Dead lithium phase investigation of Sn-Zn alloy as anode materials for lithium ion battery

In this work, based on First-principle plane wave pseudo-potential method, we have carried out an in-depth study on the possible dead lithium phase of Sn-Zn alloy as anode materials for lithium ion batteries. Through investigation, we found that the phases Li_xSn₄Zn₄(x = 2, 4, 6, 8) contributed to reversible capacity, while the phases Li_xSn₄Zn_8−(x−4)(x = 4.74, 7.72) led to capacity loss due to high formation energy, namely, they were the dead lithium phases during the charge/discharge process. And we come up with a new idea that stable lithium alloy phase with high lithiation formation energy (dead lithium phase) can also result in high loss of active lithium ion, besides the traditional expression that the formation of solid electrolyte interface film leads to high capacity loss. Supported by the National Natural Science Foundation of China (Grant No. 50771046), Natural Science Foundation of Guangdong Province (Grant No. 05200534), Key Projects of Guangdong Province and Guangzhou City (Grant Nos. 2006A10704003 and 2006Z3-D2031) and China Postdoctoral Science Foundation (Project No. 20080440764)     

Low temperature thermodynamic study of the stable and metastable phases of vanadium

The low temperature thermodynamics of the stable phase of vanadium has been assessed by the polynomial and Debye models from the experimental data available in literature. By means of the con-strained nonlinear least squares curve fitting arithmetic,two sets of parameter values have been de-termined. Expressions of the thermodynamic functions Cp(T) and G(T)-H(298.15 K) at 0―298.15 K are presented. The low temperature thermodynamics of the metastable phase of vanadium can only be extrapolated by the Debye model. The expression of the thermodynamic function Cp(T) at 0―298.15 K is presented.     

Formation of ζ phase in Cu-Ge peritectic alloys

Rapid growth behavior of ζ phase has been investigated in the undercooling experiments of Cu-14%Ge, Cu-15%Ge, Cu-18.5%Ge and Cu-22%Ge alloys. Alloys of the four compositions obtain the maximum undercoolings of 202 K（0.17TL）, 245 K（0.20TL）, 223 K（0.20TL） and 176 K（0.17TL）, respectively. As the content of Ge increases, the microstructural transition of ＂a（Cu） dendrite ＋ ζ＂ peritectic phase → ζ＂ peritectic phase →, ζ dendrite ＋ （ε＋ζ） eutectic＂ takes place in the alloy at small undercooling, while the microstructural transition of ＂fragmented α （Cu）dendrite ＋ ζ peritectic phase →, ζ peritectic phase →ζ dendrite ＋ ε phase＂ happens in the alloy at large undercooling. EDS analysis of the Ge content in peritectic phase indicates that undercooling enlarges the solid solubility of ζ rdendrite, which leads to a decrease in the Ge content in ζ phase as undercooling increases. In the Cu-18.5%Ge alloy composed of ζ peritectic phase, the Ge content in ζ phase increases when undercooling increases, which is due to the restraint of the Ge enrichment on the grain boundaries by high undercooling effect.     

Rapid solidification of undercooled Al-Cu-Si eutectic alloys

Under the conventional solidification condition, a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work, rapid solidification of an undercooled liquid Al_80.4Cu_13.6Si₆ ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating. The relationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt. The maximum undercooling is 147 K (0.18T _E). The undercooled ternary eutectic is composed of α(Al) solid solution, (Si) semiconductor and θ(CuAl₂) intermetallic compound. In the (Al+Si+θ) ternary eutectic, (Si) faceted phase grows independently, while (Al) and θ non-faceted phases grow cooperatively in the lamellar mode. When undercooling is small, only (Al) solid solution forms as the leading phase. Once undercooling exceeds 73 K, (Si) phase nucleates firstly and grows as the primary phase. The alloy microstructure consists of primary (Al) dendrite, (Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling, while at large undercooling primary (Si) block, (Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic coexist. As undercooling increases, the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases. Supported by the National Natural Science Foundation of China (Grant Nos. 50121101, 50395105) and the Doctorate Foundation of Northwestern Polytechnical University (Grant No. CX200419)     

Phase field simulation of monotectic transformation for liquid Ni-Cu-Pb alloys

Based on the subregular solution model, the liquid phase separation of ternary (Ni _x Cu_100−x )₅₀Pb₅₀ monotectic alloys is simulated by the phase field method. It is found that if the surface segregation potential is not incorporated, the dynamic morphologies of alloy melt show a transition from disperse microstructure into bicontinuous microstructure with the increase of fluidity parameter. When the surface segregation potential is coupled, Pb-rich phase migrates preferentially to the surface of the liquid alloy, and the Ni-rich phase depends on the Pb-rich phase to nucleate. With the extension of the phase separation time, the surface layer is formed through coagulation and growth, and its thickness gradually increases. The Ni-rich phase migrates to the central part, and finally a two-layer core-shell microstructure is produced. The concentration in the surface layer fluctuates more conspicuously than that inside the bulk phase, which subsequently transfers from the surface to the interior by a wave. The fluid field near the liquid-liquid interface is strong at the beginning of phase separation, and reduces later on. The surface segregation is essential to the formation of the surface layer, concentration profile variation, fluid field distribution and phase separation morphology. Supported by the National Natural Science Foundation of China (Grant Nos. 50121101, 50395105)     

Compression behavior and equation of state of Ni77P23 amorphous alloy

The compression behavior of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using insitu high pressure energy dispersive X-ray diffraction with a syn- chrotron radiation source. The equation of state is determined by fitting the experimental data accord- ing to Birch-Murnaghan equation: -ΔV/V0=0.08606P-3.2×10-4P2 5.7×10-6P3. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa.     

Effects of the dispersed droplet sizes on the critical behavior of pseudobinary microemulsion

The critical behavior of pseudobinary microemulsion systems{water/sodium di(2-ethylhexyl)sulfo- succinate(AOT)/n-decane}with various droplet sizes was studied by measurements of refractive index. It was found that the critical exponentsβfor all systems approach 0.327 in a region sufficiently close to the critical temperature,which is consistent with 3D-Ising universality class.The critical temperatures linearly decrease as the dispersed droplet sizes increase.The critical amplitude almost linearly in- creases with increasing the dispersed droplet sizes.     

Low-field positive and high-field negative magnetoresistances in multiphase Fe-oxide thin films at room temperature

Multiphase Fe-oxide thin films are fabricated on glass substrates by a facing-target sputtering tech- nique. X-ray diffraction and X-ray photoelectron spectroscopy reveal that Fe, Fe3BO4, γ -Fe2BO3B and FeO coexist in the films. High resolution transmission electron microscopy shows the well-defined colum- nar grain structure with the unoxidized Fe as the core and iron-oxide as the shell. The low-field positive and high-field negative magnetoresistances coexist in such a system at room temperature, which can be explained by considering a shell/core model. Nonlinear current-voltage curve and photovoltaic effect further confirm the tunneling-type conduction.     

Peritectic solidification under high undercooling conditions

The solidification characteristics of highly undercooled Cu-7.77%Co peritectic alloy has been examined by glass fluxing technique. The obtained undercoolings vary from 93 to 203 K(0.14 TL). It is found that the α(Co) phase always nucleates and grows preferentially, which is followed by peritectic transformation. This means that the peritectic phase cannot form directly, even though the alloy melt is undercooled to a temperature far below its peritectic point. The maximum recalescence temperature measured experimentally decreases as undercooling increases , which is lower than the thermodynamic calculation result owing to the actual non-adia-batic nature of recalescence process. The dendritic fragmentation of primary α(Co) phase induced by high undercooling is found to enhance the completion of peritectic transformation. In addition, the LKT/BCT dendrite growth model is modified in order to make it applicable to those binary alloy systems with seriously curved liquidus and solidus lines. The dendrite growth velocities of primary α(Co) phase are subsequently calculated as a function of undercooling on the basis of this model.     

Entropy as a selection rule for crystal growth in undercooled binary eutectic melts

A solution entropy model was developed for the undercooled binary eutectic alloy systems. As an extension of Taylor and Fidler et al.’s model, the present model considered the change of phase composition with the increase of undercooling. Furthermore, the sub-regular solution model and the interaction parameter (I _AB ) were also introduced. In this paper, the extended model is used to calculate the solution entropy for binary eutectic phases under the undercooled condition, and the application scope of the model is also extended. Not only the growth manner of eutectic phases, but also the transition of morphologies may be predicted and explained by calculating the solution entropy of eutectic phases under the non-equilibrium condition with the developed model. Experimental results show that the developed model is valid for the undercooled Ni-Si and Ni-Sn eutectic alloy systems. Supported by the National Natural Science Foundation of China (Grant No. 50395103) and Doctorate Foundation of Northwestern Polytechnical University (Grant No. CX200506)     

Composition dependence of viscosity for Al（1-x）Mgx（0≤x≤0. 10） alloys

Viscosities of molten Al（1-x）Mgx（0≤x≤0. 10 alloys have been measured in the temperature range of 973 K--1173 K by a torsional oscillation cup method. The viscosity dependence on temperature for Al（1-x）Mgx（0≤x≤0. 10 melts obeys Arrhenius equation. The viscosity increases with increasing magnesium concentration in the investigated system. There is an important relationship between viscosity and its glass-forming ability for metallic melt.     

Enolate chelating N-heterocyclic carbene complexes of Fe(II): Synthesis, structure and their catalytic activity for ring-opening polymerization of ε-caprolactone

The reaction of anhydrous FeBr2 with two equivalents of anionic N-heterocyclic carbene (NaL1 and NaL2), which are generated in situ by the reaction of the corresponding salt [4-R-C6H4COCH2{CH- (NCHCHNiPr)}Br] (R = OCH3, H2L1Br, 1; R = F, H2L2Br, 2) with two equivalents of NaN(SiMe3)2, affords bis-ligand Fe(II) complexes of L12Fe (3) and L22Fe (4) in high yield, respectively. Attempt to synthesize mono-ligand Fe(II) bromide by the 1:1 molar ratio of NaL to FeBr2 is unsuccessful, and the same com- plexes of 3 and 4 were obtained. Both 3 and 4 have been depicted by elemental analysis and X-ray structure determination. Preliminary studies show that both 3 and 4 can be used as single-component catalyst for the ring-opening polymerization of ε-caprolactone, and the catalytic activity of 3 is higher than that of 4.     

High undercooling and rapid dendritic growth of Cu-Sb alloy in drop tube

Droplets of Cu-20%Sb hypoeutectic alloy has been rapidly solidified in drop tube within the containerless condition. With the decrease of droplet diameter, undercooling increases and the microstructures of primary copper dendrite refines. Undercooling up to 207 K (0.17 T _L) is obtained in experiment. Theoretic analysis indicated that because of the broad temperature range of solidification, the rapid growth of primary copper dendrite is controlled by the solutal diffusion. Judging from the calculation of T₀ curve in the phase diagram, it is shown that the critical undercooling of segregationless solidification is δT ₀ = 474 K. At the maximum undercooling of 207 K, the growth velocity of primary copper phase exceeds to 37 mm/s, and the distinct solute trapping occurs.     

Investigation on the key factors in the hydrothermal synthesis of BN： The way of introducing sodium azide

The way of introducing sodium azide (NaN_3) into the reaction solution played an important role in the preparation of cBN by hydrothermal synthesis method. The results showed that both cBN content and crystalline perfection of the samples improved with increasing R_N value, and pure cBN could be obtained at 300℃ and 10 MPa when R_N increased to 3:1. Here R_N is defined as R_N =NaN_3(I)/NaN_3(II), wherNaN_3(I) denotes the amount of NaN_3 (in molar) that is added into the autoclave at the beginning of threaction process, and NaN_3(II) is the amount of NaN_3 (also in molar) introduced into the autoclave ahigh temperature and high pressure (i.e. 300℃ and 10 MPa). In order to explain the experimental results, a preliminary model was proposed in this paper.     

Styrene polymerization catalyzed by nickel complexes bearing hydroxyindanone-iminate ligands

Activated by methylaluminoxane, mononuclear bis（hydroxyindanone-iminate）nickel complexes Ni[ArN=CC2H3（CH3）C6H2（R）O]2 （Ar = 2,6-i-Pr2C6H3, R=Me（1）, R=CI（2）, and R=H（3）） showed good activity for the styrene polymerization. The effect of many reaction parameters including the AI/Ni ratio, temperature, and reaction time on catalytic activities of catalytic systems and the molecular weights of the obrained polystyrene was ascertained. The highest activity of 1.34×10^5g（PS）·mol^-1（Ni）·h^-1 was obtained under the optimum reaction condition. The ^13C NMR spectra of the polymers revealed that the polymer was isotactic-rich atactic polystyrene. And the coordination mechanism was confirmed by the analyses of the polymer chain end-groups.     

Preparation and characterization of three-dimensionally ordered macroporous polystyrene <Emphasis Type="Italic">via</Emphasis> atom-transfer radical polymerization

Three-dimensionally ordered macroporous polystyrene （3DOM PS） with pore size of 350 nm was fab- ricated using Cp2Co/Ethyl 2-bromoisobutyrate （EBiB） catalytic system by ATRP. The resulting polymers were detected by FT-IR, 1H-NMR, SEM, and GPC. The microstructure of 3DOM PS was confirmed by FT-IR and 1H-NMR. SEM micrographs show that both silica spheres within the templates and pores in the 3DOM polystyrene are arranged in highly ordered fashion, and the shrinkage of the pores in the 3DOM PS is 24%. GPC curves show that the 3DOM PS possesses slightly lower Mn and narrow MWD compared with bulk one. This result indicats that living polymerization is different from non-living polymerizationin in the confined space.     

Giant magneto-optical faraday effect of nanometer Fe-In<Subscript>2</Subscript>O<Subscript>3</Subscript> granular films

The giant magneto-optical Faraday effect of nanometer ferromagnetic metal-semiconductor matrix Fe-ln2O3 granular films prepared by the radio frequency sputtering are studied. The result shows that the Faraday rotation angle θF value of the granular film samples with Fe volume fraction x = 35% is of the order of 10^5（°）/cm at room temperature. Temperature dependence of the Faraday rotation angle θF of Fe0.35（In2O3）0.65 granular films shows that θF value below 10 K increases rapidly with the decrease of the temperature, and when T= 4.2 K, θF value is 106（°）/cm. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that when the temperature decreases to a critical point Tp = 10 K, the transformation of state from ferro-agnetic to spin-glass-like occurs in Fe0.35（In2O3）0.65 granular films. The remarkable increase of the Faraday rotation angle θF value of Fe0.35（In2O3）0.65 granular films below 10 K seems to arise from the sp-d exchange interaction of the granular film samples in the spin-glass-like state.     

Dependence of nitrogen concentration in type Ib diamonds on synthesis temperature

Type Ib diamonds were grown by the temperature gradient method (TGM) at 5.5 GPa and 1500－1560 K in a china-type cubic anvil high pressure apparatus using Ni₇₀Mn₂₅Co₅ alloy as solvent/catalyst. The concentration of nitrogen (C_N) in type Ib diamonds synthesized at different synthesis temperatures was measured by a Fourier transform infrared (FTIR) spectrometer. The dependence of C_N in diamond on synthesis temperature was studied. For the type Ib diamonds synthesized using Ni₇₀Mn₂₅Co₅ as catalyst, its C_N decreases along with the increase of synthesis temperature.     

Structure, magnetic properties and giant magnetostriction studies in [Tb/Fe/Dy] n nano-multilayer film

[Tb/Fe/Dy]_n nano-multilayer films, with precise composition of Tb_0.27Dy_0.73Fe₂, were prepared by the multi-targets magnetron sputtering technique at room temperature (sample A) and 300℃ substrate temperature (sample B). Both of the nano-multilayer films show columnar structures perpendicular to the film plane according to the scanning electron microscopy results. The magnetic hysteresis loops and the giant magnetostriction (GMS) property of the two samples indicate the perpendicular anisotropy in them. In spite of the perpendicular anisotropy, both of the samples present GMS effect. In a very low applied field of 0.18 T, the GMS value in sample B is 89.3 ppm, which is about four times of that in sample A, 23.5 ppm. The good low-field GMS effect in sample B might attribute to the Laves phase of R-Fe₂ segregated from the amorphous matrix under the thermal annealing of the substrate. The relation between the magnetization process and GMS property of the perpendicular anisotropy nano-multilayer films is further investigated.     

Genetic analysis and gene mapping of a narrow leaf mutant in rice ( Oryza sativa L.)

A narrow leaf mutant was obtained after T-DNA transformation conducted on a rice variety Zhonghua 11. Several abnormal morphological characteristics, including semi-dwarf, delayed flowering time, narrow and inward rolling leaves, and lower seed-setting, were observed. The rate of net photosynthesis (under saturate light) of flag leaves in the mutant was significantly lower than that of the wild type. Moreover, the leaf transpiration rate and stomatal conductance in the mutant flag leaf were lower than those of the wild type at the grain filling stage. It was found that the mutant phenotype was not caused by the T-DNA insertion. Genetic analysis showed that the mutant was controlled by a single recessive gene, designated as nal3(t). A genetic linkage map was constructed using a large F₂ mapping population derived from a cross between nal3(t) and an indica variety Longtefu B with 6 polymorphic markers on chromosome 12 identified from 366 SSR markers by the BAS method. Gene nal3(t) was mapped between the markers RM7018 and RM3331. Fine mapping of nal3(t) locus was conducted with 22 newly developed STS markers based on the sequence diversity around the region harboring nal3(t) between Nipponbare and 93–11, and nal3(t) was finally mapped to a 136-kb region between the STS markers NS10 and RH12-8. Supported by National High Technology Research and Development Program of China (863 Program) (Grant No. 2006AA10A102), National Natural Science Foundation of China (Grant No. 30600349) and Natural Science Foundation of Zhejiang Province (Grant No. Y306149)