In this paper, with the goal of developing a high-performance silicon-based negative electrode through a reasonable green design using simple magnesium thermal reduction and pickling combined methods. Specifically, we utilize inexpensive photovoltaic waste silicon mud as the silicon source to synthesize porous silicon. Subsequently, we utilized self-produced porous silicon as the raw material and graphene as the coating material to fabricate a graphene-coated porous silicon-based negative electrode material with excellent cycling stability. We employ the PW91 method, which is based on density functional theory (DFT) using the generalized gradient approximation (GGA), to compute the first principles of both silicon-based materials and graphene-coated silicon/graphene composites. The study revealed that the P-Si@RGO composite exhibited excellent electrochemical properties. When adding 150 mL of graphene oxide with a concentration of 0.2 mg/mL. Even after the 100th cycle at a current density of 100 mA center dot g- 1, the specific discharge capacity of the P-Si@RGO electrode remains high at 1167.6 mAh center dot g- 1. At the same time, the results of DFT calculations also show that graphene can improve the conductivity of silicon materials. In summary, the experimental results are consistent with the results of the firstprincipal calculation, indicating that the computer simulation can predict the accuracy of the experiment, verify the empirical conclusions, and indicate the direction for designing the experimental scheme.

Ce-doped V2O5 thin films on FTO conductive glass substrates were prepared by electrodeposition-assisted sol-gel method. The influences of Ce doping on the phase, surface morphology and optical properties of V2O5 thin films deposited on FTO substrates were examined. The results revealed that the films have good crystallinity and high purity. Ce doping is slightly helpful to the increase of grain size of the films. With 1.0 at.

With the flourishing development of the photovoltaic industry, the waste of silicon slime generated by photovoltaic cutting has been a serious environmental problem, along with silicon resource waste. In this paper, the waste silicon slime produced by the photovoltaic industry was used as raw materials. Porous silicon particles were synthesized with the magnesium thermal reduction method, combined with hydrofluoric acid etching. The porous silicon can be applied to be the anode material of lithium-ion batteries. The synergistic effect of magnesium thermal reduction and acid etching on the preparation of porous silicon materials was studied. A lower heating rate of 5 °C/min will result in less heat accumulation, which can avoid the formation of large-sized Si/MgO composite particles and obtain a well-dispersed morphology. After a current density of 100 mA·g−1, the reversible capacity of porous silicon anode is 751.1 mAh/g after 50 cycles. Compared with commercial nano silicon, its cycle stability and cycle performance have been improved, which provides a new approach for green reutilization of waste silicon slime in the photovoltaic industry.

We present a simple method for producing SiO2-modified LiNi0.5Mn1.5O4 (LNMO) cathode materials. Manganese carbonate was directly mixed with nickel nitrate and lithium hydroxide, and a spherical structure LNMO cathode material was prepared by two-step calcination, then ethyl orthosilicate and LNMO powder were simply mixed in solid and liquid phases to prepare SiO2-coated LNMO material. The effect of SiO2 coating on the structure of LNMO was studied by diffraction of X-rays, scanning electron microscope (SEM), transmission electron microscope (TEM), and thermogravimetric analysis and differential scanning calorimetry. An amorphous SiO2 coating layer developed on the surface of the LNMO particles in the modification and this could alleviate the strike of hydrogen fluoride (HF) caused by electrolyte decomposition as well as the development of a solid electrolyte interphase. The electrochemical performance of the coated material was as follows: when the amount of SiO2 was 0 wt%, 1 wt%, 2 wt%, and 3 wt%, the initial discharge capacity of the sample was 98.2, 84.1, 101.3, and 89.8mAh/g, respectively. After 50 charge-discharge cycles, the capacity retention rates are 92.7%, 66.8%, 97.9%, and 93.8%, respectively. The cyclic stability of the samples can be significantly improved when the SiO2 coating amount is 2 wt% and 3 wt%, indicating that SiO2 coating can not only improve the discharge-specific capacity of the material but also improve its cyclic stability.

The nano VO2 powders were prepared by hydrothermal synthesis. The effects of Gd and Nd element doping on the structure and phase transition temperature of VO2 were studied. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) results showed that Gd element and Nd element will affect the structure of VO2. Gd3+ and Nd3+ can occupy partial position of V4+ lattice and form solid solution, increasing the lattice parameters of VO2. Both the doped and un-doped VO2 powders exhibit a monoclinic structure at room temperature. Due to the lattice deformation caused by Gd or Nd doping, the aggregation of particles is prevented, and the grain is refined obviously. Differential scanning calorimetry curves showed that both Gd doping and Nd doping can reduce the phase transition temperature of VO2(M). When the Gd doping concentration is 6 at%, the phase transition temperature can be reduced from 71.7°C to 60.3°C, and the infrared transmittance before and after the phase transition also changes significantly, reaching more than 40%. Nd doping is similar, and the phase transition temperature decreased to 55.6°C with the addition of 9 at% Nd.

The LiNi0.5Mn1.5O4 high voltage cathode for lithium ion batteries is prepared via simple coprecipitation method. The effect of the precipitation temperature, pH, and calcination temperature on the phase transformation, microstructure and electrochemical performance was investigated. On this basis, a comparative study on the morphology and electrochemical properties of the prepared and commercial LiNi0.5Mn1.5O4 cathodes was also conducted. The results indicate that the high-purity precursor was obtained with preparation pH and temperature is 11.5 and 50 °C, and then was mixed and ground with LiOH thoroughly, and then the mixture was calcined at 800 °C for 15 hours to obtain LiNi0.5Mn1.5O4 material, which demonstrated superior performance. Both the commercial and selfmade lithium nickel manganate cathode materials present typical spinel structure. Obvious particle agglomeration for poor dispersion could be observed in the commercial lithium nickel-manganate cathode material. The particles are dispersed uniformly, but some large-sized particles appeared in prepared cathode material. The initial discharge capacity is about 128.2 mAh/g at a rate of 1 C. After 100 cycles, the capacity retention of the prepared lithium nickel-manganate cathode material is 93.8%, while a lower capacity retention of 92.5% for the commercial cathode material.

采用水热合成结合高温热处理制备了VO2粉体,研究了Zr元素掺杂对VO2结构及相变性质的影响.结果表明:掺杂Zr元素会对VO2结构产生影响,Zr4+可以占据V4+晶格点阵位置,形成有限固溶体,从而增大VO2的晶胞参数,不同浓度Zr掺杂试样,仍呈VO2单斜相结构.由于掺杂导致的晶格变形,阻止了颗粒的聚集,因此Zr添加具有一定的细化晶粒作用.DSC曲线测试表明,Zr掺杂可以降低VO2(M)的相变温度,掺杂浓度为6％(原子百分比,下同)时,相变温度可由未掺杂的69.9℃降到61.1℃,Zr掺杂试样相变前后的红外透射率变化也较大,达到30％ 以上.

采用水热合成法制备了VO2粉体,研究了水热条件和Y、La、Ce等元素掺杂对VO2结构及相变温度的影响.结果表明:水热反应时间和温度对VO2晶粒生长影响显著,190℃保温72 h条件下制备的VO2粉体结晶度较好.稀土离子掺杂对VO2粉体成型和相变温度都有影响,其中Y掺杂能起到明显的细化晶粒作用,同时能使VO2相变温度由未掺杂时的68.3℃降到61.6℃;La和Ce的掺杂效果相近,都会对VO2主体结构产生一定破坏,虽然能起到一定降低相变温度的作用,但相转变效果较差.

NiFe2O4/nano-TiN ceramics were synthesized by a two-step cold-pressing sintering process. Sintering behavior, fracture morphology, mechanical performance and high-temperature conductivity were investigated. The results indicated that besides NiO and NiFe2O4, new Ni3TiO5 and metallic phases (iron and nickel) formed in the sintered samples. TiN accelerated the grain growth along with considerable quantity of micro-pores in the sintered samples. Compared to the un-doped samples, the temperature for the onset of sintering of the NiO-Fe2O3-2.0 wt.% TiN system decreased from 1093 to 985  °C. TiN addition changed the sintering mechanism of the NiO-Fe2O3 from grain boundary diffusion to volume diffusion. TiN additions reduce the apparent sintering activation energy and porosities and improve the density, bending strength, and pyroconductivity. Three-dimensional fracture morphology of the composite ceramics synthesized under argon atmosphere, exhibits self-similarity characteristics and the fractal dimension for NiFe2O4-1.0 wt.% TiN ceramics is 2.0813.

The VO2 powders were prepared by hydrothermal synthesis. The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied. The XRD, SEM and TEM results show that the heat treatment temperature has a significant effect on the crystal transformation of VO2 precursor. Increasing temperature is conducive to the transformation of precursor VO2(B) to ultrafine VO2(M). The Y-doping affects the structure of VO2. Y3+ can occupy the lattice position of V4+ to form YVO4 solid solution, which can increase the cell parameters of VO2. Due to the lattice deformation caused by Y-doping, the aggregation of particles is prevented, and the grain is refined obviously. DSC curves show that Y-doping can reduce the phase transition temperature of VO2(M). After adding 9 at.% Y, the phase transition temperature can be reduced from 68.3 to 61.3 °C.

NiFe2O4/nano-TiN ceramics were fabricated by a two-step cold-pressing sintering process. Effect of sintering atmosphere (air, nitrogen, argon) on the synthesis process of NiFe2O4/nano-TiN ceramics was investigated. The DSC-TG and XRD analysis results indicated that besides principal phases of NiO and NiFe2O4, new-phase Ni3TiO5 formed in the sintered ceramics under the three sintering atmospheres, and metallic phase including iron and nickel appeared in the sintered samples with inert gas (nitrogen, argon) sintering condition. Microstructure analysis results showed that considerable quantity of micropores appeared in the ceramic samples sintered under inert gases (argon, nitrogen), but lower porosity (3.0, 3.6%) and higher densities (4.78 g/cm3, 4.51 g/cm3) can be obtained, comparing to the both values (14.4%, 4.17 g/cm3) for the ceramic samples sintered under air atmosphere. Besides, the average bending strength and elastic modulus of the samples sintered under argon is 113.75 MPa and 7.13GPa, which is higher than that of 75.12 MPa, 5.42GPa and 91.96 MPa, 6.26GPa for the samples synthesized under air and nitrogen, separately. When changing sintering atmosphere from air to inert gases (argon, nitrogen), the fracture model of the 4 wt.%nano-TiN/NiFe2O4 ceramics synthesized at 1400 °C for 4 h transformed from intergranular fracture to intergranular-transgranular fracture.

利用高温真空热膨胀仪,采用恒升温速率法研究了升温速率和纳米TiN添加量对NiFe2 O4陶瓷基惰性阳极材料初期烧结行为的影响.结果表明,较低的升温速率可以促进烧结的致密化;纳米TiN可以降低Fe2O3-NiO体系的烧结颈温度,加快体系的致密化过程,TiN添加量为1％时,试样的线收缩率最大;TiN可以使得Fe2 O3-NiO体系的初期烧结机制由晶界扩散转变为体积扩散,同时也可以降低体系的烧结活化能,在TiN的添加量为1％时,体系的烧结活化能从未添加时的446.3 kJ/mol降低到了217.4 kJ/mol.

A two-step powder compaction and sintering process was employed to fabricate TiO2-doped NiFe2O4 ceramic-based inert anodes. Grain growth during isothermal sintering was analyzed using Brook grain growth model. The bubble behavior of NiFe2O4 ceramic-based inert anodes was investigated in a twocompartment see-through quartz cell for aluminum electrolysis process. Anodic overvoltage and potential decay curves of the inert anodes were measured by using the steady state and current interruption technique. The results showed that the kinetic index of grain growth decreased with an increase in temperature. The average activation energy of grain growth for 1.0 wt.% TiO2-doped NiFe2O4 ceramic samples with a sintering temperature range from 1373 to 1673 K dropped from 675.30 to 183.47 kJ/mol. The diameter size of bubbles before releasing from the bottom surface of the anodes was reduced with increasing the current density, and the larger average releasing bubble size for carbon anode at the same current density could be obtained, which was compared to the NiFe2O4 inert anodes. Besides, the cell voltage of carbon anodes fluctuated much more violently under the same experimental conditions. After adding small amount of TiO2, a minor reduction in anodic overvoltage of NiFe2O4-based anodes can be observed.

The influence of heating rates and MnO2 additives on early-stage sintering behavior to synthesize NiFe2 O4 has been investigated.The results show that lower heating rates can produce more obvious shrinkage. Introduction of MnO2 can shift the onset of sintering toward lower temperatures.The early-stage sintering of NiO-Fe2 O3 system is mainly controlled by grain boundary diffusion.For MnO2-doped samples,the early-stage sintering mechanisms are controlled by volume diffusion.The apparent activation energy of these doped samples decreased obviously,and for the 1.0wt% MnO2-doped sample,apparent activation energy decreased from 813.9 to 441.9 kJ/mol.

V-Ti-Fe as hydrogen storage alloy was prepared by reducing metal oxides with a metallothermic reduction method. The deoxidation process of the V-Ti-Fe alloy was performed by electro-deoxidation and vacuum induction melting method, respectively. The results showed that the content of oxygen impurity can be controlled at about 0.2wt% after electrolyzing for 240min. Both the maximum values of hydrogen absorption capacity and the effective hydrogen desorption capacity are 2.65wt% and 1.01wt%, respectively. The deoxidization effect of vacuum induction melting process is more remarkable, with Ce as the reducing agent. It is found that Ce addition is beneficial for reducing the componential segregation, promoting the hydrogen absorption activation of V-Ti-Fe alloy. When m(Ce)/m( alloy) is up to 5%, the oxygen content has been reduced to 0.05wt% and the maximum hydrogen absorption capacity and the effective hydrogen desorption capacity are up to 3.36wt% and 1.85wt%, respectively.

NiFe2O4 ceramic based inert anodes were fabricated by a two-step cold-pressing sintering process. The bubble behavior of NiFe2O4 ceramic based inert anodes was investigated in a two-compartment see-through quartz cell. Anodic overvoltage and potential decay curves on the inert anodes were measured by using the steady state and current interruption technique. The results show that the electrolytic gas evolution for NiFe2O4 inert anodes, including bubble nucleation, growth, coalescence, growth again, migration and escaping, lasts for 79s and the escaping bubble size is about of Φ4mm×2mm. While gas evolution lasts for 102s of carbon anodes with larger releasing bubbles. When current densities are 0.6, 0.8, 1.0 and 1.2A/cm2, the anodic overvoltage of NiFe2O4 anodes are 0.189 V, 0.270 V, 0.309 V and 0.359 V, respectively. After adding small amount of MnO2, V2O5, and TiO2, a minor reduction in anodic overvoltage of NiFe2O4 anodes can be obtained.

TiO 2 ‐doped NiFe 2 O 4 samples were prepared via ball‐milling and two‐step sintering processes. Besides NiFe 2 O 4 phase, two new phases, NiTiO 3 and Fe 2 TiO 5 , formed in TiO 2 ‐doped samples. The temperature of sintering onset for 1.0 wt% TiO 2 ‐doped samples is 230°C lower than that of undoped samples. Early‐stage synthesis process of TiO 2 ‐doped NiFe 2 O 4 ceramics is controlled by grain boundary diffusion mechanism. Increasing TiO 2 content from 0 to 1.0 wt%, the apparent activation energy decreased from 813.919 KJ/mol to 639.361 KJ/mol. The values of relative density and bending strength reached their maximum value with 1.0 wt% TiO 2 . Saturation magnetization, residual magnetization ratio and coercivity decrease with increasing TiO 2 content.

Microstructure evolution and the changes in mechanical properties of HR3C steel during long-term aging at 650, 700 and 750 °C were investigated. The precipitated phases of the aging steel included M23C6 carbides, Z-phase and a trace amount of Nb(C,N). The M23C6 carbides were distributed mainly at the grain boundary, while Z-phase was mainly inside the grains. Amounts of both M23C6 carbides and Z-phase during the aging process increased with increasing aging period and temperature. Coarsening of M23C6 carbides was influenced significantly by aging time and temperature, while the size of the Z-phase was relatively less affected by the aging time and temperature, which had a steady strengthening effect. Coarsening of the M23C6 carbides was the main reason for the decline in high temperature yield strength during long-term aging at 750 °C. The M23C6 carbides were linked into a continuous chain along the grain boundary which accounted for the decrease of toughness during aging.

To investigate the effect of high temperature ageing on the microstructure and mechanical properties of S31042 steel, solid solution treatment at 700 °C was carried out for various time from 10 to 6000 h. Experimental results showed that the change of mechanical properties is closely related to the amount of precipitated phases. During ageing from 10 to 300 h, precipitation in the tested steel increases rapidly, and correspondingly, the high temperature yield strength and room temperature hardness of tested steel increase rapidly. Meanwhile, the thickness of the secondary phase on grain boundaries widens sharply and the room temperature Charpy impact absorb energy decreases. Ageing beyond 300 h, the precipitation in the steel increases gradually and the precipitates coarsen to a certain extent. The high temperature yield strength of the steel keeps stable, and the room temperature Charpy impact energy and hardness decrease slowly. Ageing beyond 3000 h, the mechanical properties of the steel tend to be stable. The main precipitates are M23C6, NbCrN and NbC in the tested steel.

The spray refining process was carried out to reduce the impurities of V-Ti-Fe master alloy.The influences of slag compositions and temperature on refining effect were investigated.The results showed that when the ratio of m（CaF2）/m（CaO） is 3.0,the slag amount is 35% of the alloy amount,the TiO2 amount is 10% of the slag amount and the refining temperature is 1 600 ℃,a good refining effect is obtained.The content of Al decreases to 2.61% from 7.11% after the refining process.However the content of Si just decreases to 0.97% from 1.25%,the change range is smaller.XRD and SEM results showed that the refining process can remove oxide inclusions effectively.In addition,the componential segregation of the alloy is reduced after the refining process.