• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.297-297
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• 2007

The $(B_{0.5},Sr_{0.5})TiO_3$ ceramics, which added with low sintering materials $Li_2CO_3$ and ZnBO, was investigated for LTCC(low temperature co-fired ceramic) applications. To compare sintering temperature of $(B_{0.5},Sr_{0.5})TiO_3$ respectively, we added 1, 2, 3, 4, and 5wt% of $Li_2CO_3$ and ZnBO to $(B_{0.5},Sr_{0.5})TiO_3$. For confirming the sintering temperature, the respective specimens were sintered from $750^{\circ}C$ to $1200^{\circ}C$ by $50^{\circ}C$. The case of $Li_2CO_3$ greatly lowered the sintering temperature of $(B_{0.5},Sr_{0.5})TiO_3$ ($1350^{\circ}C$) below $900^{\circ}C$. The addition of ZnBO improved the loss tangent of $(B_{0.5},Sr_{0.5})TiO_3$. The crystalline structure of $LiCO_3$ doped $(B_{0.5},Sr_{0.5})TiO_3$ and ZnBO doped $(B_{0.5},Sr_{0.5})TiO_3$ was analyzed with the X-ray diffraction (XRD) analysis. The dielectric permittivity and loss tangent of $Li_2CO_3$ doped BST and ZnBO doped BST were measured with the HP 4284A precision. From the electrical characterization, we respectively obtained the dielectric permittivity 1361, loss tangent $6.94{\times}10^{-3}$ at $Li_2CO_3$ doped $(B_{0.5},Sr_{0.5})TiO_3$ (3wt%) and the dielectric constant 1180, loss tangent $3.70{\times}10^{-3}$ at ZnBO doped $(B_{0.5},Sr_{0.5})TiO_3$(5wt%).

• Korean Journal of Materials Research
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• v.34 no.8
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• pp.377-386
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• 2024

The surface of titanium (Ti) dental implants was modified by applying a zinc (Zn)-doped titanium dioxide (TiO₂) coating. Initially, the Ti surfaces were etched with NaOH, followed by a hydrolysis co-condensation using tetrabutyl titanate (TBT, Ti(OC₄H₉)₄) and zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O), with ammonia water (NH₃·H₂O) acting as a hydroxide anion source. The morphology and chemical composition of the Zn-doped TiO₂-coated Ti plates were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and scanning electron microscopy (SEM). Synthesis temperatures were carefully adjusted to produce anatase Zn-doped TiO₂ nanoparticles with a bipyramidal structure and approximate sizes of 100 nm. Wettability tests and cell viability assays demonstrated the biomedical potential of these modified surfaces, which showed high biocompatibility with a survival rate of over 95 % (p < 0.05) and improved wettability. Corrosion resistance tests using potentiodynamic polarization reveal that Zn-TiO₂-treated samples with an anatase crystal structure exhibited a lower corrosion current density and more noble corrosion potential compared to samples coated with a rutile structure. This method offers a scalable approach that could be adapted by the biomaterial industry to improve the functionality and longevity of various biomedical implants.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.3021-3024
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• 2009

$Zn_2Ti_{1-x}Fe_xO_4\;(0\;{\leq}\;x\;{\leq}\;0.7)$ photocatalysts were synthesized by polymerized complex (PC) method and investigated for its physico-chemical as well as optical properties. $Zn_2Ti_{1-x}Fe_xO_4$ can absorb not only UV light but also visible light region due to doping of Fe in the Ti site of $Zn_2TiO_4$ lattice because of the band transition from Fe 3d to the Fe 3d + Ti3d hybrid orbital. The photocatalytic activity of Fe doped $Zn_2TiO_4$ samples for hydrogen production under UV light irradiation decreased with an increase in Fe concentration in $Zn_2TiO_4$. Consequently, there exists an optimized concentration of iron for improved photocatalytic activity under visible light (${\lambda}{\leq}$420 nm)

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1117-1123
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.114-114
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• 1993

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.258-266
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• 1989

The effects of grain size and dopant ZnO on the photoelectrochemical conversion in TiO2 ceramic electrodes have been investigated. The photocurrent increases with increasing grain size in the undoped TiO2 ceramic electrode. In ZnO-doped TiO2 electrodes, the photocurrent decreases with increasing ZnO up to 0.4 wt% due to decrease of donor concentration, and then with further addition of ZnO, photocurrent increases according to the formation of second phase. However, the photoresponse appears at wavelength of 420nm, which is very close to the energy band gap of TiO2, regardless of grain size and amount of ZnO.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.94-98
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• 2020

The core/shell of nanowires (NWs) with Cu-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We presented CdSe with Cu2+ dopants that were synthesized by a colloidal process. An improvement of the recombination barrier, due to shell supplementation with Cu-doped CdSe quantum dots. The enhanced cell steady state was attributable to TiO2 with Cu-doped CdSe QD supplementation. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 arrays was investigated to represent the merit of core/shell as an electron transport layer in effective devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.121-124
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• 1998

Generally the structure of powder electroluminescent devices (PELDs) on ITO-film was makeup of the ZnS:Cu phosphor layer and BaTiO$_3$ insulating layer. The active layer, which consists of a suitably doped ZnS powder mixed in a dielectric, is sandwiched between two electrodes; one of which are ITO film and the other is aluminum. In this paper, three kinds of powder eleotroluminescent devices (PELDs) : WK-A(ITO/BaTiO$_3$/ZnS:Cu/Silver paste). WK-B(ITO/BaTiO$_3$+ZnS:Cu/Silver paste) and WK-C(ITO/BaTiO$_3$/ZnS:Cu/BaTiO$_3$/Silver paste), fabricated by spin coating method, were investigated. To evaluate the luminescence properties of three kinds of PELDs, EL emission spectroscopy, transferred charge density and time response of EL emission intensity under square wave voltage driving were measured.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.392-392
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• 2011

현재의 태양전지에 사용되는 wafer는 원가저감을 위해 점점 얇아지고 있는 추세이다. 하지만 wafer가 얇아질수록 장파장 영역의 광자는 충분히 활용할 수 없게 된다. 대부분의 광자는 50um 지점에 도달하였을 때 그 역할을 다하고 소멸하게 되며, 특히 800nm 이상의 장파장에 대한 generation rate는 wafer 두께에 따라 급격한 차이를 보이게 된다. 따라서 장파장 영역의 광자를 효율적으로 사용할 뿐만 아니라 원가 저감을 위해 더욱 얇아지고 있는 추세의 wafer의 장파장 이용을 보상하기 위해서 TCO를 이용한 back-reflector의 역할은 가장 좋은 해결책이 될 것이다. 본 연구에서는 Macleod를 이용하여 ZnO, Al-doped ZnO, TiN, TiO2와 같은 다양한 TCO 물질에 대한 다양한 simulation을 실시 하여 reflectance 특성을 알아보았다. 상기 simulation결과로써 Al-doped ZnO가 가장 reflectance 특성이 좋게 나타났었으며 이를 이종접합 태양전지에 적용하여 광학적 및 전기적 특성 변화에 대해서 분석하였다.

• Environmental Engineering Research
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• v.23 no.2
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• pp.181-188
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• 2018

Photocatalytic oxidation in the presence of Fe-doped, Zn-doped or Fe-Zn co-doped $TiO_2$ was used to effectively decompose humic acids (HAs) in water. The highest HAs removal efficiency (65.7%) was achieved in the presence of $500^{\circ}C$ calcined 0.0010% Fe-Zn co-doped $TiO_2$ with the Fe:Zn ratio of 3:2. The initial solution pH value, inorganic cations and anions also affected the catalyst photocatalytic ability. The HAs removal for the initial pH of 2 was the highest, and for the pH of 6 was the lowest. The photocatalytic oxidation of HAs was enhanced with the increase of the $Ca^{2+}$ or $Mg^{2+}$ concentration, and reduced when concentrations of some anions increased. The inhibition order of the anions on $TiO_2$ photocatalytic activities was $CO{_3}^{2-}$ > $HCO_3{^-}$ > $Cl^-$, but a slightly promotion was achieved when $SO{_4}^{2-}$ was added. Total organic carbon (TOC) removal was used to evaluate the actual HAs mineralization degree caused by the $500^{\circ}C$ calcined 0.0010% Fe-Zn (3:2) co-doped $TiO_2$. For tap water added with HAs, the $UV_{254}$ and TOC removal rates were 57.2% and 49.9%, respectively. The $UV_{254}$ removal efficiency was higher than that of TOC because of the generation of intermediates that could significantly reduce the $UV_{254}$, but not the TOC.