Journal of Alloys and Compounds
Motivated by the ion migration mechanism proposed by David et al. [J. Am. Chem. Soc. 129 (2007) 1594-1601], we mechanically mill the Li3N/Co powder mixture to obtain defective Li3N-type structure with enhanced Li+ mobility. Compared with Li3N the hydrogen storage property of such defective phase is markedly improved, presumably due to the ion-migration-enhancing effect from the incorporation of Co and Fe (from milling utensils). During subsequent cycling, however, this effect cannot persist due to the precipitation of Co-Fe alloy upon hydrogenation. The close correlation between Co-Fe incorporation/precipitation and property variation of Li3N hydrogen storage material provides a preliminary evidence to support the ion migration mechanism. (C) 2007 Elsevier B.V. All rights reserved.
关键词:
Hydrogen absorbing materials;Nitride materials;hydrogen-storage;lithium amide;mechanism;nitride;batteries;mixtures;hydride;imides;linh2;anode
Journal of the American Ceramic Society
Search for new thermal barrier materials with high-temperature stability is very difficult because there are intractable choices among thousands of possible candidates. The present paper shows that identifying and developing new low thermal conductivity materials can be accomplished by first-principles calculations of equilibrium crystal structure and elasticity, and thereafter making theoretical prediction of minimum high-temperature lattice thermal conductivity basing on David Clarke's method for insulating materials. We highlight a new oxynitride ceramic, Y4Si2O7N2, with a low theoretical minimum thermal conductivity of 1.12 similar to W center dot m-1 center dot K-1. The theoretical result is further validated by experimental measurement of thermal conductivity of dense and bulk Y4Si2O7N2. The experimental thermal conductivity is 1.50 similar to W center dot m-1 center dot K-1 at 1300 similar to K. Furthermore, thermal properties of Y4Si2O7N2 are investigated for evaluating its potential performances.
关键词:
theoretical elastic stiffness;barrier coatings;mechanical-properties;gas;gamma-y2si2o7;crystal;y2sio5;system;phase;si3n4-sio2-y2o3
Y.B. Hou
金属学报(英文版)
In this paper, the PMMA films doped with N,N'-diphenyl-N,N'-di(m-tolyl)-benzidineand rubrene were fabricated by spin coating, and the effect of photooxidation onthe photoluminescence of the doped PMMA thin films was investigated. The resultsshowed that under the irradiation of 350nm UV light, N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine can sensitized rubrene and results in the enhancement in the photooxrationof rubrene. The effect of photooxidation on the photoluminescence from rubrene w asmore obvious. Both lifetime measurement and in situ measurement of photolumines-cence showed that rubrene molecules exist in two chemical surroundings.
关键词:
photoluminescence
,
null
Ceramics International
The dispersion behavior of Si3N4 nanopowders prepared by laser-induced gas-phase reaction in a non-aqueous solvent, N-N-dimethylformamide (DNIF) was studied, and triethanolamine (TEA) was selected as a dispersant. One hundred and sixty-six-day sedimentation tests were used to study the stability of the suspensions. Photon correlation spectroscopy was employed to measure the sizes of aggregates and coagulation rates. TEA was proved an effective dispersant for nano-Si3N4 in DMF, presoaking treatment could enhance the effect of the dispersant. TEA 1.0 wt.% referred to Si3N4 and a 1-month-presoaking gave the best dispersion, the dispersion stability was improved from several minutes to several months, and the average size of the aggregates was reduced to about a twenty-fifth. The dispersion ability of TEA was believed being related to its strong affinities both to the powder surface and to the solvent. (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.
关键词:
Si3N4;dispersion;nanopowders;N-N-dimethylformamide;triethanolamine;composite;powders
Journal of Magnetism and Magnetic Materials
We present first-principles study on the magnetic properties of the 3D metal-ligand coordination polymer [Cu(mal)(DMF)]n within the framework of density functional theory ( DFT) by using the full-potential linearized augmented plane-wave (FP-LAPW) method. The total and partial density of states ( DOS), the band structure, and the atomic spin magnetic moment of [ Cu( mal)( DMF)] n are calculated. The calculation reveals that [ Cu( mal)( DMF)] n is a ferromagnetic semiconductor. The calculated spin magnetic moment is about 1.000 mu B per molecule, which is in agreement with experimental value. (c) 2007 Elsevier B.V. All rights reserved.
关键词:
first-principles;electronic structure;ferromagnetic properties;complexes;acid
柴生勇
,
安忠维
液晶与显示
doi:10.3969/j.issn.1007-2780.2001.02.007
通过Ulmann缩合反应合成了在有机电致发光（OEL）显示器件上有使用前景的四苯基联苯二胺类空穴传输材料N， N′-二苯基-N， N′-双(3-甲基苯基)-［1， 1′-联苯］-4， 4′-二胺、 N， N′-二苯基-N， N′-双(4-甲基苯基)-［1， 1′-联苯］-4， 4′-二胺和N， N， N′， N′-四苯基-［1， 1′-联苯］-4， 4′-二胺。 对产品从混合物中分离的方法作了改进。 其产率及含量分别为85%、 97.6%； 95%、 98.5%； 70 %、 98.1% 。 对3种化合物均用红外光谱进行了表征。
关键词:
制备
,
四苯基二胺化合物
,
空穴传输材料
,
有机电致发光
