Lithium intercalation mechanism for β-SnSb in Sn-Sb thin films

Based on the first-principles plane wave pseudo-potential method, the electronic structure and electrochemical performance of Li_xSn₄Sb₄ (x=2, 4, 6, and 8) and Li_xSn_1-xSb₄ (x=9, 10, 11, and 12) phases were calculated. A Sn-Sb thin film on a Cu foil was also prepared by radio frequency magnetron sputtering. The surface morphology, composition, and lithium intercalation/extraction behavior of the fabricated film were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). Lithium atoms can easily insert into and extract out of the β-SnSb cell due to the low lithium intercalation formation energy. It is found that lithium atoms first occupy the interstitial sites, and then Sn atoms at the lattice positions are replaced by excessive lithium. The dissociative Sn atoms continue to produce different Li-Sn phases, which will affect the electrode stability and lead to the undesirable effect due to their large volume expansion ratio. The calculated lithium intercalation potential is stable at about 0.7 V, which is consistent with the experimental result.     

Effect of Co on the martensitic transformation,crystal structure and magnetization of Ni<Subscript>52.5</Subscript>Mn<Subscript>23.5</Subscript>Ga<Subscript>24</Subscript> based ferromagnetic shape memory alloys

Five(Ni52.5Mn23.5Ga24)100-xCox(x = 0,2,4,6,8) alloys were prepared by arc melting,and the effects of Co addition on the martensitic phase transformation,crystal structure and magnetization were investigated.The phase transformation temperatures Ms,Mf,As and Af are proportional to the content of Co in the(Ni52.5Mn23.5Ga24)100-xCox alloys,which appears to be due to the variation in the valance electron concentration.The Curie temperature is sensitive to the composition of the alloy.As the amount of Co changes,both the Co-Mn exchange interaction and the distance between Mn atoms change.These,in turn,affect the Curie temperature and magnetization behavior of the alloy.The martensite phases in all the alloys are domained in three different orientations,the domain boundary was determined to belong to the family of {112} lattice planes.     

Effects of yttrium on the formation and magnetic properties of bulk metallic glassy (Fe,Co)-B-Si-Nb alloys

The bulk metallic glassy (BMG) rods of [(Fe_0.5Co_0.5)_0.72B_0.192Si_0.048Nb_0.04]_100-xY_x (x=0-6) and [(Fe_xCo_1-x)_0.72B_0.192Si_0.048Nb_0.04]₉₆Y₄ (x=0.5-0.8) were prepared by copper mold casting. The structure, thermal stability, and magnetic properties of the samples were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometer (VSM). Adding 1at% to 6at% of yttrium, the bulk glassy alloy rods of [(Fe_0.5Co_0.5)_0.72B_0.192Si_0.048Nb_0.04]_100-xY_x(x=0-6) with the diameter of 3 mm were not formed, and the sample with 4at% of yttrium showed less crystalline phase than others. When the Fe/Co atomic ratio was between 5:5 and 7:3, the bulk glassy alloy rods of [(Fe_1-xCo_x)_0.72B_0.192Si_0.048Nb_0.04]₉₆Y₄ (x=0.5-0.8) with the diameter of 2 mm were fabricated. In the (Fe, Co)-B-Si-Nb-Y BMGs, when the Fe content increased, the thermal stability, the supercooled liquid region, and the glass-forming ability (GFA) decreased, but the saturation magnetization (M_s) increased.     

The Distribution of a CP-asymmetric quantity in the decay channel J / Ψ → π + π ? π 0

The distribution of a CP-asymmetric quantityA in the decay channelJ/ψ→π ⁺ π ⁻ π ⁰ is investigated. This dimensionless quantityA is constructed from the momenta of the π-meson final states, namely A=P _x ^{π +} P _y ^{π −} -P _x ^{π −} P _y ^{π −}, whereP _h,P _x ^h andP _y ^h are the module of the momentum of a hadron h, the x- and y-components of that momentum respectively, theJ/ψ particle is produced by e⁺ e⁻ collision, and the direction of the momentum of e⁺ is taken to be the positive direction ofz axis. There would exists the violation under the combined transformation of charge conjugation and space reflection (CP violation) when the average ofA among a lot of events, 〈A〉, be examined to be nonzero clearly from data. In this way, 748 events are selected from the BES experimental data, and analyzed. The corresponding averageA-value is measured to be 〈A〉 = 0.010 39 ± 0.014 61 ± 0.015 2. Further, some discussion of our result, the size of the data sample being need for further attempt and a possible perspective are given.     

Magnetoelectric and converse magnetoelectric res ponses in TbxDy1-xFe2-y alloy ＆ Pb（Mg1/3Nb2/3）（1-x）TixO3 crystal laminated composites

Measured results of magnetoelectric （ME） and converse magnetoelectric （CME） effects of TbxDy1-xFe2-y/ Pb（Mg1/3Nb2/3）（1-x）TixO3/TbxDy1-xFe2-y （TD/PMNT/TD） and PMNT/TD/PMNT laminated composites are presented. ME effect was determined by measuring laminate voltage output under a Helmholtz-generated AC field biased by a DC field （0-1 kOe） （1Oe = 79.58 A/m）. The CME effect was measured by recording the voltage induced in a solenoid encompassing the ME sample while exposed to a DC bias field and PMNT layer driven by a 10 V AC source. The ME and CME responses in the two laminated structure are linear. The highest values of ME coefficients in TD/PMNT/TD and PMNT/TD/PMNT composites are 384 mV/Oe and 158 mV/Oe, respectively, while the highest values of CME coefficients in the two composites are 118 mG/V and 162 mG/V （1 G=10^-4 T）, respectively.     

Crystal structure and negative thermal expansion of solid solution Lu<Subscript>2</Subscript>W<Subscript>3−<Emphasis Type="Italic">x</Emphasis></Subscript>Mo<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>12</Subscript>

A new series of solid solutions Lu₂W_3−x Mo _x O₁₂ (0.5≤x≤2.5) were successfully synthesized by the solid-state method. Their crystal structure and negative thermal expansion properties were studied using high-temperature X-ray powder diffraction and the Rietveld method. All samples of rare-earth tungstates and molybdates are found to crystallize in the same orthorhombic structure with space group Pnca and show the negative thermal expansion phenomena related to transverse vibration of bridging oxygen atoms in the structure. Thermal expansion coefficients (TEC) of Lu₂W_3−x Mo _x O₁₂ are determined as −20.0×10⁻⁶ K⁻¹ for x=0.5 and −16.1×10⁻⁶ K⁻¹ for x=2.5 but -18.6×10⁻⁶ and −16.9×10⁻⁶ K⁻¹ for unsubstituted Lu₂W₃O₁₂ and Lu₂Mo₃O₁₂ in the identical temperature range of 200 to 800°C. High-temperature X-ray diffraction (XRD) data and bond length analysis suggest that the difference between W-O and Mo-O bond is responsible for the change of TECs after the element substitution in this series of solid solutions.     

Preparation and thermal stability of Pd<Subscript>40.5</Subscript>Ni<Subscript>40.5</Subscript>Si<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript>19−<Emphasis Type="Italic">x</Emphasis></Subscript> bulk metallic glasses

With the addition of Si to replace some P, Pd_40.5Ni_40.5Si _x P_19−x (x=0, 2.5, 5, 9.5, 14, and 19 in atomic number fraction) bulk glassy samples with the diameter of about 5 mm were successfully prepared by use of flux treatment and water quenching technology. With the increase of Si content, the glass forming ability of Pd_40.5Ni_40.5Si _x P_19−x increases first for low Si content and then decreases for high Si content (Si≥9.5at%). The Pd_40.5Ni_40.5Si ₅ P₁₄ glassy alloy possesses the largest supercooled liquid region ΔT of 119 K, the largest reduced glass transition temperature of 0.621, and the largest γ parameter of 0.460, indicating that this glassy alloy possesses very large glass forming ability and very high thermal stability.     

Surface tension and specific heat of liquid Ni<Subscript>70.2</Subscript>Si<Subscript>29.8</Subscript> alloy

The thermophysical properties of liquid alloys in me-tastable state are of importance for liquid-solid phase transformation under nonequilibrium conditions[1―10]. Sur-face tension and specific heat, two of the most important thermophysical properties, have significant influences on the process of crystal nucleation and growth. Furthermore, it is necessary to obtain these data so as to perform quan-titative research on rapid solidification[3―10]. The tradi-tional measurement methods, however,…     

Nd<Subscript>2</Subscript>Fe<Subscript>17</Subscript> nanograins effect on the coercivity of HDDR NdFeB magnets with low boron content

Relationships between the coercivity of hydrogenation disproportionation desorption recombination (HDDR) Nd_12.5Fe_81.5−x Co₆B _x bonded magnets and boron content were investigated. Nd₂Fe₁₇ phase with planar magnetic anisotropy is present in the microstructure when x= 4at%–5.88at%, which does not reduce the coercivity of the bonded magnets. High-resolution transmission electron microscopy (TEM) images show that Nd₂Fe₁₇ phase exists in the form of nanocrystals in the Nd2Fe14B matrix. There is an exchange-coupling interaction between the two phases so that the coercivity of HDDR Nd_12.5Fe_81.5−x Co₆B _x bonded magnets is hardly reduced with a decrease in boron content.     

TFEL of Ce3+ in zine sulpho-oxide

A new TFEL material ZnS_xO_1−x: Ce³⁺ is prepared. The EL brightness of ZnS_xO_1−x: Ce³⁺ is at least one order higher than that of ZnS: Ce³⁺ at the same doping concentration of Ce³⁺. The EL emission wavelength of ZnS_xO_1−x: Ce³⁺ (X = 0.5) ranges from 400 to 600 nm. The emission of ZnS_xO_1−x: Ce³⁺ may be used as the blue part of white TFEL.     

Integral Points on a Class of Elliptic Curve

0 IntroductionZasegairerc[h1]fodre sbcirgibientde gsreavle rpaolin tmse tohnocdsert waihnicehlli ppetircm citur ovnese btyogiving the upper bound of solution. Unfortunately,this upperbound was verylarge andsometi mes beyondthe range of com-puter searching.For a particular elliptic curvey2=x3-30x+133(1)he mentioned he can find all integral points and the largestpoint is (x,y) =(5 143 326 ,±11 664 498 677) by using Mas-ser and W櫣stholz bounds on elliptic logarithms .Although recent results on…     

Preparation and characterization of highly active nanosized strontium-doped lanthanum cobaltate catalysts with high surface areas

The volatile organic compounds (VOCs) emitted from the sources of industries are a kind of main pol-lutants to the atmosphere. The Environmental Protec-tion Agency (EPA) of the United States lists more than 300 VOC pollutants. 70% of the toxic compounds t…     

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.     

Synergistically optimizing electrical and thermal transport properties of ntype PbSe

In this paper,we report that the thermoelectric performance of n-type Pb Se could be improved through synergistically optimizing electrical and thermal transport properties via Sb doping and Mg alloying.The carrier concentration was firstly optimized through Sb doping,resulting in a maximum power factor of~15.4μW cm~(-1)K~(-2)and maximum ZT of~0.9 at 873 K in Pb_(0.99)Sb_(0.01)Se.Then,Mg was selected for alloying in Pb sites to produce point defects,which can largely intensify the phonon scattering and lower thermal conductivity.After Mg alloying,the thermal conductivity at 300 K(873 K)was significantly suppressed from~4.6 Wm~(-1)K~(-1)(1.5 Wm~(-1)K~(-1))for Pb_(0.99)Sb_(0.01)Se to~2.9 Wm~(-1)K~(-1)(1.1 Wm~(-1)K~(-1))for Pb_(0.99)Sb_(0.01)Se-6%Mg Se.Through combining Sb doping and Mg alloying,a maximum ZT of~1.1 was achieved at 873 K for Pb_(0.99)Sb_(0.01)Se-6%Mg Se,and the average ZT(ZT_(ave))was increased by 28.6%from~0.42 for Pb_(0.99)Sb_(0.01)Se to~0.54 for Pb_(0.99)Sb_(0.01)Se-6%Mg Se.The results indicate that Pb Se is a robust candidate for medium-temperature thermoelectric applications.     

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)     

Photoluminescence from Si-based SiNxOy films

B⁺, C⁺, Si⁺, and As⁺ with dose of 5 × 10¹⁶ cm⁻² were implanted into SiN_xO_y, films grown on crystalline silicon by plasma-enhanced chemical vapor deposition. The ion-implanted samples exhibit their photoluminescence with different intensities and different peak wavelengths after thermal annealing. Especially, the C⁺-implanted SiN_xO_y, films show very intense photoluminescence at green-yellow color region.     

Charge order and spin order of La0.3Ca0.7Mn（1-x）WxO3 system

The colossal magnetoresistance (CMR) effect and charge ordering (CO) phenomenon in perovskite man- ganites have become very important research objects in the field of materials science. The charge ordering (CO) is that, in some materials with specific pro…     

二维1:-5 Lotka-Volterra复四次系统的可线性化条件

本文考虑了如下的一类平面四次复Lotka-Volterra系统的可线性化问题ẋ=x（1-a₃₀x³-a₂₁x²y-a₁₂xy²-a₀₃y³）,ẏ=-y（5-b₃₀x³-b₂₁x²y-b₁₂xy²-b₀₃y³）.该系统为四次齐次多项式扰动下的具有$1:-5$线性项的复Lotka-Volterra系统,给出了该系统可线性化的充分必要条件.     

Dispersion of CoCl2 into γ-Al2O3 studied by positron

Co²⁺/γ-Al₂O₃ samples were prepared by incipient wetness impregnation of γ-Al₂O₃ with different concentration solution of CoCl₂ and dried at 40 °C. We measured the positron lifetime spectra of the samples of different Co²⁺ mass fractions (0%–8.24%) heated at different temperatures (100–500°C). All lifetime spectra were resolved into four components, in which the third and the fourth components were related to the surface state of the micropores and the secondary pores of the γ-Al₂O₃. The experimental results showed that the Co²⁺ was mainly located in the micropores and the secondary pores near to the exterior of the support. For low Co²⁺ mass fraction samples, when the heating temperature was above 400 °C, dispersal was almost finished. When the Co²⁺ mass fraction was above 5.59%, Co²⁺ and Cl⁻ were dispersed into the secondary pores in the form of multiple layers.