• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.724-727
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• 2009

We have fabricated (Ba,Sr)TiO3$TiO_3$ thick films doped with various amount of ZnBO dopants (1, 3, and 5 wt%) by screen printing method on the alumina substrates, which were sintered at the temperature below $1200^{\circ}C$. With increasing the amount of ZnBO dopants, the relative dielectric permittivity of ZnBO doped (Ba,Sr)$TiO_3$ was decreased, while loss tangent was increased. 1 wt% ZnBO doped (Ba,Sr)$TiO_3$ thick film has relative dielectric permittivity of 759 at 1 MHz, while 3 and 5 wt% of ZnBO doped (Ba,Sr)$TiO_3$ thick films have 624 and 554, respectively. By introducing ZnBO dopants to the (Ba,Sr)$TiO_3$ thick films, leakage current densities were decreased. The decreased leakage current with increasing ZnBO dopants can be explained by increased density and grain size of thick film on alumina substrate. We believe this decreased leakage current density probably come from the increased grain size and increased density.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3767-3771
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• 2012

In this study, we investigate the potential use of $TiO_2@SiO_2$ and $ZnO@SiO_2$ core/shell nanoparticles (NPs) as effective UV shielding agent. In the typical synthesis, $SiO_2$ was coated over different types of $TiO_2$ (anatase and rutile) and ZnO by sol-gel method. The synthesized $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs were characterized by UV-Vis, XRD, SEM and TEM. The UV-vis absorbance and transmittance spectra of core@shell NPs showed an efficient blocking effect in the UV region and more than 90% transmittance in the visible region. XRD and SAED studies confirmed the formation of amorphous $SiO_2$ coated over the $TiO_2$ and ZnO NPs. The FESEM and TEM images shows that coating of $SiO_2$ over the surface of anatase, rutile $TiO_2$ and ZnO NPs resulted in the increase in particle size by ~30 nm. In order to study the UV light shielding capability of the samples, photocatalytic degradation of methylene blue dye on $TiO_2@SiO_2$ and $ZnO@SiO_2$ NPs was performed. Photocatalytic activity for both types of $TiO_2$ NPs was partially suppressed. In comparison, the photocatalytic activity of ZnO almost vanished after the $SiO_2$ coating.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.301-302
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• 2012

본 연구에서는 ripple 형태의 ZnO 박막을 역구조 태양전지의 전자 수집층으로 사용하였으며, 원자층 증착법 (Atomic Layer Deposition, ALD)을 이용하여 $TiO_2$ 박막을 ZnO 표면에 증착하였다. $TiO_2$가 ZnO 표면 위에 약 <3nm 정도 두께의 초미세 박막으로 형성되었을 경우 태양전지의 성능이 향상되었다. 특히 Jsc (short-circuit current)와 전환효율 값의 향상을 보였다. 반면 $TiO_2$를 더 두껍게 증착되었을 경우 오히려 태양전지 성능이 떨어지는 결과를 얻었다. 이와 같은 결과 전자를 수집하는 ZnO 위에서 $TiO_2$가 장벽으로 작용함으로써 전자의 이동을 억제하기 때문으로 풀이된다. 반면 $TiO_2$가 초미세 박막으로 형성되었을 때 ZnO 표면에 존재하는 결함자리, 즉 전자와 정공이 재결합하는 자리를 덮어줌으로써 오히려 태양전지의 성능을 향상시키게 된다. 본 연구에서는 ALD 방법을 이용하여 $TiO_2$의 미세한 두께조절을 통해 태양전지 성능향상이 가능함을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.452-452
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• 2013

ZnO is one of the most attractive transparent conductive oxide (TCO) films because of low toxicity, a wide band gap material and relatively low cost. However, the electrical conductivity of un-doped ZnO is too high to use it as TCO films in practical application. To improve electrical properties of undoped ZnO, transition metal (TM) doped ZnO films such as Al doped ZnO or Ti doped ZnO have been extensively studied. Here, we prepared Ti doped ZnO thin films by atomic layer deposition (ALD) for the application of TCO films. ALD was used to prepare Ti-doped ZnO thin films due to its inherent merits such as large area uniformity, precise composition control in multicomponent thin films, and digital thickness controllability. Also, we demonstrated that ALD method can be utilized for fabricating highly ordered freestanding nanostructures of Ti-doped ZnO thin films by combining with BCP templates, which can potentially used in the photovoltaic applications.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.468-473
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• 2014

This study is unrefined ZnO, $TiO_2$ nanoparticles is expose M4 medium to search nanoparticle aggregation and Daphnia magna was any effect by immobilization and mortality. ZnO and $TiO_2$ nanoparticle powder-size is respectively 20 nm and 40 nm. but, M4 medium has about respectively as 1333 nm and 1628 nm, 40 to 70 times were agglomerated. Immobilization of ZnO and $TiO_2$ nanoparticles was influenced both time and concentration the higher to swimming of D.magna. Especially, The immobilization of D.magna in nano-ZnO is greater than that influence in nano-$TiO_2$. Mortality of ZnO nanoparticle is higher rate at long time and high concentration. $TiO_2$ nanoparticle observed mortality at 10ppm concentration after 72h. Consequently, when Nanoparticles is introduced into ocean. Particle size become grow. Additionally, aggregation be caused affect aquatic ecosystems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.300-302
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• 1996

Using the AC and DC methods we have studied th electrical properties of ZnO added TiO$_2$. The electrical conductivity of ZnO added TiO$_2$ was nearly unchanged with increasing the content of ZnO. Ac conductivity and conductance as a function of Frequency showed the similar trends. The impedance, admittance, and modulus spectrums were consistent with the results of DC conductivity.

• Korean Journal of Materials Research
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• v.19 no.3
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• pp.142-150
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• 2009

In this paper, non-treated ACF (Activated Carbon Fiber) /$TiO_2$ and Zn-treated ACF/$TiO_2$ were prepared. The prepared composites were characterized in terms of their structural crystallinity, elemental identification and photocatalytic activity. XRD patterns of the composites showed that the non-treated ACF/$TiO_2$ composite contained only typical single and clear anatase forms while the Zn-treated ACF/$TiO_2$ contained a mixed anatase and rutile phase with a unique ZnO peak. SEM results show that the titanium complex particles are uniformly distributed on and around the fiber and that the titanium complex particles are more regularly distributed on and around the ACF surfaces upon an increase of the $ZnCl_2$ concentration. These EDX spectra show the presence of peaks from the C, O and Ti elements. Moreover, peaks of the Zn element were observed in the Zn-treated ACF/$TiO_2$ composites. The prominent photocatalytic activity of the Zn-treated ACF/$TiO_2$ can be attributed to the three different effects of photo-degradation: doping, absorptivity by an electron transfer, and adsorptivity of porous ACFs between the Zn-$TiO_2$ and Zn-ACF.

• Electrical & Electronic Materials
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• v.3 no.1
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• pp.1-8
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• 1990

본 논문에서는 TiO$_{2}$첨가함량이 ZnO바리스터의 미세구조에 미치는 영양에 대해 검토하였다. 실험결과, TiO$_{2}$ 첨가함량이 증가함에 따라 ZnO 결정립의 평균크기는 점차적으로 감소하였으며 스피넬상은 증가하였다. 그리고 TiO$_{2}$ 첨가에 의해 ZnO 결정립은 불균일하게 이상형으로 거대 성장되었으며 첨가함량 증가에 따라 거래 성장된 결정립의 크기도 증가하였다. 또한 TiO$_{2}$ 첨가함량 증가에 따라 파괴전압이 저하하였으며 이는 ZnO 입자의 평균크기가 증가하기 때문인 것을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.459.1-459.1
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• 2014

Because both $TiO_2$ and ZnO has superior characteristic optically and electrically, there are various of research for these materials. However, they have large band gap energy which correspond with not visible light, but UV light. To make up for this disadvantage, Quantum dots (CdS, CdSe) which can absorb the visible light could be deposited on $ZnO/TiO_2$ nanostructure so that the the photoelectrochecmical cell can absorb the light that has larger region of wavelength. Both $TiO_2$ and ZnO can be grown to one-dimensional nanowire structure at low temperature through solutional method. Three-dimensional hierarcical $ZnO/TiO_2$ nanostructure is fabricated by applying these process. Large surface area of this structure make the light absorbed more efficiently. Through type 2 like-cascade energy band structure of nanostructure, the efficient separation of electron-hole pairs is expected. Photoelectrochemical charateristics are found by using these nanostructure to photoelectrode.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.503-507
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• 1998

Sintering behavior and dielectric peroperties of $xCaTiO_3-La(Zn_{1/2}Ti_{1/2})O_3$ system were investigated for better understanding of the microwave dielectric materials. In $xCaTiO_3-(1-x)La(Zn_{1/2}Ti_{1/2})O_3$ systems, solid solution type was focused as a function of composition(x=0.4-0.6) and sintered density. With increasing the sintered density, the relative dielectric constant was decreased and Q value was increased and then saturated. In solid solution type, dielectric constant was increased with increasing $CaTiO_3$ content. In $0.5\;CaTiO_3-0.5\; La(Zn_{1/2}Ti_{1/2})O_3$ case, dielectric constant(=48) and temperature coefficient of resonace frequency$(=-1 ppm/^{\circ}C$) were obtained.