• Journal of the Korean Ceramic Society
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• v.21 no.4
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• pp.349-354
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• 1984

The purpose of present study is to find the structure crystallization mechanism and physical properties in $TiO_2$ containing lead zinc borosilicate glass system. The experiments such as differential thermal analysis infrared spectral analysis. X-ray diffraction analysis and thermal expansion measurements have been done. Differential thermal analysis of coarse and fine glass powder showed bulk nucleating mechanism for high $TiO_2$ containing glasses and surface nucleation mechanism for low $TiO_2$ containing glasses. The prepared glasses crystallized to crystalline mixture of PbO.2ZnO. $B_2O_3$ .4PbO.2ZnO.$5B_2O_3$and 2PbO.ZnO.$B_2O_3$ when heat-treated in the range of 480 and 51$0^{\circ}C$ and crystallized to PbTiO3 when heat-treated at $600^{\circ}C$. Obtained crystalline phase of $PbTiO_3$ in glass matrix strongly affects to thermal expansion coefficient and the value of crystallized glass varied 68.0 to $107.1{\times}10-7$/$^{\circ}C$ depending on the amount of $TiO_2$added. Infrared spectral analysis showed that [$BO_3$] triangle and [$BO_3$] tetrahedral units were coexisted in the glass with high content of PbO.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.136-144
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• 1999

Crystal structures of tungsten-bronze type microwave dielectric ceramics, $BaOLa_2O_34TiO_2$ (BLT) and $BaO(Nd_{0.77}Y_{0.23})_4TiO_2$ (B(NY)T), were analysed using the Rietveld method. The most relibale refinement was obtained by refining the cation and anion positions from the x-ray and neutron diffraction data, respectively. The ambiguites inherent in the refined crystal structure by Mateeva et al. were resolved. The $BaORe_2O_34TiO_2$ structure consiste of $3\times2$ perovskite blocks and 4 pentagon-channels. The Ti-O6 octahedrons are distroted and tilted, which, consequently, induces the displacements of Ba and Re ions producing the superlattics (c$\approx$ 7.6 $\AA$). The B(NY)T showed more severely tilted Ti-O6 octahedrons. The relative dielectric constant $\varepsilon_{\gamma}$ and temperature coefficient $\tau_\varepsilon$ are 109.5 and-$180 ppm/^{\circ}C$ in BLT, 76 and $+40 ppm/^{\circ}C$ in B(NY)T, respectively. The small Re ions produced a positive $\tau_\varepsilon$. The relation between $\tau_\varepsilon$ and the octahedron tilting in complex perovskite is discussed for the tungsten bronze type structure.

• Journal of the Korean Ceramic Society
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• v.28 no.4
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• pp.305-314
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• 1991

This study was conducted to research the formation and the color development of NiO-ZnO-Fe2O3-TiO2-SnO2 system for the purpose of synthesizing the spinel pigments which are stable at high temperature. After preparing ZnO-Fe2O3 as a basic composition, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.Fe2O3 system, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.TiO2 system, and {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.SnO2 system were prepared with {{{{ chi }}=0, 0.2, 0.5, 0.7, 1 mole ratio respectively. The manufacturing was carried out at 128$0^{\circ}C$ for 30 minutes. The reflectance measurement and the X-ray analysis of these specimens were carried out and the results were summarized as follows. 1. In the specimens which included NiO, it was difficult for the spinel structure to be formed. 2. As increasing the contents of NiO and Fe2O3, all the groups which were yellow or green colored changed to brown. 3. NiO-ZnO-Fe2O3 system and NiO-ZnO-TiO2 system formed the spinel structure and the illmenite structure appeared in NiO-TiO2 system.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1586-1588
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• 2003

The Pb$(Zr{_{0.7}}Ti_{0.3})O_3$[PZT(70/30)] thin films were fabricated on Pt/$TiO_2/SiO_2$/Si substrate by RF sputtering method. The effects of Ar/$O_2$ ratio on the structural and dielectric properties of PZT thin fillms were investigated. In the case of the PZT thin films deposited with condition of 50/50$(Ar/O_2) $ ratio, the grain of the PZT thin films were fine and uniform. Increasing of $O_2$ ratio, the dielectric constant was increased. In this case the dielectirc constant and dielectric loss of PZT thin fims were about 627 and 0.010, respectively.

• Journal of the Korean Ceramic Society
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• v.41 no.7
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• pp.548-554
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• 2004

A sol-gel method was applied to coat TiO$_2$ on porous silica prepared using slurry foaming method from silica. from the results of XRD, SEM, and BET, the anatase phase was firstly observed at the coated supports with the heated of 50$0^{\circ}C$. The coated supports with the heated of $700^{\circ}C$ had the maximum anatase peak, and the particle size of coated TiO$_2$ was about 1 ${\mu}{\textrm}{m}$. Bending strength and gas permeability of the porous silica were measured for the feasibility as a catalytic supports. In case of the uncoated porous materials with the strength of 2.4 MPa, the strength increased to 3.9∼4.3 MPa after the coating process regardless of the heating temperature. On the other hand, the permeability of the uncoated porous materials decreased from 770${\times}$10$^{-13}$ $m^2$ to 363${\times}$10$^{-13}$ $m^2$ after the coating process, and it decreased with the increasing heating temperature.

• Journal of Photoscience
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• v.2 no.1
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• pp.7-11
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• 1995

Powders of artificial crystallites of titanium(IV) oxide, TiO$_2$(B), were synthesized by the calcination of tetratitanic acid (hydrate, $H_2Ti_4O_9H_2O$; TTA). The relating titanates, potassium octatitanate ($K_2Ti_8O_{17}$) and octatitanic acid($H_2Ti_8O_{17}$), were also prepared. These powders, loaded with small amount of Pt, were suspended in an aqueous solution of 2-propanol and irradiated under argon atmosphere at 298 K + 0.5 deg. All the photocatalysts tested in this study produced almost equimolar amount of acetone and molecular hydrogen (H$_2$). Among them TiO$_2$(B) and TYA showed the higher photocatalytic activity but rather lower than commercial titanium(IV) oxide (TiO$_2$) powders. The photocatalytic activity of TiO$_2$(B) for 2-propanol dehydrogenation in deaerated aqueous suspension increased with the elevating calcination temperature. Comparison of rate of H$_2$ formation from methanol and 2-propanol solutions by the TiO$_2$(B) photocatalyst suggested a possibility of selection of substrate with its molecular size by TiO$_2$(B)

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.222-228
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• 1993

In order to obtian TiO2 fine powder of high purity, the new method which is different from the sulfate process and the chloride one was employed. TiO2 was syntehsized by the reaction between elemental titanium particles and H2O2 solutiosn at 30~7$0^{\circ}C$, and then TiO2 powder was characterized using XRD, SEM, TEM, DTA and FT-IR. It was found that the initial reaction rate was fast at a high temperature due to the high generation of activated oxygen associated with thedecomposition of H2O2. However, the reaction was slowly proceeded at a low temperature due to slow decomposition of H2O2. In this experimental range, the optimum temeprature was ocnsidered to be about 5$0^{\circ}C$. The primary particles of the hydrous titanium dioxide (TiO2 gel) before aging were spherical, and their mean sizes were about 50nm. The similar shapes and sizes were observed with calcinatin at 40$0^{\circ}C$. The FT-IR spectrum of Ti-OH in the TiO2 gel powder appeared at around 3380cm-1, 1630cm-1 and 530cm-1. This gel powder was crystallized into the anatase type TiO2 at 300~40$0^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.625-631
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• 2000

In this study, the characteristics and sinterablities of TiO2 powders which were fabricated on sol-gel process and supercritical fluid process were examined. The powders fabricated on sol-gel process were amorphous. The particle size and shape were changed with the amount of water used for hydrolysis of titanium ethoxide. The powders were changed from amorphous to crystalline by heating at 400℃. The crystalline anatase TiO2 powders were directly prepared in ethanol supercritical fluid condition that temperature was 270±3℃ and pressure was 7.3 MPa. It's primary crystalline size was 20 nm and agglomerated as spherical shape whose size was 0.7∼1㎛. The powders prepared on sol-gel process were not sintered densely at 900℃ because of abnormal grain growth. However, the powders which prepared on supercritical fluid process were sintered densely at the comparatively low temperature of 800℃ by ideal growth of grain, which are fired at 900℃.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2A
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• pp.129-136
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• 2011

Recently studies on functional concrete with a photocatalytic material such as $TiO_2$ have actively been carried out in order to remove air pollutants. The absorbtion of $TiO_2$ from those studies is applied by it being directly mixed into concrete or by suspension coated on the surface. When it comes to the effectiveness, the former process is less than that of the latter compared with the $TiO_2$ use. As a result, the direct coating of $TiO_2$ on materials' surface is more used for effectiveness. The Surface spread of it needs to have a more than $400^{\circ}C$ heat treat done to stimulate the activation and adhesion of photocatalysis. Heat treat consequently leads hydration products in concrete to be dehydrated and shrunk and is the cause of cracking. The study produces $TiO_2$ used Sol-gel method which enables it to be coated with a low temperature treat, applies it to pearlite using Lightweight Aggregate Concrete fixed with a low temperature treat and evaluates the spread performance of it. In addition to this, the size of pearlite is divided into two types: One is 2.5 mm to 5.0 mm and the other is more than 5.0 mm for the benefit of finding out the removal characteristics of $CH_3CHO$ whether they are affected by pearlite size, mixing method and ratio with $TiO_2$ and elapsed time. The result of this experiment shows that although $TiO_2$ produced by Sol-gel method is treated with 120 temperature, it maintains a high spread rate on the XRF(X ray Florescence) quantitative analysis which ranks $TiO_2$ 38 percent, $SiO_2$ 29 percent and CaO 18 percent. In the size of perlite from 2.5 mm to 5.0 mm, the removal characteristic of $CH_3CHO$ from a low temperature heated Lightweight concrete appears 20 percent higher when $TiO_2$ with Sol-gel method is spreaded on the 7 percent of surface. In other words, the removal rate is 94 percent compared with the 72 percent where $TiO_2$ is mixed in 10 percent surface. In more than 5.0 mm sized perlite, the removal rate of $CH_3CHO$, when $TiO_2$ is mixed with 10 percent, is 69 percent, which is similar with that of the previous case. It suggests that the size of pearlite has little effects on the removal rate of $CH_3CHO$. In terms of Elapsed time, the removal characteristic seems apparent at the early stage, where the average removal rate for the first 10 hours takes up 84 percent compared with that of 20 hours.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.37-42
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• 2000

The comparative study of texture of Al/Ti thin films deposited on low-dielectric polymer and $SiO_2$substrates has been investigated. Fifty-nm-thick Ti films and 500-nm-thick Al-1%Si-0.5%Cu (wt%) films were deposited sequentially onto low-k polymers and $SiO_2$by using a DC magnetron sputtering system. The texture of Al thin film was determined using X-ray diffraction (XRD) theta-2theta ($\theta$-2$\theta$) and rocking curve and the microstructure of Al/Ti films on low-k polymer and $SiO_2$substrates was characterized by cross-sectional transmission electron microscopy (TEM). Both the $\theta$-2$\theta$ method and rocking curve measurement suggest that Al/Ti thin films deposited on $SiO_2$have stronger texture than those deposited on low-k polymer. The texture of Al thin films strongly depended on that of Ti films. Cross-sectional TEM revealed that grains of Ti films on $SiO_2$substrates had grown perpendicular to the substrate, while the grains of Ti alms on SiLK substrates were formed randomly. The lower degree of (111) texture of Al thin films on low-k polymer was due to Ti underlayer.