• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.22-24
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• 1995

The electrical conductivity of TiO$_2$doped ZnO was investigated by means of complex impedance measurement and voltage-current source and meaurement unit. The e1ectrical conductivity of TiO$_2$added ZnO was increased with increasing the concentration of TiO$_2$. The calculated relative dielectric constant was decreased with increasing the concentration of TiO$_2$. The increase of electrical conductivity seems to be the effect of TiO$_2$donor doping.

• 한국환경과학회지
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• 제15권3호
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• pp.221-227
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• 2006

Oxidative TCE decomposition over $TiO_2$-supported single and complex metal oxide catalysts has been conducted using a continuous flow type fixed-bed reactor system. Different types of commercial $TiO_2$ were used for obtaining the supported catalysts via an incipient wetness technique. Among a variety of titanias and metal oxides used, a DT51D $TiO_2\;and\;CrO_x$ would be the respective promising support and active ingredient for the oxidative TCE decomposition. The $TiO_2-based\;CrO_x$ catalyst gave a significant dependence of the catalytic activity in TCE oxidation reaction on the metal loadings. The use of high $CrO_x$ contents for preparing $CrO_x/TiO_2$ catalysts might produce $Cr_2O_3$ crystallites on the surface of $TiO_2$, thereby decreasing catalytic performance in the oxidative decomposition at low reaction temperatures. Supported $CrO_x$-based bimetallic oxide systems offered a very useful approach to lower the $CrO_x$ amounts without any loss in their catalytic activity for the catalytic TCE oxidation and to minimize the formation of Cl-containing organic products in the course of the catalytic reaction.

• 한국재료학회지
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• 제17권11호
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• pp.593-600
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• 2007

Aluminum was anodized in a $H_2SO_4$ solution, and titanium (IV) oxide ($TiO_2$) was electrodeposited into nanopores of anodic porous alumina in a mixed solution of $TiOSO_4$ and $(COOH)_2$. The photocatalytic activity of the prepared film was analyzed for photodegradation of methylene blue aqueous solution. Consequently, we found it was possible to electrodeposit $TiO_2$ onto anodic porous alumina, and synthesized it into the nanopores by hydrolysis of a titanium complex ion under AC 8-9 V when film thickness was about $15-20{\mu}m$. The photocatalytic activity of $TiO_2$-loaded anodic porous alumina ($TiO_2/Al_2O_3$) at an impressed voltage of 9 V was the highest in every condition, being about 12 times as high as sol-gel $TiO_2$ on anodic porous alumina. The results revealed that anodic porous alumina is effective as a substrate for photocatalytic film and that high-activity $TiO_2$ film can be prepared at low cost.

• 한국항해항만학회지
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• 제34권2호
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• pp.111-115
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• 2010

In this paper, the electromagnetic (EM) wave absorbers using TiO2 as a dielectric material with chlorinated polyethylene (CPE) were investigated in W-band radio frequencies. We compared the relative permittivity with reflectionless curve and the absorption properties of samples containing 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, and 80 wt.% TiO2. It is possible to realize a complex relative permittivity satisfying the reflectionless condition by choosing composition ratio of TiO2. The optimized composition ratio of TiO2 for the maximum absorption property is about 70 wt.%. As a result, we have confirmed the realization of an EM wave absorber with a high absorption property in W-band radio frequencies.

• 한국세라믹학회지
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• 제34권3호
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• pp.330-336
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• 1997

1:1 복합 페로스카이트 물질인 La(Mg1/2Ti1/2)O3 and La(Mg1/2Zr1/2)O3의 양이온 규칙 존재와 고주파 유전특성을 x선 회절과 회로망분석기를 사용하여 조사하였다. 기존의 연구에서는 두 물질 모두 양이온 규칙이 없으며 입방정 구조를 갖는다고 보고되었지만, 본 연구에서의 x선 분석에서는 양이온 규칙을 나타내는 초격자회절선과 비입방정 구조를 의미하는 기본회절선의 split이 발견되었다. 고주파 영역에서의 유전율은 La(Mg1/2Ti1/2)O3의 경우 29,La(Mg1/2Zr1/2)O3는 24, 품질계수(Q*f)는 각각 73000, 49000이다. 공진주파수 온도계수는 La(Mg1/2Ti1/2)O3의 경우 - 65ppm/$^{\circ}$C,La(Mg1/2Zr1/2)O3는 -80ppm/$^{\circ}$C로 음의 값을 가진다.

• 한국재료학회지
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• 제32권4호
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• pp.181-185
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• 2022

In this study, phase-pure titanium dioxide TiO₂ ceramics are sintered using standard high-temperature solid-state reaction technique at different temperatures (1,000, 1,100, 1,200, 1,300, 1,400 ℃). The effect of sintering temperature on the densification and impedance properties of TiO₂ ceramics is investigated. The bulk density and average grain size increase with the increase of sintering temperature. Impedance spectroscopy analysis (complex impedance Z^* and complex modulus M^*), performed in a broad frequency range from 100 Hz to 10 MHz, indicates that the TiO₂ ceramics are dielectrically heterogeneous, consisting of grains and grain boundaries. The complex impedance Z^* -plane indicates the resistance of grains of the TiO₂ ceramics increases with increasing sintering temperature, while that of grain boundaries develops in the opposing direction. The complex modulus M^*-plane shows a grain capacitance that seems to be independent of the sintering temperature, while that of the grain boundaries decreases with increasing sintering temperature. These results suggest that different sintering temperatures have effects on the microstructure, leading to changes in the impedance properties of TiO₂ ceramics.

• 한국분말재료학회지
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• 제22권6호
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• pp.396-402
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• 2015

The organic binder-free paste for dye-sensitized solar cell (DSSC) has been investigated using peroxo titanium complex. The crystal structure of $TiO_2$ nanoparticles, morphology of $TiO_2$ film and electrical properties are analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectra (EIS), and solar simulator. The synthesized $TiO_2$ nanopowders by the peroxo titanium complex at 150, 300, $400^{\circ}C$, and $450^{\circ}C$ have anatase phase and average crystal sizes are calculated to be 4.2, 13.7, 16.9, and 20.9 nm, respectively. The DSSC prepared by the peroxo titanium complex binder have higher $V_{oc}$ and lower $J_{sc}$ values than that of the organic binder. It can be attributed to improvement of sintering properties of $TCO/TiO_2$ and $TiO_2/TiO_2$ interface and to formation of agglomerate by the nanoparticles. As a result, we have investigated the organic binder-free paste and 3.178% conversion efficiency of the DSSC at $450^{\circ}C$.

• 한국세라믹학회지
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• 제23권2호
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• pp.21-30
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• 1986

Pure submicron $SrTiO_3$ powders had been synthesized with chemical wet process that $5N-NH_4OH$ solution was sprayed into the mixed solution of $SrTiO_3$, $TiCl_4$ and $H_2O_2$ with $N_2$ carrier gas. The characteristic properties of powders obtained from this experiment were as follows. The optimum synthesis condition in reaction bath was above PH 8.5 and under $25^{\circ}C$ The particle size of precipitated SrTiO(OH) powders dried at 6$0^{\circ}C$ was under 0.01${\mu}{\textrm}{m}$ and uniform. Amorphous precipitated complex powders emitted adsorbed water at 15$0^{\circ}C$ less that and crystalline $SrTiO_3$powders was produced from calcining the complex at 30$0^{\circ}C$. Sintered body of SrTiO3 fired at 133$0^{\circ}C$ showed that relative dielectric constant was 228 at 1MHZ and bulk density was 4.73g/$cm^3$.

• 한국재료학회지
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• 제5권1호
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• pp.140-148
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• 1995

Transfer matrix를 사용하여 $TiO_{2}$ 및 Ag 단일 박막과 $TiO_{2}/Ag/TiO_{2}$ 다층 박막의 두계에 따른 투과도 특성을 예측하였으며, 이를 실제 스퍼터 증착하여 제조한 박막의 광학 특성과 비교하였다. $TiO_{2}$ 및 Ag 박막에서는 복소굴절률을 사용하므로써 실제 증착박막에서 측정된 특성과 근접한 투과도 곡선의 예측이 가능하였다. $TiO_{2}/Ag/TiO_{2}$ 3층 박막의 광학 특성은 Ag의 $TiO_{2}$층으로의 확산 및 응집에 의해 transfer matrix로 예측한 투과도 특성과 전혀 다른 거동을 나타내었다. 그러나 4nm 및 6nm 두계의 Ti 박막을 확산방지층으로 증착한 Ti$O_{2}$/Ti/Ag/Ti/Ti$O_{2}$ 구조의 5층 박막에서는 transfer matrix를 사용하여 예측한 $TiO_{2}/Ag/TiO_{2}$ 3층 박막의 투과도 곡선과 유사한 광학 특성을 얻을 수 있었다.

• 한국분말재료학회지
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• 제12권4호
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• pp.249-254
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• 2005

Titanium dioxide was prepared by Polymer Complex Solution Method(PCSM) according to the mole ratio of Titanium (IV) isopropoxide(TTIP)/solvent and polymer(Poly Ethylene Glycol). Polymer electrolytes were usually made by dispersing preproduced ceramic nanoparticles in a polymer matrix. Using this method, pure and nano-sized $TiO_2$ powder was synthesized through a simple procedure and polymer entrapment route. At the optimum amount of the polymer, the titanium ions are dispersed in solution and a homogeneous polymeric network is formed. The maximum intensity of anatase phase of $TiO_2$ was achieved by calcining at $500^{\circ}C$ for 2h. The synthesized $TiO_2$ powders were nano-sized and the average size was about 50nm. Anatase/Rutile ratio of the synthesized $TiO_2$ was 70%/30%.