• Journal of the Korean Ceramic Society
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• v.42 no.5 s.276
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• pp.352-358
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• 2005

By calcining at $750^{\circ}C$ for 30 h in $O_2$ stream after milling, $LiNi_{1-y}M_yO_2(M=Zn^{2+},\;Al^{3+}$, and $Ti^{4+}$, y = 0.005, 0.01, 0.025, 0.05, and 0.1) were synthesized and their electrochemical properties were investigated. All the samples had R3m structure. $LiNi_{1-y}Zn_yO_2$ (y = 0.025, 0.05, and 0.1) contained ZnO anuor $Li_2ZnO_2$ as impurities. Among the samples substituted with the same element, the samples with relatively large value of $I_{003}/I_{104}$ and the smallest R-factor had the largest first discharge capacity and good cycling performance. $LiNi_{0.975}A1_{0.025}O_2$ had the largest first discharge capacity (172.5 mAh/g) and good cycling performance (about $89.4\%$ of the first discharge capacity at the 20th cycle). This sample had the largest value of $I_{003}/I_{104}$ and the smallest R-factor among all the samples. In addition, the particles of this sample were finer and their size was more homogeneous than the other samples. $LiNi_{0.95}A1_{0.05}O_2$ had relatively large first discharge capacity 150.4 mAh/g and good cycling performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.133-136
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• 1999

We report on the electrochemical properly of LiZ $n_{x}$Mn $_{2-x}$ $O_4$ for different degrees of Zn substitution(x) Though all cathode material showed spinel phase based on cubic phase in X-ray diffraction, other peaks(M $n_2$ $O_3$ or M $n_3$ $O_4$) gradually exhibited and became intense with the increase of x vague in LiZ $n_{x}$Mn $_{2-x}$ $O_4$. In addtion, TG-DTA analysis exhibited that both LiM $n_2$ $O_4$ and LiZ $n_{0.1}$ M $n_{1.9}$ $O_4$ occurred the weight loss(TG) and the endothermic and exothermic reaction(DTA) until 80$0^{\circ}C$ When x=0.1 in LiZ $n_{x}$Mn $_{2-x}$ $O_4$ cathode materials showed the charge and discharge capacity of about 100mAh/g at first cycle and about 70mAh/g after tooth cycle.cle.e.cle.e.e.e.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.121-121
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• 2010

ZnO is a promising material for the application of high efficiency light emitting diodes with short wavelength region for its large bandgap energy of 3.37 eV which is similar to GaN (3.39 eV) at room temperature. The large exciton binding energy of 60 meV in ZnO provide provides higher efficiency of emission for optoelectronic device applications. Several ZnO/ZnMgO multiple quantum well (MQW) structures have been grown on various substrates such as sapphire, GaN, Si, and so on. However, the achievement of high quality ZnO/ZnMgO MQW structures has been somehow limited by the use of lattice-mismatched substrates. Therefore, we propose the optical properties of ZnO/ZnMgO multiple quantum well (MQW) structures with different well widths grown on lattice-matched ZnO substrates by molecular beam epitaxy. Photoluminescence (PL) spectra show MQW emissions at 3.387 and 3.369 eV for the ZnO/ZnMgO MQW samples with well widths of 2 and 5 nm, respectively, due to the quantum confinement effect. Time-resolved PL results show an efficient photo-generated carrier transfer from the barrier to the MQWs, which leads to an increased intensity ratio of the well to barrier emissions for the ZnO/ZnMgO MQW sample with the wider width. From the power-dependent PL spectra, we observed no PL peak shift of MQW emission in both samples, indicating a negligible built-in electric field effect in the ZnO/$Zn_{0.9}Mg_{0.1}O$ MQWs grown on lattice-matched ZnO substrates.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.307-316
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• 2014

Improved power conversion efficiency of hybrid solar cells with ITO/ZnO seed layer/ZnO NRs/ZnS QDs/P3HT/PCBM/Ag structure was obtained by optimizing the growth period of ZnO nanorods (NRs). ZnO NRs were grown using a hydrothermal method on ZnO seed layers, while ZnS quantum dots (QDs) (average thickness about 24 nm) were fabricated on the ZnO NRs by the successive ionic layer adsorption and reaction (SILAR) technique. Morphology, crystalline structure and optical absorption of layers were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-Visible absorption spectra, respectively. The XRD results implied that ZnS QDs were in the cubic phase (sphalerite). Other experimental results showed that the maximum power conversion efficiency of 4.09% was obtained for a device based on ZnO NR10 under an illumination of one Sun (AM 1.5G, $100mW/cm^2$).

• Elastomers and Composites
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• v.52 no.2
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• pp.131-135
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• 2017

Zinc nitrate hexahydrate [$Zn(NO_3){\cdot}6H_2O$] and sodium hydroxide [NaOH] were used as source reagents in the preparation of ZnO nanoparticles in an aqueous solution containing deionized water and ethanol in a ratio of 2:5 (v/v). ZnO nanoparticles were heated in an electric furnace at $700^{\circ}C$ for 2 h under an atmosphere of inert argon gas. The morphological and structural properties of the nanoparticles were characterized by scanning electron microscopy (SEM) and powder X-ray diffractometry (XRD). UV-vis spectrophotometry was used to analyze the photocatalytic degradation of 3-nitrophenol with ZnO nanoparticles as photocatalyst under ultraviolet irradiation at 254 nm. Evaluation of the kinetic of the photo-catalytic degradation of 3-nitrophenol indicated that the degradation of 3-nitrophenol with ZnO nanoparticles obeyed the pseudo-first order reaction rate model.

• Journal of the Korean Ceramic Society
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• v.24 no.3
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• pp.227-234
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• 1987

With the content of ZnO varing from 10.5 to 47.4 wt%, the crystallization of lithium zinc silicate glass was investigated by DTA, XRD, and SEM. In this work P2O5 was used as nucleation agent. The crystallization temperature was found to increase with the content of ZnO and the microstructure of formed crystalling phases was studied through the scanning electron microscopy. According to the XRD analysis, the crystal phases formed are summarized as follows. 1) The major phases are lithium orthosilicate, lithium disilicate and quartz at 10.5 wt% ZnO. 2) Lithium zinc silicate polymorphous and cristobalite occur in the composition varying 21.3 to 30.8 wt% ZnO. 3) At composition containing 47.4wt% ZnO some quantity of willemite is formed.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.232-237
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• 2007

We have synthesized the low temperature sintered of Ni-Zn-Cu ferrite with nonstoichiometric composition a little deficient in $Fe_2O_3$ from $(Ni_{0.2}Cu_{0.2}Zn_{0.6})_{1+x}(Fe_2O_3)_{1-x}$. For low loss and acceleration of grain growth $TiO_2$ and $Li_2CO_3$ was added from 0.25 mol% to 1.0 mol%. The mixture of the law materials was calcinated and milled. The compacts of toroidal type were sintered at different temperature $(875^{\circ}C,\;900^{\circ}C,\;925^{\circ}C\;950^{\circ}C)$ for 2 hours in air followed by an air cooling. Then, effects of composition and sintering temperatures on the physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, and quality factor of the Ni-Zn-Cu ferrite were investigated. The density of the Ni-Zn-Cu ferrite was $4.85\sim5.32g/cm^3$, resistivity revealed $10^8\sim10^{12}\Omega-cm$. The magnetic properties obtained from the aforementioned Ni-Zn-Cu ferrite specimens were 1,300 gauss for the maximum induction, 4.5 oersted for the coercive force, 275 for the initial permeability, and 83 for the quality factor. The physical properties indicated that the specimens could be utilized as the core of high frequency range (involved microwave range) communication and deflection yoke of T.V.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1572-1573
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• 2006

This paper presents electrical properties of Zinc Oxide(ZnO) surge arrester blocks under the power frequency AC voltages and various temperatures. The leakage current, $I_{R}-V$ curios and power dissipation for the fine and aged ZnO surge arrester blocks were measured as a function of the temperatures and applied voltages. When the temperature is increased from $50\;[^{\circ}C]$ to $150\;[^{\circ}C]$, the total leakage current significantly increased at the sane applied voltage level. Also, the resistive leakage currents and power dissipation were increased with increasing temperature. The leakage current and power dissipation of the aged ZnO arrester blocks were higher than the fine ZnO arrester blocks.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.2
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• pp.152-155
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• 2007

In this study, we fabricated FBAR(film bulk acoustic resonator) by using $Li_{2}CO_{3}:ZnO$ as a function of annealing temperature and concentrated on effect of frequency characteristic of FBAR. The results show that the annealing affects resistivity and crystallity. The optimum properties were observed for film annealed at $500^{\circ}C$. The resistivity was $1.5{\times}10^{11}\;{\Omega}{\cdot}cm$ and the roughness was 21.10 nm. And the return loss is improved from -24.9 at $300^{\circ}C$ to -29.8 at $500^{\circ}C$ without the resonant frequency change. We finally confirmed the improvement on the frequency characteristics of FBAR device by annealing process at the optimized condition.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.175.1-175
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• 2003