• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.798-800
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• 1998

(Ba,Sr)$TiO_3$ thin films were etched with $Cl_2$/Ar gas mixing ratio in an inductively coupled plasma (ICP) by varying the etching parameter such as f power, do bias voltage, and chamber pressure. The etch rate was $560{\AA}/min$ under Cl_2/(Cl_2+Ar)$ gas mixing ratio of 0.2, rf power of 600 W, do bias voltage of 250 V, and chamber pressure of 5 mTorr, At this time, the selectivity of BST to Pt, $SiO_2$ was respectively 0.52, 0.43. The surface reaction of the etched (Ba,Sr)$TiO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS).

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.613-619
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• 2007

This study has carried out a performance of dimensionally stable anode for the purpose of disinfection of Legionella pneumophila in water. Three kinds of electrode were prepared by plating and thermal deposition, which were coated by the oxides of Pt, Ru and Ir on Ti metal surface, respectively. The order of disinfection performance for Legionella pneumophila was Ru/Ti > Ir/Ti > Pt/Ti. Free Cl and $ClO_2$ generation of Ir/Ti electrode was higher than that of two electrodes. However, the concentrations of generated $H_2O_2$ and $O_3$ of the Ru/Ti electrode were highest among the three electrodes. The higher NaCl concentration was, the more oxidants was generated and disinfection effect was increased. However, optimum NaCl dosage was 0.0125% due to the regulation on the conductivity and $Cl^-$ concentration for the cooling water quality of air conditioning and refrigeration equipment. With the increase of current, oxidants was more generated and following disinfection effect was increased. The increase of electrode distance reduced oxidants generation due to the low electric power, and their disinfection effect was decreased accordingly.

• Resources Recycling
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• v.29 no.4
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• pp.3-14
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• 2020

Titanium sponge is industrially produced by the Kroll process. In order to understand the importance of the emerging smelting and recycling process, it is necessary to review the conventional production process of titanium. Therefore this paper provides a general overview of the conventional titanium manufacturing system mainly by the Kroll process. The Kroll process can be divided into four sub-processes as follows: (1) Chlorination of raw TiO₂ with coke, by the fluidized bed chlorination or molten salt chlorination (2) Magnesium reduction of TiCl₄ and vacuum distillation of MgCl₂ and Mg by reverse U-type or I-type with reduction-distillation integrated retorts (3) Electrolysis process of MgCl₂ by monopolar cells or multipolar cells to electrolyze into chlorine gas and Mg. (4) Crushing and melting process in which sponge titanium is crushed and then melted in a vacuum arc furnace or an electron beam furnace Although the apparatus and procedures have improved over the past 80 years, the Kroll process is the costly and time-consuming batch operation for the reduction of TiCl₄ and the separation of MgCl₂.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.916-924
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• 1990

The preparatin of the fine TiN powders by reduction-nitridation of TiCl3-Al-N2 system was attempted in the temperature range from 350$^{\circ}$to 100$0^{\circ}C$. The formation mechanism and kinetics of TiN were examined, and the resultant TiN powder was characterized by means of XRD, PSA and SEM-EPMA methods. TiN was formed at temperatrue higher than $600^{\circ}C$. As an intermediate phase, AlTi was obtained. The apparent activation energy for the formation of TiN was approximately 4.2kcal/mole(600$^{\circ}$~90$0^{\circ}C$). The crystallite size and lattice constnat of TiN powder obtained in the temperature range from 600$^{\circ}$to 100$0^{\circ}C$ for 2h at the Al/TiCl3 molar ratio of 1.0 were 160~255A and 4.231~4.239A, respectively. According to PSA measurement, the mean particle size ranged from 14.0 to 14.8${\mu}{\textrm}{m}$.

• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.1023-1028
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• 1993

To obtain a single phase of Ba2Ti9O20 at lower temperature than previious other researches. We investigated the effect of Zr substitution for predetermined portions of Ti in Ba2Ti9O20. In this study, the four compounds(x=0, 0.028, 0.048, 0.068) of Ba2(Ti1-xZrx)9O20 were prepared by coprecipitation reaction of BaCl2, TiCl4 and ZrOCl2 with (NH4)2CO3 and NH4OH as the coprecipitating agents and pH regulators, in queous solution. Owing to 4.8 mol% addition, the single phase of Ba2Ti9O20 showing high Q was obtained at 115$0^{\circ}C$ which is lower by 25$0^{\circ}C$ than the temperature in case of mechanical mixtures of BaCO3 and TiO2.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.168-168
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• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.223-230
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• 2002

Pure titanium and Ti6Al4V alloy have been mainly used as implant materials but the cytotoxicity of V, neurotoxicity of Al resulting in Alzheimer disease had been reported. This paper was described the influence of composition of Ti-Nb alloys with 3 wt%Nb, 20 wt%Nb on the microstructure and corrosion resistance. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at $1000^{\circ}C$ for 24hr. The alloys were rolled in $\beta$ and ${\alpha}+{\beta}$ regions. The corrosion resistance of Ti alloys were evaluated by potentiodymic polarization test in 0.9% NaCl and 5% HCl solutions. The results can be summarized as follows: 1. The microstructure was transformed from $\alpha$ phase to ${\alpha}+{\beta}$ phase by adding Nb 2. The hardness of Ti-20Nb alloy was greater than Cp- Ti, Ti-3Nb alloy. 3. The corrosion resistance of Ti-20Nb alloy was better than that of Cp-Ti, Ti-3Nb alloy in 0.9%NaCl and 5%HCl solutions.

• Journal of the Korean Ceramic Society
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• v.23 no.6
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• pp.33-36
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• 1986

The $PbTiO_3$is well known materials having remarkable ferroelectric piezoelectric and pyro-electric properties. Thin films of the lead titanite has been successfully fabricated by Chemical Vapor Deposition on the borosilicate glass and titanium substrate. The $PbTiO_3$ thin film deposited on the borosilicate glass using the $PbCl_2$, $TiCl_4$ dry oxygen and wet oxygen at different temperatures (50$0^{\circ}C$-$700^{\circ}C$) grows along the (001) preferred orientation. On the other hand the $PbTiO_3$ thin film deposited on the titanium substrate using the PbO grows along the (101) preferred orientation. Growth orientation of deposited $PbTiO_3$ depends on the reaction species irrespective of substrate materials. Maximum dielectic constant and loss tangent of the $PbTiO_3$ thin film deposited on the titanium substrate are about 90 and 0.02 respectively, . Deposition rates of $PbTiO_3$ deposited on the borosilicate glass and titanium substrate are 10-15 ${\mu}{\textrm}{m}$/hr. Titanium dioxide interlayer formed be-tween $PbTiO_3$ film and titanium substrate material, It improved the adhesion of the film.

• Journal of the Korean Chemical Society
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• v.37 no.7
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• pp.689-691
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• 1993

• Journal of the Korean Ceramic Society
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• v.21 no.3
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• pp.278-282
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• 1984

Barium titanate powder was made by firing the complex hydroxide which had been synthesized with chemical wet process by the medium of $H_2O_2$. This experiment was done as following A mixed solution of $BaCl_2$, $TiCl_4$ and $H_2O_2$ with 1:1:10 mol ratio was prepared. Ammonium hydroxide was added into the mixed solution. In the range of pH 8-10 $BaTiO_3$ complex hydroxide was obtained and treated at room temperature 11$0^{\circ}C$, 20$0^{\circ}C$, 40$0^{\circ}C$ and $600^{\circ}C$. The results obtaiined from this experiment were as follows. At room temperature $BaTiO_3$ complex hydroxide was amorphous. Above 10$0^{\circ}C$ crystalline $BaTiO_3$ was obtained and particle size of $BaTiO_3$ was increased with elevated temperature. So the particle size of BaTiO3 could be controlled by the firing temperature. After treating $BaTiO_3$ complex hydroxide at 10$0^{\circ}C$ the average particle size of $BaTiO_3$ was 0.22$\mu\textrm{m}$.