LiMn_2O_4与Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3/Li_7La_3Zr_2O_(12)的复合正极材料制备及性能研究

正极材料在锂离子电池服役过程中的电化学稳定性是目前研究的热点之一,研究锰酸锂复合正极材料,探索改善正极材料电化学稳定性的工艺与方法。采用高温固相法制备LiMn_2O_4和NISICON结构的Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3、石榴石结构的Li_7La_3Zr_2O_(12),将LiMn_2O_4和Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3/Li_7La_3Zr_2O_(12)以9∶1的比例混合制备复合正极材料。利用X射线衍射仪分析其物理性能,组装成扣式电池,通过恒流充放电测试、循环伏安测试、阻抗测试等进行电化学性能分析。结果表明,LiMn_2O_4/Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3复合正极材料和LiMn_2O_4/Li_7La_3Zr_2O_(12)复合正极材料依然为尖晶石结构,材料结晶度良好。其中,LiMn_2O_4/Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3复合正极材料衍射峰相对尖锐,峰强较大。充放电测试表明,LiMn_2O_4/Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3复合正极材料的放电比容量比LiMn_2O_4/Li_7La_3Zr_2O_(12)复合正极材料的放电比容量高,化学反应的可逆性更佳。所以,LiMn_2O_4/Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3复合正极材料的性能优于LiMn_2O_4/Li_7La_3Zr_2O_(12)复合正极材料。     

可见光响应TiO_2/Bi_4Ti_3O_(12)复合粉的制备及表征

以熔盐法制备的微米级片状TiO_2/Bi_4Ti_3O_(12)为基体,采用Ti(SO4)2水解结合后续热处理的方法制备了TiO2/TiO_2/Bi_4Ti_3O_(12)复合粉,研究了原料配比对复合粉晶体结构、形貌以及光催化降解脱色效果的影响。结果表明:该复合粉的形貌为微米级片状TiO_2/Bi_4Ti_3O_(12)表面分布着纳米级的TiO_2颗粒;当原料中铋、钛物质的量比低于1∶6时,复合粉对亚甲基蓝具有良好的吸附脱色效果,钛含量过多时会导致水解产物的团聚,降低复合粉的比表面积,使其脱色效果变差;当铋、钛物质的量比为1∶4时,复合粉的比表面积为13.444 m~2·g~(-1),可见光光照4h以内,对亚甲基蓝的脱色率达到85%,其光催化降解脱色速率高于TiO_2/Bi_4Ti_3O_(12)的。     

国产袖珍DT-8888型4(1/2)位多功能数字万用表的工作原理与设计

本文介绍了国产袖珍式DT-8888型4(1/2)位多功能数字万用表的主要功能与技术指标,并结合主体电路工作原理的分析,讨论了具体电路的设计。     

STEM study of Li4Ti5O12 anode material modified with Ag nanoparticles

Comprehensive scanning transmission electron microscopy (STEM) analysis of Li₄Ti₅O₁₂ (LTO) powder modified by deposited Ag nanoparticles was performed. Nanocomposite powders with Ag content of 1 wt.%, 4 wt.%, 10 wt.% were fabricated in a chemical process from suspensions of Ag and LTO. Apart from the STEM results, the presence of pure silver on the surface of the ceramic powder was confirmed by XRD and XPS analyses. The silver particles deposited on the LTO particles were characterized using the EDS mapping technique. The quantified results of the EDS mapping showed a relatively homogenous distribution of silver nanoparticles on the powder surface for every metal content. The mean diameter of the nanoparticles deposited on the LTO powder was about 4 nm in all cases. An increase in the Ag content during chemical surface modification did not cause changes in the microstructure. Focusing on an analysis of the metallic nanoparticles on the ceramic powder, electron tomography was used as an investigative technique. A very precise analysis of three‐dimensional nanostructures is desirable for a comprehensive analysis of complex materials. The quantified analysis of the Ag nanoparticles visualized using electron tomography confirmed the results of the size measurements taken from the two‐dimensional EDS maps.     

Growth and characterization of V2O5 thin film on conductive electrode

Vanadium pentoxide V₂O₅ thin films were grown at room temperature on ITO coated glass substrates by electrochemical deposition. The resulting films were annealed at 300, 400 and 500°C for 1 h in ambient environment. The effect of heat treatment on the films properties such as surface morphology, crystal structure, optical absorption and photoluminescence were investigated. The x‐ray diffraction study showed that the films are well crystallized with temperatures. Strong reflection from plane (400) indicated the film's preferred growth orientation. The V₂O₅ films are found to be highly transparent across the visible spectrum and the measured photoluminescence quenching suggested the film's potential application in OPV device fabrication.     

Fabrication of resistance type humidity sensor based on CaCu3Ti4O12 thick film

A resistance type humidity sensor has been fabricated from an assembly of CaCu₃Ti₄O₁₂ thick film, Ag interdigitated electrodes, and an Al₂O₃ ceramic substrate. The humidity sensing properties were measured using the direct current (DC) analysis method. The results show that the electrical properties of the CaCu₃Ti₄O₁₂ thick film are dependent on humidity and applied voltage. At low humidity, the film exhibited low conductivity and behaved as an insulator. However, at high humidity, the conductivity of the film increased due to the enhancement of ion conduction. These outcomes indicate that the measured resistance is highly dependent on the applied bias voltage within the whole humidity range i.e. 20–90% relative humidity (RH) at ambient temperature. The response and recovery times as well as sensitivity were determined to be around 2.8 min, 25 min, and 98.2%, respectively. Therefore, it is concluded that CaCu₃Ti₄O₁₂ thick film has good humidity sensing properties and has high potential in the application for fabrication of high-performance humidity sensors.     

基于离子束溅射Ta2O5薄膜的紫外吸收膜技术

为获得高性能紫外激光薄膜元件,急需研制紫外高反射吸收薄膜,实现吸收损耗的精确测量。本文采用离子束溅射技术,通过调控氧气流量实现了具有不同吸收的Ta_2O_5薄膜的制备。以Ta_2O_5薄膜作为高折射率材料,设计了355nm的紫外高反射吸收薄膜。采用离子束溅射沉积技术,在熔融石英基底上制备了355nm的吸收薄膜,对于A=5%的紫外吸收光谱,在355nm的透射率、反射率和吸收率分别为0.1%,95.0%和4.9%;对于A=12%的紫外吸收光谱,在355nm的透射率、反射率和吸收率分别为0.1%,87.4%和12.5%。实验结果表明,采用离子束溅射沉积技术,可以实现不同吸收率的355nm高反射吸收薄膜的制备,对于基于光热偏转测量技术的紫外光学薄膜弱吸收测量仪的定标具有重要的意义。     

五自由度码垛机器人控制系统设计

本文首先针对五自由度机器人的工作特点和工作环境,对机器人的操作系统和控制器进行选择,确定了控制方式。接着详细介绍了整个控制系统的组成部分及相应的功能,设计了几种工作模式,并针对各种工作模式编辑了控制软件,最后针对工作过程中可能出现的一些故障给出了相应的解决方案。     

基于面向对象的球形储罐CAD系统的设计与实现

介绍了基于面向对象的球形储罐 CAD系统——STCAD1.0的设计方案和软件实现,该系统采用 VisualC 6.0开发,可在 Win9X 及WinNT平台下运行,实现了球形储罐的结构设计、强度计算及设计说明书与设计图的自动生成。     

基于面积对象的球形储罐CAD系统的设计与实现

介绍了基于面向对象的球形储罐CAD系统－－STCAD1．0的设计方案和软件实现，该系统采用VisualC 6．0开发，可在Win9X及WinNT平台下运行，实现了球形储罐的结构设计、强度计算及设计说明书与设计图的自动生成。     

基于面向对象的搅拌反应釜CAD系统的分析和设计

介绍了基于面向对象的搅拌反应釜CAD系统的开发过程，实现了搅拌反应釜的结构设计、强度计算及设计说明书与设计图的自动生成。     

面向设计制造的船用柴油机零件全三维数字化定义研究

基于全三维的数字化定义是产品设计制造一体化的发展趋势,针对船用柴油机零件结构复杂等特点,实施全三维数字化定义方法.采用基于特征的三维标注技术和数据管理技术,同时将设计信息、加工制造信息和工艺信息依据制造工序进行合理组织与管理,置于三维软件平台中.在制造时,直接在三维模型上识别加工制造信息和工艺信息,摆脱二维图纸束缚.实验表明,采取该方法可以实现基于全三维模型的统一数据源,满足设计制造对全三维数字化模型的要求.     

过量Bi2O3对熔盐法制备钛酸铋的影响

采用NaCl-KCl熔盐法制备了各向异性的片状Bi4Ti3O12粉体,研究了过多Bi2O3对粉体尺寸、形貌以及陶瓷的显微组织和介电性能的影响。结果表明：Bi2O3过量对Bi4Ti3O12的相结构无影响,随过量Bi2O3的增加,Bi4Ti3O12粉体的尺寸及各向异性的程度均有所增大;烧结后的Bi4Ti3O12陶瓷晶粒呈片状,且随Bi2O3含量的增加,钛酸铋陶瓷密度和介电常数先增加后降低,绝缘电阻率随之逐渐减小,介电损耗显著增大。