• Analytical Science and Technology
• /
• v.14 no.3
• /
• pp.259-265
• /
• 2001

Photocatalytic degradation of Congo red was performed using various semiconductors as ZnO, CdS, rutile-$TiO_2$ or mixed rutile-$TiO_2$/ZnO. The change of degradation of the dye was investigated by UV-visible spectrophotometric method. The photocatalytic action of CdS was greater than ZnO and rutile-$TiO_2$ in account of low band gap energy of CdS. The rate of photocatalytic degradation reaction increased drastically in according to increasing ratio of ZnO on mixed rutile-$TiO_2$/ZnO. These photocatalytic effect of rutile-$TiO_2$ was suppressed by more stable rutile-$TiO_2$, doping the hydrolysis product with $Zn^{2+}$ prior to calcination onto the rutile-$TiO_2$ surface.

• Journal of Korean Society on Water Environment
• /
• v.35 no.6
• /
• pp.550-556
• /
• 2019

This study was carried out to improve the photocatalytic reaction of TiO₂ photocatalyst. During the photocatalytic reaction, OH radicals are generated and they have an excellent oxidation capability for wastewater treatment. To evaluate the OH radicals generated according to crystallographic structure of TiO₂ nanotubes photocatalyst, a probe compound, 4-Chlorobenzoic acid was monitored to evaluate OH radical. Ultraviolet light was applied for photocatalytic reaction of TiO₂. The 4-Chlorobenzoic acid solution was prepared at laboratory. TiO₂ nanotube was grown on titanium plate by using anodization method. The annealing temperature for TiO₂ nanotube was varied from 400 to 900 ℃ and the crystal forms of the TiO₂ nanotube was analyzed. Depending on annealing temperature, TiO₂ nanotubes have shown different crystal forms; 100% anatase (0 % rutile), 18.4 % rutile (81.6 % anatase), 36.6 % rutile (63.4 % anatase) and 98.6% rutile (1.4% anatase). As the annealing temperature increases, the rutile ratio increases. OH radical generation from 18.4 % rutile TiO₂ nanotube plate was about 3.8 times higher than before annealing and 1.4 times higher than only 100 % anatase-TiO₂ nanotube. The efficiency of the 18.4% rutile TiO₂ nanotube was the best in comparison to TiO₂ nanotube with 18.4 %, 36.6 % and 98.6 % rutile. As a result, photocatalytic ability of 18.4 % rutile-TiO₂ nanotube plate was higher than 100 % anatase-TiO₂ nanotube plate.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.31 no.4
• /
• pp.166-173
• /
• 2021

The rutile phase of TiO₂ forms a stable phase at high temperatures compared to anatase phase, but the stable temperature range of anatase changes depending on the synthesis conditions. In this study, nano-sized TiO₂ was synthesized by the Sol-gel method using TiOSO₄ and a mixed solvent of ethanol and distilled water, and the phase change of anatase and rutile according to pH and heat treatment temperature was investigated. Changes in the ratio of anatase and rutile were observed by changing the pH (3, 5, 7, 9) and heat treatment temperature (500, 600, 700, 800, 900℃) conditions of the prepared TiO₂. As a result of observing these changes through XRD and FE-SEM analysis, anatase TiO₂ at 500℃ and rutile TiO₂ at 900℃ were observed. According to the pH, at these intermediate temperatures of 600, 700 and 800℃, the ratio of anatase and rutile changes. At 700℃, it was concluded that pH = 3~5 had a larger ratio of anatase TiO₂, and pH = 7~9 had a larger ratio of rutile TiO₂.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.6
• /
• pp.640-643
• /
• 1997

Pure titanium dioxide $(TiO_2)$ films were prepared by pulsed laser deposition on a single crystal Si(100) substrate. We have investigated the growth of crystalline titanium dioxide films with respect to substrate temperature and ambient oxygen pressure. The structural properties of the films were analyzed by X-ray diffraction. We found that the anatase as well as the rutile phases could be formed from the original rutile phase of the target $TiO_2$. At 0.75 torr of ambient oxygen pressure, the structure of $TiO_2$ film was amorphous at room temperature, anatase between 300 and 600 ℃, a mixture of anatase and rutile between 700 and 800 ℃, and only rutile at 900 ℃ and above. However, at a low ambient oxygen pressure, the rutile phase became dominant; the only rutile phase was obtained at the ambient oxygen pressure of 0.01 torr and the substrate temperature of 800 ℃. Therefore, the film structures were largely influenced by substrate temperature and ambient oxygen pressure.

• Journal of the Korean Ceramic Society
• /
• v.27 no.8
• /
• pp.1050-1054
• /
• 1990

Rutile(TiO2) single crystals were grown by FZ method. Feed rod was sintered in the longitudinal tube-shaped furnace at 135$0^{\circ}C$ and optimum growth condition was growth rate 5-8mm/hr, rotation rate 30-40rpm. When crystal was growing, atomosphere was oxidized condition, and grown single crystal was annealed at 110$0^{\circ}C$. The rutile single crystals were oriented to [001] direction and color change of single crystals were related to atmosphere, and difference of electric conductivity and resistance was due to the fact above.

• Journal of Powder Materials
• /
• v.25 no.3
• /
• pp.257-262
• /
• 2018

The coupling of two semiconducting materials is an efficient method to improve photocatalytic activity via the suppression of recombination of electron-hole pairs. In particular, the coupling between two different phases of $TiO_2$, i.e., anatase and rutile, is particularly attractive for photocatalytic activity improvement of rutile $TiO_2$ because these coupled $TiO_2$ powders can retain the benefits of $TiO_2$, one of the best photocatalysts. In this study, anatase $TiO_2$ nanoparticles are synthesized and coupled on the surface of rutile $TiO_2$ powders using a microemulsion method and heat treatment. Triton X-100, as a surfactant, is used to suppress the aggregation of anatase $TiO_2$ nanoparticles and disperse anatase $TiO_2$ nanoparticles uniformly on the surface of rutile $TiO_2$ powders. Rutile $TiO_2$ powders coupled with anatase $TiO_2$ nanoparticles are successfully prepared. Additionally, we compare the photocatalytic activity of these rutile-anatase coupled $TiO_2$ powders under ultraviolet (UV) light and demonstrate that the reason for the improvement of photocatalytic activity is microstructural.

• Applied Chemistry for Engineering
• /
• v.2 no.4
• /
• pp.372-384
• /
• 1991

The sulfation of the domestic titaniferous magnetite ore with ammonium sulfate was investigated to find a cyclic process for the production of synthetic rutile and high purity iron oxide and to test the feasibility of ammonium sulfate being an alternative sulfation agent. The proper sulfation conditions were determined to be a temperature of $425^{\circ}C$, 2.5 hours of reaction time, the weight ratio of ammonium sulfate to titaniferous magnetite : 11, and particle size or titaniferous magnetite : -250 mesh. 90.4 % of $TiO_2$ and 85.3 % of iron were extracted from the titaniferous magnetite sulfated under these conditions by the water leaching. From the leachate $TiO_2$ of 93.8 % purity as a mixture of rutile and anatase and ${\alpha}-Fe_2O_3$ of 97.6 % purity were obtained.

• Journal of the Korean Chemical Society
• /
• v.49 no.6
• /
• pp.567-574
• /
• 2005

• Journal of the Korean Ceramic Society
• /
• v.48 no.2
• /
• pp.178-182
• /
• 2011

The Rutile - type brown pigments doped with chromium were synthesized. Samples of $Ti_{1-x}Cr_xO_2$ ($0.02{\leq}X{\leq}0.08$) were synthesized by the solid state method. Solid solution limit of Cr contents to the rutile structure and its coloration were studied. Optimum composition was investigated accordingly. The characteristics of synthesized pigments were analyzed by XRD, SEM, Raman spectroscopy and UV. As a result, single phase of Rutile was observed from $1000^{\circ}C$ by XRD. The maximum limit of solid solution was 0.06 mole $Cr_2O_3$. The glazed sample showed brown color, and the value of CIE $L^*a^*b^*$ was $L^*$ 33.27, $a^*$ 10.64, $b^*$ 20.84.

• Korean Journal of Materials Research
• /
• v.6 no.12
• /
• pp.1213-1220
• /
• 1996

산소분압과 온도변화에 따라 비양론성 rutile(TiO2-x)의 결함모델을 전기전도 측정법에 의해 연구하였다. 산소분압과 전기전도도의 상관관계에 의하면, rutile에서 주결함은 2가로 하전된 산소빈자리와 4가로 하전된 침입형 티타늄이온이다. 117$0^{\circ}C$이상의 온도에서는 침입형 Tii…이온이 지배적인 결함이었으나, 117$0^{\circ}C$이하의 낮은 산소분압대에서는 2가로 하전된 산소빈자리가 주된 결함이었다. rutile의 전기전도 실험에서 제안된 결함모델은 본 연구팀이 O18추적자 확산실험에 의해 제안하였던 결과치와 일치하였다.