• Resources Recycling
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• v.12 no.5
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• pp.10-15
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• 2003

In this study, the separation of rare earths and aluminium from the dried powder of waste cerium polishing slurry was investigated. Since cerium oxide, 40％ of rare earths, is the most stable state in rare earth, the dissolution of cerium oxide in acid solution is not easy. Therefore the dissolution process of cerium oxide by sulfation was examined in order to increase the recovery of rare earth. The rare earths could be separated from aluminum by double salt precipitation using sodium sulfate.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.11-15
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• 2018

The parts of equipment for semiconductor are protected by anodic aluminum oxide film to prevent corrosion. This study investigated contamination particle and cracking behavior of anodic oxidation in sulfuric acid containing cerium salt. The insulating properties of the sample were evaluated by measuring the breakdown voltage. It was confirmed that the breakdown voltage was about 50% higher when the cerium salt was added, and that the breakdown voltage after the heat treatment was 55% and 35% higher at $300^{\circ}C$ and $400^{\circ}C$, respectively. After heating at $300^{\circ}C$ and $400^{\circ}C$, cracks were observed in non cerium and cerium 3mM, and more cracks occur at $400^{\circ}C$ than at $30^{\circ}C$. The amount of contamination particles generated in the plasma is about 45% less than that of non-cerium specimens.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.3-9
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• 2005

In this study, the separation and recovery of cerium hydroxide was investigated from the wasted cerium polishing powders. Waste cerium polishing powder contains $64.5\;wt\%$ of rare earth oxide and the content of cerium oxide is $36.5\;wt\%$. Since cerium oxide, $56.3\%$ of rare earths, is the most stable state in rare earth, the dissolution of cerium oxide in acid solution is not easy. Therefore the process of rare earth oxide by sulfation and water leaching was examined in order to increase the recovery of rare earth. Rare earth elements were recovered in the form of $\Re{\cdot}Na(SO_{4})_{2}$ by the addition of sodium sulfate to leached solution. The slurry of rare earth hydroxide was prepared by the addition of $\Re{\cdot}Na(SO_{4})_{2}$ to sodium hydroxide solution. After the oxidation of cerous hydroxide($CE(OH)_{3}$) to ceric hydroxide($CE(OH)_{3}$) by aeration, ceric hydroxide was separated from other rare earth hydroxides by controlling the acidity of solution.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.212-215
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• 2016

In this paper, cerium doped lutetium pyrosilicate (LPS) powders with cerium content (0.05 and 0.07 mol%) were prepared by sol-gel process. The formation of lutetium pyrosilicate (LPS) phase was confirmed by XRD analysis for the powders heated at $1,200^{\circ}C$; in these powders, a single phase of $Lu_2Si_2O_7$ (LPS) was observed. Cerium doped lutetium pyrosilicate (LPS) powder was agglomerated and constituted of small spherical particles with diameters of about 300 nm. The photoluminescence spectra of the $Lu_2Si_2O_7:Ce^{3+}$ powders showed the characteristic of excitation and there was an emission spectrum for $Ce^{3+}$ in the host of $Lu_2Si_2O_7$. The emission spectrum shows a broad band in the range of 350-525 nm; the broad wavelength on the right side of the spectra should be ascribed to the same 5d-4f transitions of $Ce^{3+}$, as in the case of cerium doped $Lu_2Si_2O_7$ single crystals.

• Journal of Powder Materials
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• v.13 no.3 s.56
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• pp.192-198
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• 2006

The nanostructured cerium oxide powders were synthesized by spray thermal decomposition process for the use as the raw materials of resistive oxygen sensor. The synthesis routes consisted of 1) spray drying of water based organic solution made from cerium nitrate hydrate ($Ce(NO_3){_3}6H_2O$) and 2) heat treatment of spray dried precursor powders at $400^{\circ}C$ in air atmosphere to remove the volatile components and identically to oxidize the cerium component. The produced powders have shown the loose structure agglomerated with extremely fine cerium oxide particles with about 15 nm and very high specific surface area ($110m^2/g$). The oxygen sensitivity, n ($Log{\propto}Log (P_{O2}/P^o)^{-n}$ and the response time, $t_{90}$ measured at $600^{\circ}C$ in the sample sintered at $1000^{\circ}C$, were about 0.25 and 3 seconds, respectively, which had much higher performances than those known in micron or $100{\sim}200nm$ sized sensors.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.248-259
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• 2014

Acceptor-doped cerium pyrophosphates have shown significant proton conductivity of > $10^{-2}Scm^{-1}$ in the range of $100-300^{\circ}C$ and are considered promising candidates for use as electrolytes in proton-conducting, ceramic electrolyte fuel cells (PCFCs). But, cerium pyrophosphates themselves do not have structural protons, and protons incorporate into their material bulk only as impurities on exposure to a hydrogen-containing atmosphere. However, proton incorporation and proton conduction in these materials are expected to be affected by factors such as the nature (ionic size and charge) and concentration of the aliovalent dopant, processing history (synthesis route and microstructure), and the presence of residual phosphorous phosphate ($P_mO_n$) phases. An exact understanding of these aspects has not yet been achieved, leading to large differences in the magnitude of proton conductivity of cerium pyrophosphates reported in various studies. Herein, we systematically address some of these aspects, and present an overview of factors affecting proton conductivity inacceptor-doped $CeP_2O_7$.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3059-3064
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• 2013

In this study transesterification of Triglycerides (TG) from Jatropha curcas oil (JCO) with methanol for production of biodiesel was investigated over cerium impregnated ZSM-5 catalysts. NaZSM-5 was synthesized in an alkaline medium and impregnated with cerium oxide by wet method using cerium nitrate as a source for cerium. They were characterized by X-ray diffraction (XRD), Thermogravimeteric analysis (TGA), $CO_2$-temperature programmed desorption, and $N_2$ adsorption/desorption analysis. XRD analysis showed decrease in intensity of the patterns with the increase in the ceria loading but crystallization of ceria to larger size is an evident for 10 and 15% loading. The optimal yield of transesterification process was found to be 90% under the following conditions: oil to methanol molar ratio: 1:12; temperature: $60^{\circ}C$; time: 1 h; catalyst: 5 wt %. Here the yield of fatty acid methyl ester (FAME) was calculated through $^1H$ NMR analysis. The investigation on catalyst loading, temperature, time and reusability illustrated that these ceria impregnated NaZSM-5's were found to be selective, recyclable and could yield biodiesel at low temperature with low methanol to oil ratio due to the presence of both Lewis and Bronsted basicity. Hence, from the above study it is concluded that ceria impregnated ZSM-5 could be recognized as a potential catalysts for biodiesel production in industrial processes.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.414-417
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• 2012

The effect of cerium concentration and the addition of $Sb_2O_3$ on the light emission of cerium-contained glass were investigated. The glass matrix composition was $20Y_2O_3-25Al_2O_3-55SiO_2$, the $CeO_2$ concentration ranged from 0.05 to 0.5 mol%, and $Sb_2O_3$ was added at concentrations of 0.02 to 0.1 mol%. The $Ce^{3+}$ and $Ce^{4+}$ absorption bands were observed at approximately 330 nm and 240 nm, respectively. A broad emission band at 400 nm, due to the 4f-5d transition of the $Ce^{3+}$ ion, was observed under illumination by a UV light at 330 nm. The photoluminescence intensity of $Ce^{3+}$ had a maximum value at a $CeO_2$ concentration of 0.1 mol%. Adding $Sb_2O_3$ decreased the $Ce^{4+}$ absorption intensity and enhanced the light emission intensity of $Ce^{3+}$ by about 45%.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.189-189
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• 2015

In this study, the corrosion resistance and adhesion of electrophoretic paint (E-paint) were studied on AZ31 magnesium alloy pretreated in cerium chemical conversion coating solutions with the addition of various ethanol concentrations. It was found that with increasing ethanol concentration from 0 to 90 percent can decrease the formation of $Mg(OH)_2/MgO$ and increase the formation of nano-crystalline cerium oxides on the coating. Both corrosion resistance and adhesion of E-painted AZ31 increased with increasing ethanol concentration. The best E-paint sample was observed on the sample pretreatment in cerium chemical conversion coating solution with the addition of 80 percent of ethanol. This sample showed an excellent adhesion without paint detached after water immersion test for 500 h at $40^{\circ}C$, and only a few blisters observed at the near scratched sites after 1000 h salt-spray test.

• Journal of Integrative Natural Science
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• v.13 no.1
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• pp.13-18
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• 2020

This study used cerium iron hydroxide nanoparticle with HEMA (2-hydroxyethyl methacrylate), the cross-linker EGDMA (ethylene glycol dimethacrylate), NVP (N-vinyl-2-pyrrolidone) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Also, the physical properties of the prepared lenses were compared, and their applicability as polymers for ophthalmic materials was experimented. The results of the measurement showed that the UV blocking rate and the wettability increased with the cerium iron hydroxide nanoparticles addition ratio, and the refractive index and water content were not affected. Thus, the produced copolymer is expected to be useful as a functional contact lens material while satisfying the basic physical properties of the hydrogel contact lens.