Authors: Li Min Dong, Yan Li Zhuang, Zhi Dong Han, Ze Wu, Xian You Zhang
Abstract: Green phosphor of La(BO3, PO4): Ce, Tb was synthesized by means of sol-gel method and conventional solid state method. The thermal formation process was characterized by thermogravimetric analysis (TG) and (DTA). The effects of synthesis method and conditions on the crystal and morphological structure were investigated by (XRD) and (SEM). The results revealed that La (BO3, PO4): Ce, Tb phosphors with monocline structure and high purity were successfully prepared by sol-gel method. Compared with solid state method, the products synthesized by sol-gel method presented well developed crystal structure, small particle size, narrow size distribution and high luminescent performances. The product synthesized at 1050°C for 2h had better emission intensity.
359
Authors: Chan Yeol Seo, Xiao Dong Wu, Kiyonori Suzuki
Abstract: It is well known that catalytic additives and mechanical milling are effective in improving hydrogen desorption kinetics of MgH2. In this study, the effect of catalytic additives including BaCa1-xNdxO3-δ (BCN) on the desorption behavior of MgH2 was investigated. It was found that BCN can improve the desorption kinetics, but not as effective as other known additives such as Nb2O5. The effect of milling temperature was also studied. It was found that the cryogenic milling is not as effective as room temperature milling primarily due to the inhomogeneous particle size distribution.
2847
Authors: Li Min Gao, Guang Chuan Liang, Li Wang, Xiao Ke Zhi, Xiao Fei Jie
Abstract: LiFePO4/C powders were synthesized by carbothermal reduction method using Li2CO3 (A.R), FePO4 (A.R) and glucose as raw materials. In this paper, the carbothermal reaction courses were characterized by Thermo-gravimetric (TG)/Differential Thermal Analysis (DTA), X-ray diffraction (XRD) and Fourier transform infrared (FTIR). It was found that the different synthesis temperatures and the different reducing atmosphere in systems could lead to different reactions, resulting in different final products and a direct impact on material performance. At around 350 °C LiFePO4 is directly formed without intermediate phase. In lower temperature of 400-500 °C, the sample included a certain amount of Li3PO4 and Fe2O3 impurity phases. When calcination temperature rose to 550 °C, the sample could be pure LiFePO4 phase.
248
Authors: Li Qin Wang, Xiang Ni Yang, Yang Han, Ning Yu, Xiu Li Zhao
Abstract: The Y/MCM-41 composite molecular sieves were synthesized in the method of hydrothermal crystallization with cetyltrimethylammonium bromide (CTMABr) as the template agent. The as-prepared composite molecular sieves were characterized by the means of X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), the thermogravimetric and differential thermal analysis (TG-DTA) and the nitrogen adsorption test. The experimental results were shown as follows: the Y/MCM-41 composite molecular sieves kept properties of Y-zeolites and MCM-41 molecular sieves. In the XRD and FT-IR spectra, it can be found both characteristic peaks of Y-zeolites and MCM-41 molecular sieves. The pore size distribution plot indicated that the Y/MCM-41composite molecular sieves had micro-mesoporous structure, and the average pore size were about 1.5 nm and 15 nm. The decomposition temperature of the template agent was at 320 °C, and the calcined temperature of Y-zeolites was at about 560 °C. There showed an endothermic process constantly in the DTA curve, and there was little mass loss in the TG curve, indicating the obtained Y/MCM-41 composite molecular sieves had higher thermal stability.
159
Authors: Yi Shan Jiang, Jiang Hua Luo, Zhen Li, Lu Ning Chen
Abstract: Cornstalk fibers were modified with surface modification and the properties of cornstalk fiber/gypsum composites was studied. The results showed that mechanical properties of cornstalk fiber/gypsum composites were enhanced by adding unmodified cornstalk fibers, but composites waterproof performance was decreased greatly. Through surface modification on cornstalk fibers, composites mechanical properties were further enhanced, and composites waterproof performance was improved obviously. The mechanism of surface modification was discussed, and the model of interfacial zone between modified cornstalk fiber and gypsum matrix was proposed.
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