• Nano
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• 제13권10호
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• pp.1850124.1-1850124.12
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• 2018

$TiO_2$ films were deposited from oxygen/titanium tetraisopropoxide (TTIP) plasmas at low temperature by Helicon-PECVD at floating potential ($V_f$) or substrate self-bias of -50 V. The influence of titanium precursor partial pressure on the morphology, nanostructure and optical properties was investigated. Low titanium partial pressure ([TTIP] < 0.013 Pa) was applied by controlling the TTIP flow rate which is introduced by its own vapor pressure, whereas higher titanium partial pressure was formed through increasing the flow rate by using a carrier gas (CG). Then the precursor partial pressures [TTIP+CG] = 0:027 Pa and 0.093 Pa were obtained. At $V_f$, all the films exhibit a columnar structure, but the degree of inhomogeneity is decreased with the precursor partial pressure. Phase transformation from anatase ([TTIP] < 0.013 Pa) to amorphous ([TTIP+CG] = 0:093 Pa) has been evidenced since the $O^+_2$ ion to neutral flux ratio in the plasma was decreased and more carbon contained in the film. However, in the case of -50 V, the related growth rate for different precursor partial pressures is slightly (~15%) decreased. The columnar morphology at [TTIP] < 0.013 Pa has been changed into a granular structure, but still homogeneous columns are observed for [TTIP+CG] = 0:027 Pa and 0.093 Pa. Rutile phase has been generated at [TTIP] < 0:013 Pa. Ellipsometry measurements were performed on the films deposited at -50 V; results show that the precursor addition from low to high levels leads to a decrease in refractive index.

• 센서학회지
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• 제32권3호
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• pp.140-146
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• 2023

Water quality is crucial for human health and the environment. Accurate measurement of the quantity of organic carbon in water is essential for water quality evaluation, identification of water pollution sources, and appropriate implementation of water treatment measures. Total organic carbon (TOC) analysis is an important tool for this purpose. Although other methods, such as chemical oxygen demand (COD) and biochemical oxygen demand (BOD) are also used to measure organic carbon in water, they have limitations that make TOC analysis a more favorable option in certain situations. For example, COD requires the use of toxic chemicals, and BOD is time-consuming and can produce inconsistent and unreliable results. In contrast, TOC analysis is rapid and reliable, providing accurate measurements of organic carbon content in water. However, common methods for TOC analysis can be complex and energy-intensive because of the use of high-temperature heaters for liquid-to-gas phase transitions and the use of acid, which present safety risks. This study focuses on a TOC analysis method using TiO₂ photocatalysis, which has several advantages over conventional TOC analysis methods, including its low cost and easy maintenance. For TiO₂, rutile and anatase powders are mixed with an inorganic binder and spray-coated onto a glass fiber substrate. The TiO₂ powder and inorganic binder solutions are adjusted to optimize the photocatalytic reaction performance. The TiO₂ photocatalysis method is a simple and low-power approach to TOC analysis, making it a promising alternative to commonly used TOC analysis methods. This study aims to contribute to the development of more efficient and cost-effective approaches for water quality analysis and management by exploring the effectiveness and reliability of the developed equipment.

• 한국염색가공학회지
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• 제25권2호
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• pp.126-133
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• 2013

Although para-aramid fibers poss higher mechanical properties, they show very low resistance to sunlight exposure. This paper studied on the effect of nano-sol coated $TiO_2$ to improve the photo-stability of p-aramid fibers. Titanium dioxides were prepared by sol-gel method from titanium iso-propoxide at different R ratio ($H_2O$/titanium iso-propoxide). All samples were characterized by XRD, TEM and UV-vis spectrometer. The mechanical properties of p-aramid fabrics by $TiO_2$ nano-sol coating before and after sunlight irradiation were measured with tensile tester. XRD pattern of titanium dioxide particles was observed by mixing phase together with rutile and anatase type. The results showed, after sunlight irradiation, the decreased mechanical properties of the fiber. Furthermore, the sunlight irradiation obviously deteriorated the surface and defected areas of the fiber severely by photo-induced chain scission and end group oxidation in air.

• 한국재료학회지
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• 제12권5호
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• pp.334-340
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• 2002

$TiO_2$-coated fly ash was synthesized by dropping method of coating agent in order to get $TiO_2$ coating layer with high photocatalytic activity on the surface of coal fly ash. The properties of the $TiO_2$ coating layer such as morphology, crystal structure, crystal size and photocatalytic activity were compared with those of the $TiO_2$-coated fly ash prepared by the traditional method of precipitation. $TiCl_4$ aqueous solution was used as a titanium stock solution and $NH_4HCO_3$ was used as a precipitant. The $TiO_2$ coating layer obtained by dropping method of coating agent was more uniform than that coated by precipitation. However, the crystal of $TiO_2$ coated by dropping method of coating agent was easy to grow by heat treatment because of the small primary particle size and bulky morphology, and its photocatalytic activity was consequently lower than that of the $TiO_2$ coated by precipitation. The $TiO_2$ coating layer obtained by both methods had a crystal structure of anatase, and the temperature of phase transformation into rutile was 90$0^{\circ}C$. The minimum crystal size of $TiO_2$ for the highest photocatalytic activity was found to be about 10nm.

• 한국재료학회지
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• 제20권8호
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• pp.429-433
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• 2010

In this study, activated carbon (AC) as a carbon source was modified with different concentrations of cobalt chloride ($CoCl_2$) to prepare a Co-AC composite, and it was used for the preparation of Co-AC/$TiO_2$ composites with titanium oxysulfate (TOS) as the titanium precursor. The physicochemical properties of the prepared Co-AC/$TiO_2$ composites were characterized by $N_2$ adsorption at 77 K, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The photocatalytic treatments of organic dyes were examined under an irradiation of visible light with different irradiation times. $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine AC, which was $389\;m^2/g$. From the XRD results, the Co-AC/$TiO_2$ composites contained a mixturephase structuresof anatase and rutile, but a cobalt oxide phase was not detected in the XRD pattern. The EDX results of the Co-AC/$TiO_2$ composites confirmed the presence of various elements, namely, C, O, Ti, and Co. Subsequently, the decomposition of methylene orange (MO, $C_{14}H_{14}N_3NaO_3S$) and rhodamine B (Rh.B, $C_{28}H_{31}ClN_2O_3$) in an aqueous solution, respectively, showed the combined effects of an adsorption effect by AC and the photo degradation effect by $TiO_2$. Especially, the Co particles in the Co-AC/$TiO_2$ composites could enhance the photo degradation behaviors of $TiO_2$ under visible light.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.417-422
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• 2010

서로 다른 관능기를 가진 카르복시산 화합물을 첨가제로 하여 과산화티탄 수용액으로부터 수열합성법으로 나노 크기의 이산화티탄을 제조하였다. 제조된 나노 크기의 이산화티탄의 물리적 성질을 조사하였으며, 이들을 사용하여 메틸렌블루의 광분해 반응에서의 활성을 조사하였다. 첨가된 카르복시산 화합물에 관계없이 아나타제형 나노 크기의 이산화티탄이 합성되었으며, 소성온도가 $700^{\circ}C$ 이상에서는 아나타제 결정구조가 루틸 결정구조로 변환되기 시작하였다. 광촉매 반응의 활성은 카르복시산의 탄소수가 커질수록 증가하였으며, 숙신산을 첨가제로 한 경우와 $500^{\circ}C$에서 소성시킨 경우에 가장 높은 활성을 보여주었다.

• 한국재료학회지
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• 제20권12호
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• pp.686-690
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• 2010

$TiO_2$ nanowires were self-catalytically synthesized on bare Si(100) substrates using metallorganic chemical vapor deposition. The nanowire formation was critically affected by growth temperature. The $TiO_2$ nanowires were grown at a high density on Si(100) at $510^{\circ}C$, which is near the complete decomposition temperature ($527^{\circ}C$) of the Ti precursor $(Ti(O-iPr)_2(dpm)_2)$. At $470^{\circ}C$, only very thin (< $0.1{\mu}m$) $TiO_2$ film was formed because the Ti precursor was not completely decomposed. When growth temperature was increased to $550^{\circ}C$ and $670^{\circ}C$, the nanowire formation was also significantly suppressed. A vaporsolid (V-S) growth mechanism excluding a liquid phase appeared to control the nanowire formation. The $TiO_2$ nanowire growth seemed to be activated by carbon, which was supplied by decomposition of the Ti precursor. The $TiO_2$ nanowire density was increased with increased growth pressure in the range of 1.2 to 10 torr. In addition, the nanowire formation was enhanced by using Au and Pt catalysts, which seem to act as catalysts for oxidation. The nanowires consisted of well-aligned ~20-30 nm size rutile and anatase nanocrystallines. This MOCVD synthesis technique is unique and efficient to self-catalytically grow $TiO_2$ nanowires, which hold significant promise for various photocatalysis and solar cell applications.

• 한국광학회지
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• 제17권3호
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• pp.296-302
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• 2006

졸-겔법으로 촉매농도에 따라 저온 $TiO_2$ 졸을 제조한 후, 침지코팅법을 이용하여 $TiO_2$ 박막을 제작하였다. 제작된 저온 $TiO_2$ 박막의 광학적, 구조적, 광활성 특성을 조사하였다. 0.10 mol, 0.25 mol, 0.50 mol과 0.75 mol의 촉매농도로 제작된 저온 $TiO_2$ 박막은 가시광 영역에서 높은 투과율 특성을 나타내었다. XRD 스펙트럼 결과에 의하면 촉매농도가 증가함에 따라 아나타제 결정구조에서 루타일 결정구조로의 상전이가 촉진되고 결정크기는 촉매농도가 증가함에 따라 아나타제 결정크기가 감소하였다. SEM 결과로부터 $TiO_2$ 박막의 표면입자크기가 0.25 mol의 측매농도에서 가장 작았다. 아나타제 결정구조를 가지는 0.10 mol, 0.25 mol과 0.50 mol의 $TiO_2$ 박막 존재 하에서 메틸렌블루가 완전히 광분해 되는 것을 확인하였다.

• 자원리싸이클링
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• 제18권4호
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• pp.24-30
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• 2009

희토류 원소를 기반으로한 알루미늄산 형광체에 담지된 산화티탄은 졸겔방법 으로 제조되었다. 이렇게 제조된 산화티탄 나노입자의 재료물성을 분석하기 위해 XRD, FT-IR, DRS UV-Vis, TEM 측정을 실시하였다. 형광체에 담지된 산화티탄 입자의 소결 전후의 XRD분석결과는 600도 이상의 온도에서 아나타제에서 루틸로 상변화가 일어나지 않았다. 600도 이상의 온도에서 지속적인(장시간) 열처리 후에도 형광체에 담지된 산화티탄이 결정화도가 높은 아나타제로 존재 하는 것은 형광체 지지체와 담지된 산화티탄의 서로 다른 결정입계에 의하여 결정성장과 상변화에 필요한 치밀화가 억제되기 때문으로 판단된다. DRS측정결과 형광체에 담지된 산화티탄은 산화티탄이 없는 형광체에 비하여 보다 긴 장파로 쉬프트한 것은 밴드갭 에너지의 환원을 나타낸다. 이러한 형광체에 담지된 산화티탄의 FT-IR 스펙트럼은 피크의 위치가 더 높은 파수로 이동하였다. 이것은 산화티탄 입자와 지지체 사이의 공유결합이 관계하기 때문 이라 판단된다. TEM 이미지는 형광체 지지체에 다른 입자 크기로 담지되어 있는 산화티탄의 분산, 결정화 및 입자 형상을 나타낸다.

• 대한치과보철학회지
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• 제45권1호
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• pp.85-97
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• 2007

Statement of problem: Recently, anodic oxidation of cp-titanium is a popular method for treatment of titanium implant surfaces. It is a relatively easy process, and the thickness, structure, composition, and the microstructure of the oxide layer can be variably modified. Moreover the biological properties of the oxide layer can be controlled. Purpose: In this study, the roughness, microstructure, crystal structure of the variously treated groups (current, voltage, frequency, electrolyte, thermal treatment) were evaluated. And the specimens were soaked in simulated body fluid (SBF) to evaluate the effects of the surface characteristics and the oxide layers on the bioactivity of the specimens which were directly related to bone formation and integration. Materials and methods: Surface treatments consisted of either anodization or anodization followed thermal treatment. Specimens were divided into seven groups, depending on their anodizing treatment conditions: constant current mode (350V for group 2), constant voltage mode (155V for group 3), 60 Hz pulse series (230V for group 4, 300V for group 5), and 1000 Hz pulse series (400V for group 6, 460V for group 7). Non-treated native surfaces were used as controls (group 1). In addition, for the purpose of evaluating the effects of thermal treatment, each group was heat treated by elevating the temperature by $5^{\circ}C$ per minute until $600^{\circ}C$ for 1 hour, and then bench cured. Using scanning electron microscope (SEM), porous oxide layers were observed on treated surfaces. The crystal structures and phases of titania were identified by thin-film x-ray diffractmeter (TF-XRD). Atomic force microscope (AFM) was used for roughness measurement (Sa, Sq). To evaluate bioactivity of modified titanium surfaces, each group was soaked in SBF for 168 hours (1 week), and then changed surface characteristics were analyzed by SEM and TF-XRD. Results: On basis of our findings, we concluded the following results. 1. Most groups showed morphologically porous structures. Except group 2, all groups showed fine to coarse convex structures, and the groups with superior quantity of oxide products showed superior morphology. 2. As a result of combined anodization and thermal treatment, there were no effects on composition of crystalline structure. But, heat treatment influenced the quantity of formation of the oxide products (rutile / anatase). 3. Roughness decreased in the order of groups 7,5,2,3,6,4,1 and there was statistical difference between group 7 and the others (p<0.05), but group 7 did not show any bioactivity within a week. 4. In groups that implanted ions (Ca/P) on the oxide layer through current and voltage control, showed superior morphology, and oxide products, but did not express any bioactivity within a week. 5. In group 3, the oxide layer was uniformly organized with rutile, with almost no titanium peak. And there were abnormally more [101] orientations of rutile crystalline structure, and bonelike apatite formation could be seen around these crystalline structures. Conclusion: As a result of control of various factors in anodization (current, voltage, frequency, electrolytes, thermal treatment), the surface morphology, micro-porosity, the 2nd phase formation, crystalline structure, thickness of the oxide layer could be modified. And even more, the bioactivity of the specimens in vitro could be induced. Thus anodic oxidation can be considered as an excellent surface treatment method that will able to not only control the physical properties but enhance the biological characteristics of the oxide layer. Furthermore, it is recommended in near future animal research to prove these results.