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51.
Minh-Vien Le Dah-Shyang Tsai Chia-Ying Yang Wen-Hung Chung Hsin-Yi Lee 《Electrochimica acta》2011,(19):6654
The crystal structure and proton conductivity of cerium pyrophosphate are investigated to explore its potential electrolyte applications for intermediate temperature fuel cell. Among the CeP2O7 thin plates, which are sintered at 300–900 °C, the 450 °C CeP2O7 sample exhibits superior proton conductivity under humidified conditions. Its conductivity, measured with impedance spectroscopy, is higher than 10−2 S cm−1 in the intermediate temperature range, with a maximum value 3.0 × 10−2 S cm−1 at 180 °C. When 10 mol% Mg is doped on the Ce site of CeP2O7, the maximum conductivity is raised to 4.0 × 10−2 S cm−1 at 200 °C. The Mg doping not only raises the conductivity, but also shifts and widens its temperature window for electrolyte applications. Ce0.9Mg0.1P2O7 is considered a more appropriate composition, with conductivity >10−2 S cm−1 between 160 and 280 °C. Accordingly, a hydrogen–air cell is built with the Ce0.9Mg0.1P2O7 electrolyte and its performance is measured. The fuel cell generates electricity up to 122 mA cm−2 at 0.33 V using 50% H2 at 240 °C. 相似文献
52.
随铈的加入,合金中硫由正偏析变为负偏析,而本身强烈偏析于终凝区。结果表明:随着硫含量的增加,导致固液两相区、温度范围和偏析程度明显加大。 相似文献
53.
A process for surface modification of A16061-T6 has been carried out in molten salts containing Ce such as a NaCl---SnCl2---CeCl3 melt at 200 °C. Samples treated in molten salts for 2 h were subsequently exposed to a NaCl solution for 30 days to evaluate resistance against pitting corrosion. The coating mechanism in molten salts and the pitting corrosion behavior of the coated material have been studied by electrochemical impedance spectroscopy. The results show that this coating technique enhances the pitting corrosion resistance of aluminum alloys in contact with sea water. 相似文献
54.
Thermochemical hydrogen production from a two-step solar-driven water-splitting cycle based on cerium oxides 总被引:1,自引:0,他引:1
A new thermochemical cycle for H2 production based on CeO2/Ce2O3 oxides has been successfully demonstrated. It consists of two chemical steps: (1) reduction, 2CeO2 → Ce2O3 + 0.5O2; (2) hydrolysis, Ce2O3 + H2O → 2CeO2 + H2. The thermal reduction of Ce(IV) to Ce(III) (endothermic step) is performed in a solar reactor featuring a controlled inert atmosphere. The feasibility of this first step has been demonstrated and the operating conditions have been defined (T = 2000 °C, P = 100–200 mbar). The hydrogen generation step (water-splitting with Ce(III) oxide) is studied in a fixed bed reactor and the reaction is complete with a fast kinetic in the studied temperature range 400–600 °C. The recovered Ce(IV) oxide is then recycled in first step. In this process, water is the only material input and heat is the only energy input. The only outputs are hydrogen and oxygen, and these two gases are obtained in different steps avoiding a high temperature energy consuming gas-phase separation. Furthermore, pure hydrogen is produced (it is not contaminated by carbon products like CO, CO2), thus it can be used directly in fuel cells. The results have shown that the cerium oxide two-step thermochemical cycle is a promising process for hydrogen production. 相似文献
55.
56.
YVO4 single crystals doped with Ce3+, Er3+ and Yb3+ ions were grown by the Czochralsski technology. The luminescence properties of Er3+/Yb3+:YVO4 single crystals with different concentration of Ce3+ were studied, and the energy transfer mechanism between Er3+, Yb3+ and Ce3+ was discussed based on their energy level properties. The branching ratios of the 4I11/2 → 4I13/2 transition in different samples were calculated. The results indicate that codopants of Ce3+ greatly enhance the population rate of the 4I13/2 level due to the fast resonant energy transfer between Er3+ and Ce3+, i.e., 4I11/2(Er3+) + 2F7/2(Ce3+) → 4I13/2(Er3+) + 2F5/2(Ce3+). 相似文献
57.
A solid state reaction method was used to synthesize barium titanate (BT) and barium cerium titanate (BCT) ceramics at sintering temperature of 1473 K for 4 h. The effect of cerium (Ce) on the structure, microstructure and dielectric properties of BCT was investigated. The scanning electron microscopy (SEM) investigations revealed that the grain size increases with increasing Ce content. The X-ray diffraction (XRD) patterns showed mostly the BT phase, where the lattice parameter decreased with the addition of Ce. The temperature dependence of dielectric constant showed decrease in the phase transition temperature with higher Ce content. The dielectric constant decreased slightly with increasing frequency. The direct current (dc) density-voltage characteristics of the ceramics showed ohmic behavior for both the BT and BCT. As the temperature increased, the dc resistivity of the ceramics decreased. The activation energy increased with increasing Ce content. 相似文献
58.
Microstructures and crack extending characteristic of the YG8R,YT5R and YT14R hard alloysadding a trace cerium were studied by AEM and HVEM with a tensile holder.In the hard alloys addingcerium,the compounds of Ce_2O_3 or Ce_2O_2S could be formed,extending of stacking faults and transforma-tion from fcc Co to hcp Co were suppressed,volume fraction of fcc Co in the alloys was increased,andstrength of Co and(TiW)C phases and grain boundaries were raised.Plastic deformation in Co phase nearedges of the tensile cracks was more strong,and the tensile cracks could pass through some smaller WCgrains. 相似文献
59.
60.
Electrochemical study of the corrosion behavior of Ce sealing of anodized 2024 aluminum alloy 总被引:2,自引:0,他引:2
The technological process of Ce sealing of anodized LY12 (2024) alloy is introduced in this paper. The corrosion behavior of the film is studied by polarization curves and electrochemical impedance spectroscopy. The results show that the coating remains passive at the potential range from the open circuit potential (−780 mV) to −250 mV. After immersing the sample in NaCl solution for 6 days, the outer layer Ce conversion coating begins to loose its anticorrosive property. The inner Ce sealing anodized film is not corroded until 60 days immersion. Thus, the inner layer Ce sealing anodized film takes the leading role of the corrosion protection for LY12 alloy. 相似文献