LI Chunzhi WANG Shuncai JIN Yan Institute of Aeronautical Materials
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Beijing
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Laboratory of Atomic Imaging of Solids
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Institute of Metal Research
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Academia Sinica
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Shenyang
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China
金属学报(英文版)
The dispersoid phase Al_(20)Cu_2Mn_3 in a 2024 Al alloy is commonly composed of twins,An ob- servation of corresponding high resolution image shows that the twin boundary plane is a glide plane other than mirror one.Two neighbouring components of twins are not symmetry of re- flection or rotation,but of glide reflection.The“diamond”glide plane is(101)and the glide vector is(1/4)(-).Components of twins in the phase take shape of prism with the longitudinal edge being parallel to[010]and side faces being{101}and{100}.
关键词:
twin
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International Journal of Hydrogen Energy
A systematic investigation on the hydrogen storage properties of Li-Mg-N-H materials with various compositions was performed. Li-Mg-N-H hydrogen storage materials were prepared by mechanically milling LiNH2/MgH2 mixtures with initial molar ratios ranging from 1.5:1 to 3: 1, followed by de/rehydriding at 200 degrees C. It was found that the hydrogen storage capacity of the system was highly dependent on the initial phase ratio of the LiNH2/MgH2 mixture. An optimum hydrogen capacity of about 5 wt% was achieved in the 2.15:1 LiNH2/MgH2 mixture. Different carbon materials, such as the single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes, graphite and activated carbon, were used as additive to improve the hydrogen storage performance. It was found that the dehydriding kinetics of the Li-Mg-N-H material could be markedly improved by adding a small amount of SWNTs, especially in the as-prepared state. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
关键词:
hydrogen storage;dehydriding kinetics;carbon nanotubes;arc-discharge method;system;microstructure;desorption;absorption;behaviors;property;imides
Acta Physica Sinica
A first-principles plane-wave pseudopotential method based on the density functional theory is used to investigate the dehydrogenation properties and the influence mechanism of Li(4)BN(3)H(10) hydrogen storage materials. The binding energy, the density of states and the Mulliken overlap population are calculated. The results show that the binding energy of crystal has no direct correlation with the dehydrogenation ability of (LiM)(4)BN(3)H(10)(M = Ni, Ti, Al, Mg). The width of band gap and the energy level of impurity are key factors to affect the dehydrogenation properties of (LiM)(4)BN(3)H(10) hydrogen storage materials: the wider the energy gap is, the more strongly the electron is bound to the bond, the more difficulty the bond breaks, and the higher wile the dehydrogenation temperature be. Alloying introduces the impurity energy level in band gap, which leads the Fermi level to enter into the conduction band and the bond to be weakened, thereby resulting in the improvement of the dehydrogenation properties of Li(4)BN(3)H(10). It is found from the charge population analysis that the bond strengths of N-H and B-H are weakened by alloying, which improves the dehydrogenation properties of Li(4)BN(3)H(10).
关键词:
hydrogen storage materials;first-principles calculation;element;substitution;dehydrogenation;linh2
Journal of Power Sources
We report a simple strategy to prepare a hybrid of lithium titanate (Li(4)Ti(5)O(12), LTO) nanoparticles well-dispersed on electrical conductive graphene nanosheets as an anode material for high rate lithium ion batteries. Lithium ion transport is facilitated by making pure phase Li(4)Ti(5)O(12) particles in a nanosize to shorten the ion transport path. Electron transport is improved by forming a conductive graphene network throughout the insulating Li(4)Ti(5)O(12) nanoparticles. The charge transfer resistance at the particle/electrolyte interface is reduced from 53.9 Omega to 36.2 Omega and the peak currents measured by a cyclic voltammogram are increased at each scan rate. The difference between charge and discharge plateau potentials becomes much smaller at all discharge rates because of lowered polarization. With 5 wt.% graphene, the hybrid materials deliver a specific capacity of 122 mAh g(-1) even at a very high charge/discharge rate of 30C and exhibit an excellent cycling performance, with the first discharge capacity of 132.2 mAh g(-1) and less than 6% discharge capacity loss over 300 cycles at 20C. The outstanding electrochemical performance and acceptable initial columbic efficiency of the nano-Li(4)Ti(5)O(12)/graphene hybrid with 5 wt.% graphene make it a promising anode material for high rate lithium ion batteries. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
Lithium titanate;Graphene;High rate anode materials;Lithium-ion;batteries;anode material;electrochemical performance;nanocrystalline li4ti5o12;reversible capacity;cyclic performance;spinel li4ti5o12;rate;capability;graphene;composite;insertion
Zhijian LIU
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Zhiyou LI
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Wei DUAN
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Xuanhui QU
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Baiyun HUANG
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Siqi ZHANG
材料科学技术（英文）
A LI-B alloy has been prepared using a pretreated amorphous B powder and pure Li ingot as starting materials by continually slow addition of B powder and intensified stirring in the process of melting. The microstructure and the discharge characteristic of the materials have been investigated. Results show that the problem of temperature control in synthesis would be modified by means of continual addition of B powder, the Li7B6 would be more finery distributed in the metal Li by means of intensified stirring. The discharge characteristic of the Li-B alloy using amorphous B as starting materials is almost the same with that of using crystalline B.
关键词:
Materials Science & Engineering C-Biomimetic Materials Sensors and Systems
The terminology of materials study inspired by biological systems or phenomena is analyzed at first. It is pointed that the term "bio-inspired" may be better than the terms "bionic" or "biomimetic", since the former is relatively easy to be accepted. The new trends of bio-inspired study of structural materials are analyzed in short. Some progress in bio-inspired design and processing of materials in this institute (IMRCAS) are summarized briefly in this talk, such as biomimetic design of worst bonding interface for composites; dumbell-like whiskers simulating animal bone; fractal tree reinforcement by mimicry of branched roots in soil; etc. The possibility of modification and recovery of materials by nonequilibrium bio-inspired treatment are further explored, including the nonequilibrium process under transient heating, dissipative structure and self-organization process of open system, inspiration by living process, influence of high intensive electropulsing on the working Life of materials, a possible way of fatigue recovery of materials and the healing effect of electropulsing in metals. Some tentative practice in biomaterial modification are also studied such as the reformed bamboo reinforced aluminium laminates, etc. A discussion on the methodology of bio-inspired study of materials consists briefly in the last part of the talk. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
bio-inspired;bionic;biomimetic;structural materials;composites
