• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.561-564
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• 2006

$SnO_{2}$-doped anatase type $TiO_{2}$ powder was prepared by the polymerization complex route from tin(IV) bis (acetylacetonate) dichloride, titanium diisopropoxide bis (acetylacetonate) and polyethylene glycol (PEG) as a complexing agent. The structural changes of reaction mixture were monitored by fourier transform infarared (FT-IR) spectroscopy. The microstructure and morphology of gel powder were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD). The photocatalytic activity of these powders with the anatase structure was investigated by using indigo carmine solution.

• Journal of the Korean Ceramic Society
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• v.36 no.11
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• pp.1211-1216
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• 1999

TiO2 thin films were prepared by reactive magnetron sputtering on glass substrate and subjected into investigation about their hydrophilic properties. Varing Ar/O2 ration and post annealing at 50$0^{\circ}C$ for 12h anatase and rutile phases of TiO2 films were obtained. Hydrophilic properties were evaluated by determination of contact angle of water droplet on TiO2 surface. On as-annealed TiO2 films water droplet spreaded widely with ~0$^{\circ}$contact angle. Sonication(60 Hz, 28kHz 40kHz) and following dark room treatments turned these hydrophilic TiO2 films into hydrophobic state. All of hydrophobic films were converted recersibly into their original state after UV illumination. Hydrophobic states of anatase films were saturated after sonication and remain same during dark room treatment. But it was found that the conversion into hydrophobic state of rutile films progressed. further after sonication. Therefore it was concluded that Ti3+/Ti+4 ratio is the key to determine hydrophilicity of TiO2 surface so that different surface structure of polymorphs could lead to unique characteristics.

• Carbon letters
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• v.8 no.3
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• pp.177-183
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• 2007

[ $TiO_2$ ]ACF composites were prepared by the electrochemical method with Titanium (IV) n-butoxide (TNB) electrolyte under different electrochemical operation time. The BET surface area for $TiO_2$/ACF composites decrease with the increase of electrochemical operation time. There is a single crystal structure which is anatase in all of the samples from the data of XRD. The SEM micrphotographs of $TiO_2$/ACF composites show that the $TiO_2$ particles were well mixed with the ACF. There are O and P with strong C and Ti peaks in all samples from EDX results, and it also shows that a decrease of the C content with a increasing of Ti content with increasing of the electrochemical operation time in the over all composites. DSC cures show that the exothermic peak of all composites at $560^{\circ}C$ represents the transformation heat of amorphous parts to anatase phase and the discontinuous grain growth of the transformed anatase particles. Finally, the excellent photoactivity of $TiO_2$/ACF composites (especially, ACFT10) could be attributed that the decrease of concentration of MB can be concluded to be much faster for the adsorption by ACF than for photocatalytic decomposition by $TiO_2$.

• Journal of Powder Materials
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• v.26 no.6
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• pp.487-492
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• 2019

Titanium dioxide (TiO₂) is a typical inorganic material that has an excellent photocatalytic property and a high refractive index. It is used in water/air purifiers, solar cells, white pigments, refractory materials, semiconductors, etc.; its demand is continuously increasing. In this study, anatase and rutile phase titanium dioxide is prepared using hydroxyl and carboxyl; the titanium complex and its mechanism are investigated. As a result of analyzing the phase transition characteristics by a heat treatment temperature using a titanium complex having a hydroxyl group and a carboxyl group, it is confirmed that the material properties were different from each other and that the anatase and rutile phase contents can be controlled. The titanium complexes prepared in this study show different characteristics from the titania-formation temperatures of the known anatase and rutile phases. It is inferred that this is due to the change of electrostatic adsorption behavior due to the complexing function of the oxygen sharing point, which crystals of the TiO₆ structure share.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.185-190
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• 2003

Titanium dioxide films were prepared by RF sputtering method on glass for various oxygen partial pressures at power 270 W. The crystal structure, photocatalytic property and the hydrophilicity of $TiO_2$thin film the deposition conditions were investigated. Crystallized anatase phase was observed in $TiO_2$film deposited at the ratio of oxygen partial pressure 10% and 20% for 2 hrs. As the increase of deposition time, the grain size and void size of $TiO_2$film have increased and also $V_2$films have been good crystallinity. The ultraviolet-visible light absorption of $TiO_2$films was increased with increasing of deposition time and occured chiefly at the wavelength between 280 and 340 nm. The absorption band was shifted to a longer wave length as deposition time increased. Water contact angle on the X$TiO_2$film of anatase structure was decreased with increasing ultraviolet illumination time and became lower than $11^{\circ}$ from $83^{\circ}$. When hydrophilic $TiO_2$film changed by enough ultraviolet illumination was stored in the dark, the film surface gradually turned to hydrophobic state.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.9 s.240
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• pp.1013-1021
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• 2005

In this work, $TiO_2$ nanoparticles were synthesized using a N2-diluted hydrogen coflow diffusion flame. The effects of flame temperature on the crystalline structure and the size of formed nanoparticles were investigated. The maximum centerline temperature of the flame ranged from 1,920K for $H_2-only$ flame to 863k for $81\%\;N_2-diluted$ flame. The morphology and the crystal structure of $TiO_2$ nanoparticles were analyzed by a TEM and a XRD, respectively. The particle size distribution was also measured by using a scanning mobility particle size. (SMPS). The mean particle diameter was calculated from the TEM images depended on the flame temperature, having minimum at about 1,look. Based on the SMPS measurements, the mean particle diameter of $TiO_2$ nanoparticles at flame temperatures > 1,300K was smaller than that at flame temperatures < 1,300K. From the XRD analysis, it was evident that the anatase fraction increased with decreasing the flame temperature. The portion of anatase phase in $TiO_2$ nanoparticles might be greater than $80\%$ when the flame temperature was lower than 1,000K.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.417-421
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• 2018

$TiO_2$ has excellent photocatalytic properties and several studies have reported the increase in its specific surface area. The structure of $TiO_2$ nanofibers indicates promising improved photocatalytic properties and these nanofibers can thus potentially be applied in air pollution sensors and pollutant removal filters. In this study, a $TiO_2$ nanofiber was fabricated by the electrospinning method. The fabrication processing factors such as the applied voltage, the distance between nozzle and collector, and the inflow rate of solution were controlled. The precursor was titanium (IV) isopropoxide and as-spun $TiO_2$ nanofibers were heated at $450^{\circ}C$ for 2 h to obtain an anatase crystalline structure. The microstructure was analyzed using field emission scanning electron microscope (FE-SEM) and X-ray diffraction analysis (XRD). The anatase phase was observed in the $TiO_2$ nanofibers after heat treatment. The diameter of $TiO_2$ nanofibers increased with the flow rate, but decreased with decreasing applied voltage and nozzle to collector distance. The diameter of $TiO_2$ nanofibers was controlled in the range of 364 nm to 660 nm. These nanofibers are expected to be very useful in photocatalytic applications.

• Journal of Environmental Science International
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• v.17 no.2
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• pp.171-176
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• 2008

The VOCs have a direct influence on indoor air pollution, and stimulate respiratory organs and eyes in human body. Also, most of VOCs are a carcinogenic substances and causes to SBS (sickness building syndrome). Therefore, this study was progressed in photocatalysis of VOCs using UV/$TiO_2$ which was a benign process environmentally. The experiments were performed to know photodegradation characteristics as crystalline structure of $TiO_2$ which had anatase, rutile and P-25 (anatase : rutile = 70 : 30). The main purpose of this study was to identify photocatalytic characteristics as inlet concentration of reactants, $H_2O$, and residence time.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1347-1352
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• 2004

In this work, $TiO_{2}$ nanoparticles were synthesized using a $N_{2}-diluted$ hydrogen coflow diffusion flame. The effect of flame temperature on the crystalline structure and the size of formed nanoparticles was investigated. The maximum centerline temperature of the flame ranged from 1,920K for $H_{2}-only$ flame to 863K for 81% $N_{2}-diluted$ flame. When the temperature was higher than about 1,000K, the particle size was tend to increase due to the agglomeration and sintering among the primary particles. On the other hand, when the temperature was lower than 1,000K, the portion of anatase phase was greater than 80%.

• Journal of Powder Materials
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• v.10 no.6
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• pp.448-455
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• 2003

$TiO_2$ nanopowder has been synthesized by means of the flame method using a precursor of titanium tetraisopropoxide (TTIP, Ti$(OC_3H_7)_4)$. In order to clarify the effect of cooling rate of hot flame on the formation of $TiO_2$ crystalline phases, the flame was controlled by varying the mixing ratio and the flow rate of gases. Anatase phase was predominantly synthesized under the condition having the steep cooling gradient in flame, while a slow cooling gradient enabled to form almost rutile $TiO_2$ nanopowder of above 95%.