• 한국세라믹학회지
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• 제24권4호
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• pp.397-403
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• 1987

Pb(Zr0.52Ti0.48)O3 powders were prepared by hydrothermal synthesis. Using soluble salts such as Pb(NO3)2, TiCl4 and ZrOCl2$.$8H2O and oxide such as PbO and TiO2 as starting materials, PZT powder was hydrothermally synthesized at the temperature range between 150$^{\circ}C$ and 200$^{\circ}C$. The result showed that reactivity by alkali was decreased in the sequence of Pb(NO3)2, TiCl4, ZrOCl2, PbO, TiO2 and ZrO2. Using the first three soluble salts, PZT powder was synthesiged at 150$^{\circ}C$ for 1hr. In PbO-TiCl4-ZrOCl2 system, PZT powder was synthesized at 150$^{\circ}C$ for 8rs. In Pb(NO3)2-TiO2-ZrOCl2 system, PZT powder was synthesized at 150$^{\circ}C$ for 16hrs, in PbO-TiO2-ZrOCl2 system, the powder was synthesized at 200$^{\circ}C$ for 8hrs.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권2호
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• pp.8-14
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• 2016

We compared the plausible reaction mechanism and quantitative efficiency of highly self-organized TiO₂ nanotube (ntTiO₂) film with TiO₂ powder. Film was fabricated by electrochemical potentiostatic anodization of titanium thin film in an ethylene-glycol electrolyte solution containing 0.3 wt% NH₄F and 2 vol% deionized water. Nanotubes with a pore size of 80-100 nm were formed by anodization at 60 V for 3 h. Humic acid (HA) was degraded through photocatalytic degradation using the ntTiO₂ film. Pseudo first-order rate constants for 0.3 g of ntTiO₂, 0.3 g TiO₂ powder, and 1 g TiO₂ powder were 0.081 min⁻¹, 0.003 min⁻¹, and 0.044 min⁻¹, respectively. HA adsorption on the ntTiO₂ film was minimal while adsorption on the TiO₂ powder was about 20% based on thermogravimetric analysis. Approximately five-fold more normalized OH radicals were generated by the ntTiO₂ film than the TiO₂ powder. These quantitative findings explain why ntTiO₂ film showed superior photocatalytic performance to TiO₂ powder.

• 공업화학
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• 제19권3호
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• pp.270-276
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• 2008

$TiO_2$의 가장 큰 특징은 광촉매적 특성을 들 수 있으나 순수한 $TiO_2$는 자외선 영역에서만 활성을 보이는 단점이 있다. 단점을 보완하고자 본 연구에서는 초고온, 고활성을 이용한 열플라즈마 공정으로 질소가 도핑된 $TiO_2$를 합성하여 $TiO_2$의 광촉매적 특성을 높이고자 하였다. 직류 플라즈마 제트를 이용하여 비금속이온인 질소와 반응 가스인 산소를 $TiCl_4$와 함께 플라즈마 반응기 안에서 반응시켜 질소가 도핑된 $TiO_2$ 나노 분말을 합성하였다. 합성 조건으로 질소의 유량을 변화하였다. 합성 변수에 따른 입자의 상조성, 크기를 분석하였고 아세트알데히드와 곰팡이를 광분해하는 실험을 통해 광촉매 활성을 살펴보았다. 한편 $TiO_2$의 분말 상태와 코팅된 상태의 광촉매 특성을 비교하고자 합성한 분말의 스핀 코팅과 PLD (Pulsed Laser Deposition)을 통해 $TiO_2$를 코팅하였다. 아세트알데히드 분해 실험의 결과 질소가 도핑된 $TiO_2$ 분말의 경우가 순수한 $TiO_2$ 분말에 비해 가시영역에서의 광촉매 활성이 두 배 이상 뛰어난 것을 확인하였으며, 곰팡이 분해 실험 결과 역시 질소가 도핑된 $TiO_2$ 분말에 곰팡이가 분해되는 것을 확인하였다. 분말과 필름을 제조하여 메틸렌블루 광분해 실험한 결과 분말의 경우 100% $TiO_2$입자가 메틸렌블루 분해에 이용되며, 반면 스핀 코팅의 경우 바인더의 함량 때문에 20~30%의 $TiO_2$만이 분해에 이용되기 때문에, 분말의 경우 초기 30 mL 메틸렌블루를 한번에 분해할 수 있었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1097-1098
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• 2006

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. Silica coated $BaTiO_3$ powders were prepared by sol-gel method. The particle size of the $BaTiO_3$ powders were $\sim35$ nm and the thickness of the $SiO_2$ coating layer was $\sim5$ nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion. The Zeta potential of $SiO_2$ coated $BaTiO_3$ was getting close to that of pure silica with a more negative charge, compared with that of the uncoated $BaTiO_3$. The onset temperature of shrinkage curves shifted to higher temperatures with increasing $SiO_2$ contents

• 한국분말재료학회지
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• 제25권1호
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• pp.48-53
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• 2018

One-dimensional rutile $TiO_2$ is an important inorganic compound with applicability in sensors, solar cells, and Li-based batteries. However, conventional synthesis methods for $TiO_2$ nanowires are complicated and entail risks of environmental contamination. In this work, we report the growth of $TiO_2$ nanowires on a Ti alloy powder (Ti-6wt%Al-4wt%V, Ti64) using simple thermal oxidation under a limited supply of $O_2$. The optimum condition for $TiO_2$ nanowire synthesis is studied for variables including temperature, time, and pressure. $TiO_2$ nanowires of ${\sim}5{\mu}m$ in length and 100 nm in thickness are richly synthesized under the optimum condition with single-crystalline rutile phases. The formation of $TiO_2$ nanowires is greatly influenced by synthesis temperature and pressure. The synthesized $TiO_2$ nanowires are characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM).

• 전기학회논문지
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• 제57권9호
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• pp.1599-1605
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• 2008

The research was conducted in order to improve the hydrogen generation efficiency of the electrical plasma technology from tap water by using $TiO_2$ photocatalyst, mixed Cu - $TiO_2$ powder, and mixed Ni - $TiO_2$ powder as the catalysts. Experiments were performed with the pulsed power and nitrogen carrier gas. The result has shown that the hydrogen concentration with the presence of $TiO_2$ powder was created higher than that of without using photocatalyst. The hydrogen concentration with using $TiO_2$ was 3012ppm corresponding to the applied voltage of 16kV, while it without using the $TiO_2$ was 1464ppm at the same condition . The effect of $TiO_2$ powder was strongly detected at the applied voltages of 15kV and 16kV. This phenomena might be resulted from the co-effect of the pulsed power discharge and the activated state of $TiO_2$ photocatalyst. The co-effect of the mixed catalysts such as Cu-$TiO_2$ and Ni-$TiO_2$ (the mixed photocatalyst $TiO_2$ and transition metals) were also investigated. The experimental results showed that, Cu and Ni powder dopants were greatly enhancing the activity of the $TiO_2$ photocatalyst. Under these experimental conditions the extremely high hydrogen concentrations at the optimal point were produced as 4089ppm and 6630ppm, respectively.

• 한국분말재료학회지
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• 제19권4호
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• pp.310-316
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• 2012

Nanocrystalline $BaTiO_3$ powder could be synthesized by solid-state reaction using the mixture which was prepared by a high energy milling process in a bead mill for $BaCO_3$ and nanocrystalline $TiO_2$ powders mixture. Effect of the milling time on the powder characteristic of the synthesized $BaTiO_3$ powder was investigated. Nanocrystalline $BaTiO_3$ with a particle size of 50 nm was obtained at $800^{\circ}C$. High tetragonal $BaTiO_3$ powder with a tetragonality(=c/a) of 1.009 and a specific surface area of $7.6m^2/g$ was acquired after heat-treatment at $950^{\circ}C$ for 2 h. High energy ball milling was effective in decreasing the reaction temperature and increasing the tetragonality.

• 한국응용과학기술학회지
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• 제24권1호
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• pp.1-9
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• 2007

It prepared the $TiO_2$ powder which has photo-catalytic activity in the visible-light by the wet process with titanium oxysulfate. The titanium $dioxide(TiO_2)$ by the wet process creates a new absorption band in the visible light region, and is expected to create photocatalytic activity in this region. Anatase $TiO_2$ powder which has photocatalytic activity in the visible light region, is treated using microwave and radio-frequency(RF) plasma. But, the $TiO_2$ powder for the visible light region, which also can be easily produced by wet process. The wet process $TiO_2$ absorbed visible light between 400nm and 600nm, and showed a high activity in this region, as measured by the oxidation removal of aceton from the gas phase. The AH-380 sample appears the yellow color to be strong, the catalytic activity in the visible ray was excellent in comparison with the plasma-treated $TiO_2$. The AH-380 $TiO_2$ powder, which can be easily produced on a large scale, is expected to have higher efficiency in utilizing solar energy than the plasma-treated $TiO_2$ powder.

• 한국결정성장학회지
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• 제12권2호
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• pp.91-95
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• 2002

Titannium tetra-isoporpoxide의 가수분해 반응을 이용하여 nanosize의 $TiO_2$powder를 합성하고, 가수분해 반응에 있어서 촉매로 사용되는 HCI과 $NH_4$OH의 첨가량에 따른 반응양상과 생성된 $TiO_2$분말의 특성의 변화를 조사하였다. 염기성 촉매인 $NH_4$OH,를 사용하였을 경우에 균질한 형상의 powder 형태의 $TiO_2$를 합성할 수 있었으며, 산성 촉매인 HCI을 사 용하여 p보가 5.04 이하일 경우에는 괴상이나 과립의 형태로 생성되었다. 사용한 촉매의 종류와 양에 따라 저온의 결정상인 anatase의 생성속도와 보다 안정한 rutile상으로의 상전이 속도가 영향을 받았다.

• 한국분말재료학회지
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• 제11권1호
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• pp.28-33
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• 2004

In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of $TiO_2$ and $CoTiO_3$. This oxide powder was transformed to a mixed state of titanium car-bide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of $CoTiO_3$ to $TiO_2$ and Co, reduction of $TiO_2$, to the magneli phase($Ti_nO_{2n-1}$, n>3), reduction of the mag-neli phase($Ti_nO_{2n-1}$, n>3) to the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases, and reduction and carburization of the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases to titanium carbide.