• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.343-343
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• 2011

ZnO has been introduced as one of the good candidates for next generation opto-electronics. Recently, ZnO is known to be suitable for the transparent electrode in organic solar cells and light emitting devices. The contact with n-type organic material has been studied due to the n-type properties of ZnO. However, the surface of ZnO has shown different electronic property with respect to its surface orientation. Therefore, it is presumed that there are differences in the interfacial electronic structures between organic materials and ZnO with different orientation. Therefore, it is required to classify the interfacial electronic structures according to the surface orientation of ZnO. In this study, we measured the interfacial electronic structures between the ZnO substrate having various orientations and a typical n-type organic material, tris-(8-hydroxyquinoline) aluminum (Alq3). In-situ x-ray and ultraviolet photoelectron spectroscopy measurements revealed the interfacial electronic structures. We found the changes in the electronic structures with respect to the orientation of ZnO substrate and it could be used to improve the contact between ZnO and Alq3.

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.251-256
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• 2011

The luminescence properties of polycrystalline ZnO annealed in reducing ambience ($H_2/N_2$) have been studied. An effective quenching of green luminescence with enhanced UV emission from polycrystalline ZnO is observed for the reduced ZnO. The variations of the UV and green luminescence band upon reduction treatment are investigated as a function of temperature in the range between 20 and 300 K. Upon annealing treatment in reducing ambience, the optical quality of polycrystalline ZnO is improved. The UV to green intensity ratio of sintered ZnO approaches close to zero (~0.05). However, this ratio reaches more than 13 at room temperature for polycrystalline ZnO annealed at $800^{\circ}C$ in reducing ambience. Furthermore, the full width at half maximum (FWHM) of the UV band of polycrystalline ZnO is reduced compared to unannealed polycrystalline ZnO. Electron paramagnetic resonance (EPR) measurements clearly show that there is no direct correlation between the green luminescence and oxygen vacancy concentration for reduced polycrystalline ZnO.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.156-161
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• 2015

The electronic structures of the potential candidate semiconductor nanoparticles for dye-sensitized solar cell (DSSC), such as $ZnSnO_3$ and $Zn_2SnO_4$, have been investigated by employing X-ray photoemission spectroscopy (XPS). The measured X-ray diffraction patterns show that $ZnSnO_3$ and $Zn_2SnO_4$ samples have the single-phase ilmenite-type structure and the inverse spinel structure, respectively. The measured Zn 2p and Sn 3d core-level XPS spectra reveal that the valence states of Zn and Sn ions are divalent (Zn 2+) and tetravalent (Sn 4+), respectively, in both $ZnSnO_3$ and $Zn_2SnO_4$. On the other hand, the shallow core-level measurements show that the binding energies of Sn 4d and Zn 3d core levels in $ZnSnO_3$ are lower than those in $Zn_2SnO_4$. This work provides the information on the valence states of Zn and Sn ions and their chemical bonding in $ZnSnO_3$ and $Zn_2SnO_4$.

• Membrane Journal
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• v.26 no.6
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• pp.463-469
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• 2016

In this research, a new expectation in enhancing the PES (polyethersulfone) polymer phase inversion membrane performances with nanoparticles is proposed by using ZnO. This paper investigated the synthesis of PES phase inversion membranes including ZnO nanoparticles and evaluates the performance of these mixed matrix membranes. The PES-ZnO mixed matrix membranes were fabricated by phase inversion method using the PES-ZnO-NMP(N-methyl-1-pyrrolidone) casting solutions with low ZnO nanoparticles content of 0.375 wt%. The influence of ZnO nanoparticles on the characteristics of PES-ZnO mixed matrix membranes was investigated with scanning electron microscope observations of membrane cross-sections, contact angle measurements, tensile strength measurements, pure water flux measurements and ultrafiltration experiments of BSA solution. Those results showed that the performance advancements in comparison with the pure PES membrane without ZnO in terms of increasing hydrophilicity as well as reducing membrane fouling by adding ZnO nanoparticles even in low concentration.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1093-1096
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• 2001

The Solid solution of A $l_2$ $O_3$ into ZnO can be defined by the substitution reaction of Al$\^$3+/ ions into the Zn$\^$2+/ sites of ZnO crystal lattice, the tetrahedral interstices composed of four neighbor oxygen ions in the wurtzite structure. Since the reaction either creates new zinc vacancies or consumes the oxygen vacancies, it should be in equilibrium with ZnO nonstoichiometry and disorder reactions. The relationships make oxygen partial pressure P$\sub$o2/ control the concentrations of the vacancies and consequently limit the Al solubility in ZnO, [Al$\sub$zn/]$\sub$max/. This paper firstly reports with a refined model for defect quilibria in ZnO that the solubility decrease with the increase of P$\sub$o2/, [Al$\sub$zn/]$\sub$max/ P$\sub$o2/$\^$-1/4/.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.6
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• pp.992-1001
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• 2020

Objective: This study was conducted to investigate the effects of hot-melt extruded ZnO nano-particles (HME-ZnO) as an alternative for P-ZnO on growth performance, nutrient digestibility, Zn bioavailability, intestinal microbiota, and intestinal morphology of weanling pigs. Methods: A total of 450 piglets (Landrace×Yorkshire×Duroc) were randomly allotted to five treatments based on initial body weight and sex. The experimental diets were fed in a meal form as phase 1 from d 0 to 14 and phase 2 from d 15 to 28. Treatments were the control diet without ZnO supplementation, the diet containing 2,500 ppm Zn as ZnO, and three diets containing 500, 1,000, or 2,500 ppm Zn as HME-ZnO. Results: The overall result showed a higher (p<0.01) average daily gain in weanling pigs fed ZnO-supplemented diets in comparison to the control diet. There was a decrease (p<0.01) in fecal score in the ZnO-supplemented diets. Dietary supplementation of ZnO improved (p<0.05) crude protein digestibility. The weanling pigs fed the P-ZnO diet had a lower (p<0.01) Zn digestibility in the feces than HME-ZnO supplemented treatments. Weanling pigs fed diets supplemented with ZnO had greater (p<0.05) Lactobacillus spp. populations and lower Clostridium spp. (p<0.05) and Coliforms (p<0.01) populations in the ileum. Weanling pigs fed diets supplemented with increasing concentrations of HME-ZnO linearly decreased Clostridium spp. (p<0.05) and Coliforms (p<0.01) in the ileum. Lower (p<0.05) Clostridium spp. and Coliforms counts in the colon were observed in pigs fed with ZnO-supplemented diets. Weanling pigs fed diets supplemented with ZnO showed a greater (p<0.01) villus height in the duodenum. Conclusion: Dietary supplementation of HME-ZnO and P-ZnO showed a potential to improve the digestibility of protein, intestinal Coliform and Clostridium, villus height in duodenum and ileum. Moreover, HME-ZnO showed a higher Zn digestibility compared with P-ZnO.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.176-185
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• 1995

To improve photosensisitizing efficiency of ZnO/$H_2Pc(I)_x$ system, ZnO/$H_2Pc(I)_x$ system was dispersed in a typical photoconductive polymer of poly(9-vinylcarbazole)(PVCZ). The iodine dopant level(x) of ZnO/${\chi}-H_2Pc(I)_x$ is proportional to concentration of iodine, whereas x of ZnO/${\beta}-H_2Pc(I)_x$ decreased from the highest x=0.97 at more than $6.3{\times}10^{-3}$ M iodine solution. The Raman spectra of ZnO/${\chi}-H_2Pc(I)_x$ at 514 nm exhibited characteristic $I_3^-$ patterns in the range of 50∼550 $cm^{-1}$ at $x{\geq}0.57.$ The surface photovoltage of ZnO/${\chi}-H_2Pc(I)_{0.48}$/PVCZ was approximately 1.6 times greater than ZnO/${\chi}-H_2 Pc(I)_{0.48}$ and was 1.8 times of ZnO/${\chi}-H_2Pc(I)_{0.57}$/PVCZ at 670 nm. With ZnO/$H_2Pc(I)_x$/PVCZ, the highest iodine dopant levels showed a higher photovoltage. Therefore the injection of holes from H2Pc into PVCZ resulted in that photosensisitizing effect of ZnO/$H_2Pc(I)_x$/PVCZ system was improved compared to ZnO/$H_2Pc(I)_x$ case.

• Journal of the Korean Ceramic Society
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• v.19 no.4
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• pp.287-292
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• 1982

Nonohmic properties of ZnO ceramics with various small amounts of additives were studied in relation to experimental methods, additive contant and sintaring temperature. The kinds of additives used to following chemicals were basic additives ($0.5Bi_2O_3$, $0.3BaCO_3$, $0.5MnCO_3$, $0.5Cr_2O_3$, $0.1KNO_3$), $TiO_2$ and $Al(OH)_3$. Expecially, this study has focused on the effectsof $TiO_2$ and $Al(OH)_3$ in ZnO ceramics with the basic additives. SEM studies indicated that the addition of TiO2 promoted grain growth but retarded grain growth with the addition of $Al(OH)_3$. Also, in the case of calcination of ZnO with $TiO_2$ and ZnO with $Al(OH)_3$ previously, grain size of ZnO with $TiO_2$ was larger and that of ZnO with Al(OH)3 was smaller in comparison to the case with out calcination. From the viewpoint of nonohmic exponent and nonohimic resistance, electrical characteristics of ZnO, $TiO_2$ and the basic additives was more effective than that of ZnO, $Al(OH)_3$ and the basic additives. Nonohmic exponent and nonohmic resistance of ZnO, $TiO_2$ and the basic additives was 11-13 and 40-65 respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.1
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• pp.65-69
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• 2003

ZnO-Si-ZnO multi-layer thin films have been deposited by pulsed laser deposition (PLD). And then, the films have been annealed at 300$^{\circ}C$ in oxygen ambient pressure. Peak positions of ultraviolet (UV) and visible region were changed by addition of Si layer. Mobility of the films was improved slightly than ZnO thin film without Si layer. The structural property changed by inserting intermediate Si layer in ZnO thin film. The optical properties and structural properties of ZnO-Si-ZnO multi-layer thin films were characterized by PL(Photoluminescence) and XRB(X-ray diffraction) method, respectively. Electrical properties were measured by van der Pauw Hall measurements

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.106-112
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• 1995

In order to examine the effect of CuO and Al2O3 addition on the electrical conductivity of ZnO, both Al2O3 (0, 1, 2, 5, 10at.%) and CuO (1, 5at.%) were added to ZnO. Al2O3 addition (~2at.% Al) increased the total electrical conductivity of ZnO which was already decreased by CuO doping effect Above solid solubility of Al (~2at.%), ZnAl2O4 formed and the total electrical conductivity decreased due to the decrease of sintered density. Impedance measurements were used to know the reason and degree of contribution of three resistive elements, ZnO grain, ZnO/CuO, and ZnO/ZnO grain boundaries, to the total electrical conductivity changed.