• Journal of the Microelectronics and Packaging Society
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• v.9 no.2
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• pp.27-31
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• 2002

In this study, $CeO_2$ thin films were etched with an addition of $Cl_2$ gas to $Ar/CF_4$ gas mixing in an inductively coupled plasma (ICP) etcher by the etching parameter such as RF power of 700 W, chamber pressure of 15 mTorr and dc bias voltage of -200 volts. The etch rate of $CeO_2$ films was 250 $\AA$/min with an addition of 10% $Cl_2$ gas to $Ar/CF_4$ gas mixture and the selectivity to SBT film was 0.4 at that condition. The surface reactions of the etched $CeO_2$ thin films were investigated by X-ray photoelectron spectroscopy (XPS). It was analyzed that Ce peaks were mainly observed in Ce-O bonds formed $CeO_2$ or $Ce_2O_3$ compounds. Cl peaks were detected by the peaks of Cl $2p_{3/2}$ and Cl $2p_{1/2}$. Almost all of Cl atoms were combined with Ce atoms like $CeCl_x$ or $Ce_x/O_yCl_z$ compounds.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.255-258
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• 2002

In this study, $CeO_2$thin films were etched with an addition of $Cl_2$gas to $Ar/CF_4$gas mixing in an inductively coupled plasma(ICP) etcher. The surface reactions of the etched $_CeO2$thin films were investigated by X-ray photoelectron spectroscopy(XPS). It was analyzed that Ce peaks were mainly observed in Ce-O bonds formed $CeO_2$or $CeO_3$compounds. Cl peaks were detected by the peaks of Cl $2p_{3/2}$ and Cl $2p_{1/2}$. Almost all of Cl atoms were combined with Ce atoms like $CeCl_{x}$ compounds.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.388-392
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• 2002

In this work, the etching of $CeO_2$ thin films has been performed in an inductively coupled $Ar/CF_4/Cl_2$ plasma. The highest etch rate of the $CeO_2$ thin film ws 250 ${\AA}/min$ and the selectivity of CeO$_2$to SBT was 0.4 at a 10% additive $Cl_2$ into Ar/($Ar+CF_4$)gas mixing ratio of 0.8. From result of X-ray photoelectron spectroscopy (XPS) analysis, there are Ce-Cl and Ce-F bonding by chemical reaction between Cl, F and Ce. During the etching of $CeO_2$ thin films in $Ar/CF_4/Cl_2$ plama, Ce-Cl and Ce-F bond is formed, and these prodcuts can be removed by the physical bombardment of Ar ions. The 10% additive $Cl_2$ into the Ar/($Ar+CF_4$)gas mixing ratio of 0.8 could enhance the reaction between Cl, F and Ce.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.435-435
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• 2011

The electronic structure and various physical properties of CeO2, Ce2O3, PrO2, and Pr2O3 have been studied from the framework of Ab-initio by the all-electron projector-augmented-wave (PAW) method, as implemented VASP (Vienna Ab-initio Simulation Package). The generalized gradient approximation (GGA) with effective U (Ueff) has been used to explain the strong on-site Coulomb repulsion among the localized Ce 4f electrons. The dependence of selected observables of these materials on the Ueff parameter has been scrutinized. The studied properties contain lattice constants, density of states, and reaction energies of CeO2, Ce2O3, PrO2, and Pr2O3. For CeO2 and PrO2, the GGA(PBE)+U results are in good agreement with experimental data whereas for the computational calculationally more demanding Ce2O3 and Pr2O3 both approaches give comparable accuracy. This results represent that by choosing an appropriate Ueff it is possible to reliably describe structural and electronic properties of CeO2, Ce2O3, PrO2, and Pr2O3, which enables modeling of oxygen reduction reaction processes involving ceria-based materials.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.316-320
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• 1976

Based on the results of graft copolymerization to proteins, an attempt is made to derive the rate equations to explain the mechanism of Ce(IV) ion-initiated graft copolymerizations. In this system the oxidative termination by Ce(IV) $[R{\cdot}+ Ce(IV) ${\rightarrow}$ R(inert) + Ce(III) + H^+]$ is considered characteristic particularly in higher concentration of Ce(IV) ion. The change in the mode of termination reactions with change in Ce(IV) ion concentration makes possible the presence of an optimum Ce(IV) ion concentration for maximum graft copolymerization yield. This effect is reflected in presently derived equations.

• Clean Technology
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• v.26 no.4
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• pp.286-292
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• 2020

This study confirmed the effect of the Cu/CeO2-X catalyst on the CO oxidation activity at low temperature through the catalyst's structure and reaction characteristics. The catalyst was prepared by the wet impregnation method. Cu/CeO2_X catalysts were manufactured by loading Cu (active metal) using CeO2 (support) formed at different calcination temperatures (300-600 ℃). Manufactured Cu/CeO2_X catalysts were evaluated for the low-temperature activity of carbon monoxide. The Cu/CeO2_300 catalyst showed an activity of 90% at 125 ℃, but the activity gradually decreased as the calcination temperature of the CeO2-X and Cu/CeO2_600 catalysts showed an activity of 65% at 125 ℃. Raman, XRD, H2-TPR, and XPS analysis confirmed the physicochemical properties of the catalysts. Based on the XPS analysis, the lower the calcination temperature of the CeO2 was, the higher the unstable Ce3+ species (non-stoichiometric species) ratio became. The increased Ce3+ species formed a solid solution bond between Cu and CeO2-X, and it was confirmed by the change of the CeO2 peak in Raman analysis and the reduction peak of the solid solution structure in H2-TPR analysis. According to the result, the formation of the solid solution bond between Cu and Ce has been enhanced by the redox properties of the catalysts and by CO oxidation activity at low temperatures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.217-220
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• 2001

The possibility of cerium dioxide $(CeO_2)$ thin films as insulators of metal erroelectric insulator semiconductor (MFIS) structures have been studied. The etching $CeO_2$ thin films have been perfonned in an inductively coupled $Cl_{2}/CF_{4}/Ar$ plasma. The high etch rate of the $CeO_2$ thin film was $250\AA /m$ at a 10 % addition of $Cl_2$ into the $Ar(80)/CF_{4}(20)$. The surface reaction of the etched $CeO_2$ thin films was investigated using X-ray photoelectron spectroscopy (XPS) analysis. There are Ce-Cl and Ce-F bonding by chemical reaction between Cl, F and Ce. These products can be removed by the physical bombardment of incident Ar ions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.217-220
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• 2001

The possibility of cerium dioxide (CeO$_{7}$ ) thin films as insulators of metal erroelectric insulator semiconductor (MFIS) structures have been studied. The etching CeO$_2$ thin films have been performed in an inductively coupled C1$_2$/CF$_4$/Ar plasma. The high etch rate of the CeO$_2$ thin film was 250 ${\AA}$/m at a 10% addition of Cl$_2$ into the Ar(80)/CF$_4$(20). The surface reaction of the etched CeO$_2$ thin films was investigated using X-ray photoelectron spectroscopy (XPS) analysis. There are Ce-Cl and Ce-F bonding by chemical reaction between Cl, F and Ce. These products can be removed by the physical bombardment of incident Ar ions.

• ETRI Journal
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• v.22 no.3
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• pp.10-18
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• 2000

Although an n-th order cross-entropy (nCE) error function resolves the incorrect saturation problem of conventional error backpropagation (EBP) algorithm, performance of multilayer perceptrons (MLPs) trained using the nCE function depends heavily on the order of nCE. In this paper, we propose an adaptive learning rate to markedly reduce the sensitivity of MLP performance to the order of nCE. Additionally, we propose to limit error signal values at out-put nodes for stable learning with the adaptive learning rate. Through simulations of handwritten digit recognition and isolated-word recognition tasks, it was verified that the proposed method successfully reduced the performance dependency of MLPs on the nCE order while maintaining advantages of the nCE function.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.1
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• pp.56-64
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• 2011

This study was conducted to evaluate the use of exogenous enzymes as a potential means of improving the ruminal digestion (i.e., degradability) of alfalfa hay and rice straw. Twenty six enzyme-additives were examined in terms of protein concentration and enzymic activities on model substrates. The exogenous enzymes contained ranges of endoglucanase, xylanase, ${\beta}$-glucanase, ${\alpha}$-amylase, and protease activities. Six of the enzyme additives were chosen for further investigation. The enzyme additives and a control without enzyme were applied to mature quality alfalfa hay substrate and subsequently incubated in rumen batch cultures. Five of the enzyme additives (CE2, CE13, CE14, CE19, and CE24) increased total gas production (GP) at 48 h of incubation compared to the control (p<0.05). The two additives (CE14 and CE24) having the greatest positive effects on alfalfa hay dry matter, neutral detergent fibre (NDF) and acid detergent fibre (ADF) degradability were further characterized for their ability to enhance degradation of low quality forages. The treatments CE14, CE24, a 50:50 combination of CE14 and CE24 (CE14+24), and control (no enzyme) were applied to mature alfalfa hay and rice straw. For alfalfa hay, application of the two enzyme additives, alone and in combination, increased GP compared to the control at 48 h fermentation (p<0.05), whereas only CE14 and CE14+24 treatments improved GP from rice straw (p<0.05). Rumen fluid volatile fatty acid concentrations throughout the incubation of rice straw were analyzed. Acetate concentration was slightly lower (p<0.05) for CE14${\times}$CE24 compared to the control, although individually, CE14 and CE24 acetate concentrations were not different from the control. Increases (p<0.05) in alfalfa hay NDF degradability measured at 12 and 48 h of incubation occurred only for CE14 (at 12 h) and for CE14+24 (at 12 and 48 h). Similarly, ADF degradability increased (p<0.05) with CE14 and CE14+24. As for rice straw, increased DM degradability was observed at 12 and 48 h of incubation for all enzyme treatments with an exception for CE14 at 12 h. The degradability of NDF was improved by all the enzyme treatments at either incubation time, while ADF degradability was only enhanced at 48 h. Overall, the enzymes led to enhanced digestion of mature alfalfa and there was evidence of improved digestibility of rice straw, an even lower quality forage.