• Journal of Surface Science and Engineering
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• v.41 no.1
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• pp.12-15
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• 2008

The zinc oxide(ZnO) nanowires were deposited on Si(001) substrates by thermal chemical vapour deposition without any catalysts. SEM data suggested that the grown nanostructures were the well-aligned ZnO single crystals with preferential orientation. Back-gate ZnO nanowire field effect transistors(FET) were successfully fabricated using a photolithography process. The fabricated nanowire FET exhibits good contact between the ZnO nonowire and Au metal electrodes. Based on I-V characteristics it was found out that the ZnO nanowire revealed a characteristic of n-type field effect transistor. The drain current increases with increasing drain voltage, and the slopes of the $I_{ds}-V_{ds}$ curves are dependent on the gate voltage.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.122-122
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• 2010

ZnO is a widely investigated material for the blue and ultraviolet solid-state emitters and detectors. It has been promoted due to a wide-band gap semiconductor which has large exciton binding energy of 60 meV, chemical stability and low radiation damage. However, there are many problems to be solved for the growth of p-type ZnO for practical device applications. Many researchers have made an efforts to achieve p-type conductivity using group-V element of N, P, As, and Sb. In this letter, we have studied the optical characteristics of the antimony-doped ZnO (ZnO:Sb) thin films by means of photoluminescence (PL), PL excitation, temperature-dependent PL, and time-resolved PL techniques. We observed donor-to-acceptor-pair transition at about 3.24 eV with its phonon replicas with a periodic spacing of about 72 meV in the PL spectra of antimony-doped ZnO (ZnO:Sb) thin films at 12 K. We also investigate thermal activation energy and carrier recombination lifetime for the samples. Our result reflects that the antimony doping can generate shallow acceptor states, leading to a good p-type conductivity in ZnO.

• Transactions of Materials Processing
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• v.21 no.5
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• pp.324-329
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• 2012

Mg-(9-x)Sn-xAl-1Zn (x=1, 2, 3 and 4 wt.%) alloys were subjected to indirect extrusion, and the microstructure and mechanical properties of the as-extruded Mg-Sn-Al-Zn (TAZ) alloys were investigated. The TAZ 811 alloy exhibited a finer grain structure than the TAZ 541 alloy due to a larger number of Mg2Sn particles, which pinned the grain boundaries and prevented growth of recrystallized grains. The TAZ alloys showed an unusual yield asymmetry behavior. The tension-compression yield asymmetry increased with decreasing average grain size. The TAZ 811 alloy with a small grain size exhibited a larger yield asymmetry than that of the TAZ 541 alloy having a relatively large grain size, which is mainly attributed to the low Al content and large number of second phase particles in the TAZ 811 alloy.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.7
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• pp.1084-1091
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• 2007

Different levels of dietary mannanoligosaccharide (Bio-MOS, Alltech Inc.) were evaluated for their efficacy on performance and gut development of broiler chickens during a 6-week experimental period. Experimental diets contained (g MOS/kg diet) a low (0.5 g during the entire period), medium (1 g during the entire period), high (2 g during the entire period), or step down (2 g in the first week; 1 g in the second and third week; 0.5 g in the last three weeks) level of MOS. Control diets included a negative and a positive control (zinc bacitracin, ZnB, 50 ppm and 30 ppm in the first and last three weeks, respectively). MOS supplementation improved the growth performance of young birds and the effects became less when the birds got older. The growth response of birds was more obvious at the high dosage level of MOS treatment than the other MOS treatments and the growth performance of birds fed on the high MOS diet was comparable to that of birds fed on the ZnB diet. Depending on the dosage level and the age of birds, MOS seemed to reduce the size of the liver and the relative length of the small intestine but did not affect the relative weight of the other visceral organs (proventriculus, gizzard, pancreas, bursa and spleen) and that of the small intestine. A numerical increase in the small intestine digestibility of nutrients was noticed in the young birds fed on the MOS diet(s), but not in the older ones. Medium and/or high MOS treatment also increased the villus height of the small intestine of birds at different ages. Similar results were observed on the ZnB treatment. However, MOS and ZnB affected caecal VFA profile in different ways. MOS increased, or tended to increase, whereas ZnB reduced individual VFA concentrations in the caeca.

• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.179-184
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• 2017

In this paper, a $ZnO/SiO_2$ nano-composite was prepared by a simple chemical method at room temperature. For the synthesis of ZnO nanoparticles (NPs), a sonochemical method was used, and $SiO_2$ NPs were prepared by precipitation method. The formation of $ZnO/SiO_2$ NCs was characterized by X-ray diffractometer (XRD) and confirmed by field-emission scanning electron microscopy (FE-SEM) and Fourier transform infra-red spectroscopy(FT-IR). The photocatalytic properties of $ZnO/SiO_2$ NCs formed at different concentrations of $SiO_2$ were evaluated by rhodamine-B dye. It was confirmed that increasing $SiO_2$ concentration resulted in an increase in the photocatalytic property. In addition, the antibacterial activity of $ZnO/SiO_2$ NCs was conducted against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). As a result, the antibacterial activities of E.coli and S. aureus were increased in the presence of thick SiO NPs layer.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1869-1871
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• 2004

The primary role of ZnO arresters is to protect transmission and distribution equipments against lightning surges. The extremely nonlinear V-I characteristics of the ZnO arrester obviates the need for isolation gaps and consequently it is continuously connected to line voltage. For this reason, ZnO arresters are degraded with increasing with time in actual power systems. In this work, the characteristics of the luminous events between the ZnO block and electrodes were investigated. As a result, the luminous events were effected by the impulse and the near polarity of the luminous event was intense near the grounded electrode. Also the luminous event may cause the degradation of ZnO arrester block.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.26-28
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• 2004

The primary role of ZnO arresters is to protect transmission and distribution equipments against lightning surges. The extremely nonlinear V-I characteristics of the ZnO arrester obviates the need for isolation gaps and consequently it is continuously connected to line voltage. For this reason, ZnO arresters are degraded with time in actual power systems. In this work, the characteristics of the luminous events caused between the ZnO block and electrodes according to the electrode area were investigated. As a result, the luminous events were effected by electrode area and the longer electrode areas were increased, the more luminous events were decreased. Also the reduction of luminous events was fumed up to the degraded ZnO arrester block.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.21-27
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• 1998

Electrical and optical characteristics of ZnS:Mn/ZnS:Tb multilayer TFEL devices were investigated for multi-color electroluminescent display applications. Emission spectra of M $n^{2+}$ and T $b^{3+}$ ions were observed from ZnS:Mn/ZnS:Tb multi-layer TFEL devices, and were very broad from 540 nm to 640 nm. Saturation luminance measured at 155 V was 1025 Cd/$m^2$. C-V, $Q_{t}$ - $V_{p}$ curves showed that the phosphor capacitance ( $C_{p}$ ) and the insulator capacitance ( $C_{i}$ ) were 13.5nF/$\textrm{cm}^2$ and 60 nF/$\textrm{cm}^2$, respectively. Threshold voltage( $V_{thl}$) was shown to decrease from 126 V to 93 V due to the increase of the applied voltage from 155 V to 185 V, which was attributed to the increase of the polarization charge. The equation for the calculation of the threshold voltage as a function of the applied voltage was proposed for the first time. The calculated threshold voltage agreed well with the data obtained from the measurement.t.t.t.

• Transactions of Materials Processing
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• v.29 no.3
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• pp.135-143
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• 2020

Low-cost alloying elements were added to a modified Al-6.5Si alloy and its microstructure, tensile and impact toughness properties were investigated. The alloying elements added were Mg, Zn, and Cu, and two kinds of alloy A (Mg:0.5, Zn:1, Cu:1.5 wt.%) and alloy B (Mg:2, Zn:1.5, Cu:2 wt.%) were prepared. In the as-cast Al-6.5Si alloys, Si phases were distributed at the dendrite interfaces, and Al₂Cu, Mg₂Si, Al₆ (Fe,Mn) and Al₅ (Fe,Mn)Si precipitates were also observed. The size and fraction of casting defects were measured to be higher for alloy A than for alloy B. The secondary dendrite arm spacing of alloy B was finer than that of alloy A. It was confirmed by the JMatPro S/W that the cooling rate of alloy B could be more rapid than alloy A. The alloy B had higher hardness and strength compared to the values of alloy A. However, the alloy A showed better impact toughness than alloy B. Based on the above results, the deformation mechanism of Al-6.5Si alloy and the improving method for mechanical properties were also discussed.

• Advances in materials Research
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• v.11 no.3
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• pp.225-235
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• 2022

It includes the synthesis of pristine ZnO nanoparticles and a series of Ag-doped zinc oxide nanoparticles was carried out by reflux method by varying the amount of silver (1, 3, 5, 7 and 9% by mol.). The morphology of these nanoparticles was investigated by SEM, XRD and FT-IR techniques. These techniques show that synthesized particles are homogenous spherical nanoparticles having an average particle size of about 50-100 nm along with some agglomeration. The photocatalytic activity of the ZnO nanoparticles and Ag doped ZnO nanoparticles were investigated via photodegradation of methylene blue (MB) as a standard dye. The data from the photocatalytic activity of these nanoparticles show that 7% Ag-doped ZnO nanoparticles exhibit much enhanced photocatalytic activity as compared to pristine ZnO nanoparticles and other percentages of Ag-doped ZnO nanoparticles. Furthermore, 7% Ag-doped ZnO was made composites with sulfur-doped graphitic carbon nitride by physical mixing method and a series of nanocomposites were made (3.5, 7.5, 25, 50, 75% by weight). It was observed that the 25% composites exhibited better photocatalytic performance than pristine S-g-C 3 N 4 and pure 7% Ag-doped ZnO. Tauc's plot also supports the photodegradation results.