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1.
采用第一性原理超软赝势平面波方法计算了Sn3InSb4的嵌Li性能,得到各种嵌Li相的嵌Li形成能、理论质量比容量、体积膨胀率、能带结构、态密度和差分电荷密度等.从能量角度分析,Li在嵌入时,优先占据晶胞的四面体间隙位置,然后逐步挤出处于节点位置的Sn原子和In原子.在嵌Li过程中,材料表现出较大的体积膨胀率(11.74%-43.40%),这是导致Sn3InSb4作为Li离子电极材料循环性能差的重要原因.态密度计算表明,体系的导电性能首先随嵌Li量的增加而增加,当所有的间隙位置被Li填满,发生Sn的替换反应时,富Li态合金相的导电性反而下降. 相似文献
2.
Young-Lae Kim Heon-Young Lee Serk-Won Jang Seung-Joo Lee Hong-Koo Baik Young-Soo Yoon Young-Shin Park Sung-Man Lee 《Solid State Ionics》2003,160(3-4):235-240
Thin film Ni3Sn2 anodes were deposited on a Cu substrate by e-beam evaporator at room temperature. The deposited films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). They were tested as anodes for thin film rechargeable lithium batteries. These film electrodes exhibited an excellent cycle performance over 500 cycles. Ni3Sn2 films remained without undergoing any crystallographic phase change during cycling. 相似文献
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Jie ChenZhida Han Bin Qian Ping ZhangDunhui Wang Youwei Du 《Journal of magnetism and magnetic materials》2011,323(2):248-251
The effects of Al substitution on the phase transitions and magnetocaloric effect of Ni43Mn46Sn11−xAlx (x=0-2) ferromagnetic shape memory alloys were investigated by X-ray diffraction and magnetization measurements. With the increase of Al content, the cell volume decreases due to the smaller radius of Al, and the martensitic transformation temperature increases rapidly, while the Curie temperature of austenitic phase shows a small increase. A large positive and a negative magnetic entropy change were observed near the first-order martensitic transition and the second-order magnetic transition, respectively. The magnetic entropy changes, hysteresis behavior, and refrigerant capacity near the two transitions are compared. 相似文献
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NbTi0.5Ni0.5O4 (NTNO) has been prepared using solid state synthesis and investigated as a potential anode material. The oxide form of NTNO has single phase rutile-type structure with tetragonal (P42/mnm) space group. The reduced form is a composite of nano-scaled particles of metallic Ni and Nb1.33Ti0.67O4 phase. Reduced NTNO showed high electronic conductivity up to 280 S.cm− 1 at 900 °C in reducing atmosphere, but suffers from low CTE equal to 3.78 10− 6 K− 1. Studies of NTNO as anode material were carried out in a three electrode - electrochemical half cell configuration under pure humidified H2 at 900 °C using a 2 mm thick zirconia electrolyte and without any additional current collector material. The results show a reasonable series resistance (Rs) equal to 2.7 Ωcm2 (about 50% higher than for metallic gold layers) indicating a good current collection performance for a 10 μm layer of material. The polarization resistance (Rp) was equal to 33 Ωcm2 and is attributed to a poor density of three phase boundaries (TPB) and shortage of oxide ion conduction in the anode layer. The results show the potential of NTNO as an anode material, especially after optimization of the microstructure towards the increase of TPB length. 相似文献
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NiAlxFe2−xO4 and Ni1−yMnyAl0.2Fe1.8O4 ferrites were prepared by the conventional ceramic method and were characterized by X-ray diffraction, scanning electron microscopy, and magnetic measurements. The single spinel phase was confirmed for all prepared samples. A proper explanation of data is possible if the Al3+ ions are assumed to replace Fe3+ ions in the A and B sites simultaneously for NiAlxFe2−xO4 ferrites, and if the Mn2+ ions are assumed to replace Ni2+ ions in the B sites for Ni1−yMnyAl0.2Fe1.8O4 ferrites. Microstructural factors play an important role in the magnetic behavior of Ni1−yMnyAl0.2Fe1.8O4 ferrites with large Mn2+ content. 相似文献
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Detailed electrochemical investigations have been carried out on LiNi0.8Co0.17Al0.03O2 as cathode materials for lithium ion batteries in the potential range of 2.8-4.3 V. This sample showed an initial discharge capacity of 186 mAh/g which corresponds to 67% of its theoretical capacity. The effect of addition of LiCoO2 to LiNi0.8Co0.17Al0.03O2 in the ratio 10:90, 30:70, 50:50 has been studied. The results showed that the addition of LiCoO2 has improved the working voltage of the cell. In addition, the percentage retention (95%) of the cell is significantly increased in the composition ratio 50:50. 相似文献
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Ying-Tang Zhang Zi-Yu Chen Chun-Chang Wang Hui-Bin Lü 《Journal of magnetism and magnetic materials》2009,321(9):1199-1201
Polycrystalline perovskite La0.8Tb0.2MnO3 (LTMO) with an orthorhombic phase was synthesized by conventional solid-state reaction. The magnetic and electric properties of La0.8Tb0.2MnO3 were examined. The striking finding is that the material exhibits giant magnetoresistance at room temperature as high as −31.8% and −35.7% under the low magnetic fields of 100 and 1000 Oe, respectively. This result suggests that La0.8Tb0.2MnO3 has a promising potential in future device developments. 相似文献
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Determination of the magnetocaloric effect associated with martensitic transition in Ni46Cu4Mn38Sn12 and Ni50CoMn34In15 Heusler alloys 下载免费PDF全文
This paper presents a study of the inverse magnetocaloric effect (MCE) corresponding to martensitic transition using various experimental approaches for Ni46Cu4Mn38Sn12 and Ni50CoMn34In15 Heusler alloy. Through heat capacity measurements,it is found that the "giant inverse MCE" upon martensitic transition evaluated by the Maxwell relation in these alloys are unphysical results. This is due to the coexistence of both martensitic and austenitic phases,as well as thermal hysteresis during martensitic transition. However,careful study indicates that the spurious results during martensitic transition can be removed using a Clausius-Clapeyron equation based on magnetization measurements. 相似文献
10.
Electrical resistivity measurements on the alloy Ce(Fe0.8Al0.2)2 as a function of temperature in the range of 1.5 to 300 K shows that the long range magnetic order of the CeFe2 is destroyed and that the spin glass phase appears with a negative coefficient of T3/2. The high residual resistivity is also discussed. 相似文献
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The HfFe6Ge6-type compounds Gd0.8L0.2Mn6Sn6 and Tb0.8L0.2Mn6Sn6 (L = Sc, Y, Lu) have been studied by 119Sn Mössbauer spectroscopy. The values of the apparent quadrupolar splitting clearly evidence the easy plane magnetization of the gadolinium compounds and the easy axis one in the terbium compounds. The three tin sites behave differently with the nature and size of the substituting L element. For a given series, the hyperfine field of the Sn2d site is almost unchanged whatever the size of the L element. The hyperfine field of the Sn2e site strongly varies with the L size in relation with atomic displacements. The hyperfine field of the Sn2c site exhibits a more complicated behavior. The field difference in the easy plane and easy axis compounds confirms the angle-dependent anisotropic contribution of the Mn moment to the hyperfine field. The analysis of the results also suggests the play of angle-dependent contributions arising from the rare earth moment. 相似文献
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Nanocomposite of hard (BaFe12O19)/soft ferrite (Ni0.8Zn0.2Fe2O4) have been prepared by the sol–gel process. The nanocomposite ferrite are formed when the calcining temperature is above 800 °C. It is found that the magnetic properties strongly depend on the presintering treatment and calcining temperature. The “bee waist” type hysteresis loops for samples disappear when the presintering temperature is 400 °C and the calcination temperature reaches 1100 °C owing to the exchange-coupling interaction. The remanence of BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite with the mass ratio of 5:1 is higher than a single phase ferrite. The specific saturation magnetization, remanence magnetization and coercivity are 63 emu/g, 36 emu/g and 2750 G, respectively. The exchange-coupling interaction in the BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite is discussed. 相似文献
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Spinel lithium titanate (Li4Ti5O12) as novel anode material for room-temperature sodium-ion battery 下载免费PDF全文
This is the first time that a novel anode material, spinel Li4Ti5O12 which is well known as a “zero-strain” anode material for lithium storage, has been introduced for sodium-ion battery. The Li4Ti5O12 shows an average Na storage voltage of about 1.0 V and a reversible capacity of about 145 mAh/g, thereby making it a promising anode for sodium-ion battery. Ex-situ X-ray diffraction (XRD) is used to investigate the structure change in the Na insertion/deinsertion process. Based on this, a possible Na storage mechanism is proposed. 相似文献
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Dense composites were prepared through incorporating the dispersed Ni0.8Zn0.2Fe2O4 ferromagnetic particles into Sr0.5Ba0.5Nb2O6 ferroelectric matrix. Extrinsic dielectric relaxation and associated high permittivities of the materials are reported in the composites. We used an ideal equivalent circuit to explain electrical responses in impedance formalism. A Debye-like relaxation in the permittivity formalism was also found. Interestingly, real permittivity (ε′) of the sample containing 30% Ni0.8Zn0.2Fe2O4 shows obvious independence of the temperature at 100 kHz. Dielectric relaxation and high-ε′ properties of the composites are explained in terms of the Maxwell-Wagner (MW) polarization model. 相似文献
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Polycrystalline ceramic samples of Bi2Sn2−xTixO7 (x=0.00, 0.2, 0.4, 0.6 and 0.8) have been synthesized by standard high temperature solid state reaction method. The effect of homovalent cation (titanium) substitution on the Sn-site on the structural and electrical properties of the pure Bi2Sn2O7 ceramic have been studied by X-ray diffraction followed by SEM, dielectric and dc conductivity studies. The structural analysis indicates that the increase of titanium contents do not lead to any secondary phase. The frequency and temperature dependent dielectric studies have been carried out. It is found that the Ti doping reduces the material particle size. The size of the particles are strongly influenced by the addition of titanium to the system. The substitution of Ti for Sn ions affected the degree of disorder and modified the dielectric properties leading to more resistive ceramic compounds. The activation energies of all the compounds were calculated using the relation σ=σ0exp(−Ea/kT). 相似文献
17.
研究了Zr65Cu17.5Ni10Al7.5合金定向凝固过程中组织形态的演变特征,探索了不同的凝固方向与重力场方向间的相互取向关系对凝固组织形态的影响.存在着一个临界抽拉速度Vfc,当抽拉速度大于该临界值时组织方向性变差.该合金本身的物理性质决定了它具有一个较小的临界值(Vfc=5mm/min).不同的凝固方向与重力场的相对取向关系改变了液-固界面前沿的浮力对流状态.当凝固方
关键词: 相似文献
18.
A thin-film lithium phosphorous oxynitride (LiPON) layer on the top of a graphite anode is synthesized via radio frequency magnetron sputtering, whereas the thickness of the film is about 0.3 ~ 1.3 μm. The field emission scanning electron microscopy on the samples confirms the even-coated layer on the anode, while the thickness of layer is reconfirmed by weighing the area density of sputtered anode. The storage experiment at elevated temperature of LiNi0.8Co0.15Al0.05O2/graphite cells with and without a LiPON layer on anode reveals that the LiPON layer on the anode would restrain the capacity loss when compared with bare anode. Moreover, it is found that a thicker LiPON layer on anode would provide better capacity retention during storage aging. Meanwhile, the electrochemical impedance spectroscopy is recorded during aging and its equivalent circuit simulation is proposed. Also, the anode surface morphology with and without a LiPON layer is observed before and after aging. Based on these investigations and analysis, we conclude that the LiPON layer on the top of the anode would act as a protective layer and improve the capacity retention during storage aging at elevated temperature. 相似文献
19.
Bo Bao Peng Huang Bin Fu Puji Shi Yi Long Yongqin Chang Farong Wan 《Journal of magnetism and magnetic materials》2009,321(7):786-789
The magnetic properties and magnetocaloric effects (MCEs) in La0.8R0.2(Fe0.919Co0.081)11.7Al1.3 (R=Pr, Nd) compounds have been investigated. When Pr and Nd substitute for La, the Curie temperature of compounds decreases. The values of the MCEs are enhanced significantly by a partial substitution of Nd for La. Under the field change of 2 and 5 T, the maximum magnetic entropy changes for La0.8Nd0.2(Fe0.919Co0.081)11.7Al1.3 compound are −4.56 and −9.46 J/Kg K, respectively. It can be exploited for room temperature magnetic refrigeration material. 相似文献
20.
Three Al doped lithium nickel cobalt oxide (LiNi0.4Co0.4−xAl0.2+xO2) cathode materials for lithium ion batteries were synthesized by solid state reaction method at a temperature of 800 °C for
18 hours. The samples were crystalline as revealed by powder X-Ray diffraction (XRD). The ratios of the elements were determined
by Energy Dispersive Analysis of X-rays (EDAX). The electrochemical properties obtained by charge/discharge cycling showed
that the average discharge capacity for LiNi0.4Co0.4Al0.2O2 was 117 mAh/g. A good capacity retention was also shown by the material upon cycling.
Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 –
8, 2005. 相似文献