확인하였다. 공정 cycle 이 증가함에 따라 입자간의 응집현상이 개선되는 것을 확인 할 수 있었으며, 100cycles에서 응집현상이 가장 많이 감소하는 것을 확인할 수 있었다. 또한 표면 처리된 $SiO_2$ 산화막은 XRD를 통한 결정 분석 및 EDX를 통한 정성 분석을 통하여 확인하였다.

• 한국재료학회지
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• 제32권11호
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• pp.458-465
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• 2022

Interest in the use of semiconductor-based photocatalyst materials for the degradation of organic pollutants in a liquid phase has grown, due to their excellent performance and response to the light source. Herein, we fabricated a NiO-SiC-TiO₂ ternary structured photocatalyst which had reduced bandgap energy, with strong activation under UV-light irradiation. The synthesized samples were examined using XRD, SEM, EDX, TEM, DRS, EIS techniques and photocurrent measurement. The results confirmed that the two types of metal oxides were well bonded to the SiC fiber surface. The junction of the new photocatalyst exhibited a large number of photoexcited electrons and holes. The holes tended to oxidize the water and form a hydroxyl radical, which promoted the decomposition of methylene blue. The close contact between the 2D SiC fiber and metal oxide semiconductors expanded the scope of absorption wavelength, and enhanced the usability of the ternary photocatalyst for the degradation of methylene blue. Among three synthesized samples, the NiO-SiC-TiO₂ showed the best photocatalytic effect, and was considered to have excellent photoelectron transfer due to the synergy effect between the metal oxide and SiC.

• 한국결정성장학회지
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• 제8권1호
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• pp.151-159
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• 1998

자동차 모터 작동시에 사용되는 전류 제어 소자의 써미스터 조성을 개발하기 위하여 $BaTiO_3$에 첨가제로써 $Y_{2}O_{3}CaO,SiO_{2}$ 및 Mn을 선정하여 실험하였다. 0.2mol%의 $Y_{2}O_3$, 첨가에서 가장 낮은 상온 저항 16.5${\Omega}{\cdot}$cm를, 1.6mol% $SiO_2$ 첨가에서 50${\Omega}{\cdot}$cm를 보였다. 5mol%의 Ca를 Ba와 치환한 조성에서는 결정립의 크기가 34.95${\mu}$m에서 13.4${\mu}$m로 감소하였으며, 0.04mol% Mn에서 상온저항 및 ${\rho}_{max}/{\rho}_{min}$가 각각 30~40${\Omega}{\cdot}$cm, $1.5{\times}10^5$의 우수한 특성을 나타내었다.

• 한국표면공학회지
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• 제36권2호
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• pp.128-134
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• 2003

Alloys of Ti-43%Al-2%W-0.1%Si were oxidized isothermally and cyclically between $900^{\circ}C$ and$ 1050^{\circ}C$, and their oxidation characteristics were studied. During isothermal tests, the alloys oxidized slowly up to 100$0^{\circ}C$, but fast at $1050^{\circ}C$. Though the scale adherence was not good above $900^{\circ}C$, the alloys displayed better oxidation behavior than unalloyed TiAl alloys. The oxide scales consisted primarily of an outer $TiO_2$ layer, intermediate $Al_2$$O_3$-rich layer, and an inner mixed layer of (TiO$_2$ $+Al_2$$O_3$). Tungsten was present mainly at the lower part of the oxide scale, while Si over the whole oxide scale.

• 대한화장품학회지
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• 제25권4호
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• pp.43-50
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• 1999

The planarized $SiO_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but $SiO_2$ particles in this study exhibit a smooth surface structure. These single $SiO_2$ particles were used as core particles to prepare the composite particles coated with ultra fine $TiO_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited $TiO_2$ layers could be modified by adjusting the reactant concentrations, the reaction time and the temperature. The characteristics of $SiO_2/TiO_2$ composite in the field of color cosmetics are to give an UV-cut effect and to enhance the chroma of human skin color, one of optical properties.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 1999년도 IFSCC . ASCS 학술대회 발표 논문
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• pp.43-50
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• 1999

The planarized SiO$_2$ particles were prepared by two-step reduction method of making much smaller particles, micron-sized ones, to improve spreadability, adherence, and smoothness. Various pigments known as flaky extender usually have terrace layers on their surfaces, but SiO$_2$ particles in this study exhibit a smooth surface structure. These single SiO$_2$ particles were used as core particles to prepare the composite particles coated with ultra fine TiO$_2$ particles by a homogeneous precipitation method. The thickness and the morphology of the deposited TiO$_2$ layers could be modified by adjusting the reactant concentrations, the reaction time and the temperature. The characteristics of SiO$_2$/TiO$_2$ composite in the field of color cosmetics are to give an UV-cut effect and to enhance the chroma of human skin color, one of optical properties.

• 한국결정성장학회지
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• 제9권1호
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• pp.34-38
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• 1999

유기금속 화학 증착법(MOCVD)을 이용하여 Si(100) 기판 위에 $TiO_2$와 PbO의 동시 증착으로 $Pb(TMHD)_2$(PT) 박막을 증착하였다. 원료물질로는 Titanium tetra-isopropoxide(TTIP)와 $Pb(TMHD)_2$를 사용하였다. 증착온도를 $520^{\circ}C$, Pbdbfid을 30 sccm으로 고정하고, 전체유량을 750 sccm으로 하여 TTIP의 증발온도와 유량에 따른 PT 박막의 XRD 변화를 관찰하였다. PT 박막 생성은 TTIP의 증발온도 및 유량이 각각 48~$50^{\circ}C$와 18~22sccm 영역에서 생성되었으며, 생성된 박막과 기판의 계면에서는 Pb, Si, O의 상호확산을 관찰할 수 있었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.171-171
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• 2003

공정기술의 향상으로 DRAM(dynamic random acess memory)의 고집적화가 이루어지고 있으며, 각 개별소자 및 셀 영역의 점유면적의 감소가 요구되어지고 있다. 따라서 기존에 사용하던 NO (Si$_3$N$_4$/SiO$_2$)박막보다 유전율이 높은 고유전물질에 대한 연구가 진행되고 있다. Ta$_2$O$_{5}$, $Y_2$O$_3$, HfO$_2$, ZrO$_2$,Nb$_2$O$_{5}$, BaTiO$_3$, SrTiO$_3$ 및 (BaSr)TiO등이 고유전물질로 연구되고 있는데 그 중 공정의 안정성, 누설전류의 우수성으로 인해 Ta$_2$O$_{5}$이 많이 연구되고 있다. 본 실험에서는 TiO$_2$가 8 mol%가 첨가된 Ta$_2$O$_{5}$의 열처리 온도에 따른 전기적, 유전특성을 살펴보려고 한다살펴보려고 한다

• E2M - 전기 전자와 첨단 소재
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• 제11권10호
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• pp.94-99
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• 1998

Suitable replacement materials for ultrathin SiO2 in deeply scaled MOSFETs such as lattice polarizable films, which have much higherpermittivities than SiO2, have bandgaps of only 3.0 to 4.0 eV. Due to these small bandgaps, the reliability of these films as a gate insulator is a serious concern. Ramped voltage, time dependent dielectric breakdown, and hot carrier effect measurements were done on 190 layers of TiO2 which were deposited through the metal-organic chemical vapor deposition of titanium tetrakis-isopropoxide (TTIP). Measurements of the high and low frequency capacitance indicate that virtually no interface state are created during constant current injection stress. The increase in leakage upon electrical stress suggests that uncharged, near-interface states may be created in the TiO2 film near the SiO2 interfacial layer that allow a tunneling current component at low bias.

• 한국주조공학회지
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• 제22권2호
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• pp.75-81
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• 2002

The main objectives were to investigate the suitability of CaO crucible for melting TiAl alloys and to develop investment mold for investment casting of TiAl alloys. TiAl alloy specimen were prepared by plasma arc furnace under argon atmosphere. After melting of TiAl alloy using CaO crucible, the results showed that there is little contamination of oxygen in the TiAl bulk. Conventional vacuum induction furnaces can be readily adaptable to produce cast parts of TiAl without high skilled techniques. The determination of optical metallography and microhardness profiles in investment cast TiAl alloy rods has allowed the gradation of the relative thermal stability of the oxides examined. The molds used for the present study were $ZrO_2$, $Al_2O_3$, CaO stabilized $ZrO_2$ and $ZrSiO_4$. Even although high temperature of mold preheating, $Al_2O_3$ mold is a promising mold material for investment casting of TiAl alloys in terms of thermal stability, cost and handling strength. It is important to take thermal stability and preheating temperature of mold into consideration for investment casting of TiAl alloys.