Submicrometer-sized hollow nickel spheres synthesized by autocatalytic reduction

A facile method to fabricate submicrometer-sized hollow nickel spheres by autocatalyzing the redox reaction around a sacrificial colloidal particle surface is presented in this paper. The size distribution of these spheres can be controlled by regulating the concentration of the alkali solution. The hollow nickel particles were characterized by field emission scanning electron microscopy, transmission electron microscopy and X-ray powder diffraction. The hollow spheres produced by this process may have potential applications in many fields, including chemistry, biotechnology and materials science.     

基于物-场模型的纳米空心镍球的制备方法研究

针对目前混镍粉电火花腐蚀制备纳米空心镍球,存在着蚀除电极金属液滴与工作液中的小气泡不能充分结合,形成中空结构的问题,采用创新设计方法及知识库进行解决.根据实际工况,构建问题物 场模型,在知识库中搜索多种场,获得相应的解决方案.运用模糊评价法对多种方案进行评价与排序,挑选出最优方案--采用超声波场代替原有的机械场,开发出超声波制备纳米空心镍球装置,较好地改善了原有系统制备空心镍球的质量和效率.     

硫掺杂TiO_2空心球制备及光催化性能研究

以聚苯乙烯-丙烯酸羟乙酯共聚(P(StHEA))微球为模板、钛酸四丁酯和硫脲为主要原料,制备了硫掺杂二氧化钛(S-TiO2)空心球,采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和X光电子能谱(XPS)表征产物的形貌、晶型以及硫元素的掺杂状态,并以甲醛溶液模拟废水,研究了S-TiO2空心球的紫外光催化性能。结果表明,煅烧去除了P(St-HEA)微球模板,成功得到TiO2空心球,硫元素掺杂对TiO2空心球的粒径和形貌影响不大。STiO2空心球锐钛矿型晶粒的尺寸缩小,晶型由纯的锐钛矿型转化为锐钛矿/金红石型混合晶型。硫脲引入的硫离子,以S4+状态取代TiO2晶粒中的Ti4+离子,形成Ti1-xSxO2固溶体。S-TiO2空心球光催化性能优于TiO2空心球,且空心球的光催化性能优于粉体P25。STiO2空心球在紫外光下照射2 h,降解甲醛的催化效率为60%。     

Fabrication of hollow silver spheres by MPTMS-functionalized hollow silica spheres as templates

In this study, we provide a strategy to prepare the hollow silver spheres by accumulating the silver nanoparticles on the surface of 3-mercaptopropyltrimethoxysilane (MPTMS)-functionalized silica as templates, which was accomplished by the chemisorption between silver nanoparticles and thiol groups. Then, the resulting hollow silver spheres were obtained through the chemical wet etching process with 10 M HF solution. In conventional method, the fabrication of hollow silver spheres from core-shell spheres was not easy due to the difficulties in retaining the shell structures during core removal. The method in this paper could overcome this limitation. The major focus of study is on understanding the mechanism of formation of the hollow silver spheres through the self-assembly behavior by chemisorption between silver nanoparticles and thiol groups. The silver-coated silica and hollow silver spheres were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), and X-ray photoelectron spectroscopy (XPS).     

Synthesis and optical properties of ZnS hollow spheres from single source precursor

A facile one-pot synthesis of ZnS hollow spheres has been carried out via a chemical transformation induced inside-out Ostwald ripening process from a single source precursor. The size and shell thickness of the ZnS hollow spheres can be controlled by adjusting the reaction temperature and reaction time, respectively. Photoluminescence spectra show a dominant emission peak at 470 nm accompanied by several weaker peaks. UV-vis measurement reveals that the obtained ZnS hollow spheres exhibit “hollow effect”. The formation process of ZnS hollow spheres has been discussed.     

Preparation and optical property of anatase hollow microsphere with mesoporosity

Anatase hollow sphere with mesoporosity was prepared by sol pyrogenation used TiCl₄ as precursor only. The samples were characterized by X-ray diffraction and scan electron microscopy, their specific surface area was measured by N₂ adsorption. The results show that the sample calcined at 500 °C for 2 h is phase pure anatase, the morphology of the particle of the sample is hollow sphere, and the wall of the hollow sphere is constituted of anatase nanoparticle and mesoporosity. The crystallinity, the crystal size, the pore width, the specific surface area and the crystal phase of the sample are changing along with the calcined temperature. The optical property was measured by ultraviolet radiation vis absorption spectra of the suspension of the samples. The results show that the optical property of the sample is better than that of nanoanatase particle, and the optical property of hollow sphere titania with mesoporosity is related to its crystal phase, specific surface area, crystal size, porosity size and crystallinity.     

Tunable diode laser absorption spectroscopy in coiled hollow optical waveguides

We demonstrate tunable diode laser absorption spectroscopy of CO2 and NH3 near 1.5 microm using a distributed feedback diode laser in conjunction with hollow optical waveguides as long-path sample cells. The waveguides are coiled to reduce the physical extent of the system. The small volume of the waveguide provides rapid instrument response to changes in gas concentration. To reduce the pressure drop associated with long lengths and high flow rates, we perforate the waveguides in a novel geometry providing parallel pneumatic paths while maintaining optical path length. A minimum detectable absorbance of 3.5 x 10(-5) in a 3-m section of waveguide is demonstrated.     

Sol-gel synthesis of titania hollow spheres

TiO₂ hollow spheres are prepared by a convenient sol-gel method at room temperature. The products were characterized by XRD, FESEM, TEM and FT-IR. It was found that these spheres are hollow inside with outer diameters of 200-500 nm. The average mesoporous diameter is about 9.8 nm. And the BET surface area and specific pore volume are about 161.9 m²/g and 0.441 cm³/g, respectively.     

电化学研磨法制备超细镍粉

以锂离子电池为微反应器,电化学还原NiO制备了超细镍粉。X射线衍射结果表明所得粉末为纯相Ni,晶粒尺寸约5nm。激光粒度分布测试结果表明Ni粒度分布较窄,中位径集中在200～600nm。透射电镜照片显示颗粒粒径在80～200nm之间;放电电流密度的增加和放电温度的提高都使产物粒径有变大的趋势;在分散过程中加入不同的表面活性剂,可以提高产物Ni的分散性能。     

氧化锌空心球的制备及光致发光特征

采用水热和硬模板辅助技术,成功制备得到ZnO空心球结构.以葡萄糖和锌盐为原料,首先通过催化葡萄糖聚合-原位离子吸附一步进行(一步法)或葡萄糖聚合成球-离子吸附分步进行(二步法)制备锌/炭复合微球,然后经空气低温氧化制得ZnO空心球.用XRD、SEM、TEM研究产物的组成和结构及形貌,用光致发光光谱(PL)测试产物的室温光致发光性能.研究发现,两种方法得到的空心球壳均属多孔结构,由ZnO纳米粒子构成;与聚合-吸附分步法相比,聚合-原位离子吸附一步法更加简单快捷;制得的ZnO空心球结构材料具有良好的近紫外发光性能.对ZnO空心球结构的形成过程和可能的机制进行了分析和讨论.     

TiO2空心微球制备及研究进展

氧化钛空心球特殊的结构及在光电、催化、气敏等方面的优异性能及在太阳能电池、光催化、环境净化、气体敏感器等领域的潜在应用价值,吸引了越来越多的科学工作者的关注,并取得了一定的成果.对氧化钛空心球的制备及应用现状进行了研究,并展望了其发展趋势.     

Templating synthesis of waxberried hematite hollow spheres

Novel hematite (α-Fe₂O₃) hollow spheres were prepared through a surfactant-assisted solvothermal process. The XRD, SEM and TEM characterization data confirm that the formation of α-Fe₂O₃ hollow spheres exhibits waxberry-like architectures with spindle nanoparticles, the length in the range of 150-400 nm, as building block. Their tips of these nanoparticles were concentrated on a center. The sizes of α-Fe₂O₃ waxberry are less than 3 µm. They possess good photocatalytic properties when used for the degradation of salicylic acid in water. The formation mechanism of α-Fe₂O₃ waxberry is also discussed.     

Preparation and characterization of CdS hollow spheres

CdS hollow spherical particles with average diameter of 800 and 850 nm have been prepared using core/shell fabrication method with poly-(styrene-acrylic acid) (PSA) latex particles as template. TEM images show that smoothly coated core/shell composite particles have been fabricated by multicycles of coating in optimum concentration of reactants. CdS hollow spheres were obtained after removing the template by dissolving the polymer in the organic solvent, and the wall thickness is about 40-100 nm.     

金属空心微球的制备及应用现状

金属空心微球不仅具有一般金属空心球的结构和性能等特点，而且还具有小尺寸的独特优势，可望在微电子、微系统和生命科学等诸多前沿领域发挥重大的作用。介绍了金属空心微球的制备和应用现状，并对存在的问题进行了的讨论。     

The sintering of nickel/aluminium spheres to nickel plates

Spheres of nickel, and of nickel containing 0.5,1.0, 2.0, and 10.0 wt % aluminium, all of approximately 100m diameter, were sintered under vacuum to nickel plates for various times within the temperature range 1000 to 1300° C. Neck growth was determined as a function of time. Values for the exponent of time in the neck growth equation,x/a = At ⁿ of 0.19, 0.18, 0.15, and 0.16 were found for the above compositions, respectively. An activation energy of 33 kcal/mole was found for sintering nickel spheres to nickel plates. An activation energy of 69 kcal/mole was found for sintering Ni/1.0% Al spheres to nickel plates.Assuming a surface-diffusion mechanism of material transport, as suggested by Nichols and Mullins, the difference in activation energies is explained on the basis of a difference in surface energy, as reflected in the ease with which vacancies are formed at the surface. Similar reasoning is employed to explain the difference in activation energies found between sintering nickel spheres to nickel plates under vacuum in this research, and sintering nickel wire compacts under a hydrogen atmosphere in work reported by Pranatis and Siegle.From the thesis submitted by A. G. Elliot in partial fulfilment of the requirements of the degree of Master of Science in Materials Science.     

A room-temperature synthesis of titanium nitride hollow spheres

Titanium nitride hollow spheres were synthesized by the reaction of TiCl4 and NaNH2 at room temperature. X-ray powder diffraction (XRD) pattern could be indexed as cubic TiN with the lattice constants of a = 4.236 A. Transmission electron microscopy (TEM) images showed hollow spheres with diameter about 200 nm. A possible formation mechanism of TiN hollow spheres was discussed.     

Synthesis of red-luminescent Eu-doped lanthanides compounds hollow spheres

Eu³⁺-doped Y₂O₃, YOF, La₂O₃, LaOF hollow spheres have been synthesized by a facile template route. Eu³⁺ were doped into the various host materials to make the hollow sphere red-luminescent. Difference in fluorescence spectra recorded on the hollow spheres were compared in detail and attributed to the different crystal symmetry of host materials. These phosphors might find applications in the fields such as light phosphor powders, advanced flat panel display, or biological labeling.     

氧化硅空心微球的制备及表面形貌的调控

采用改进的St(o)ber溶胶凝胶法制备聚苯乙烯(PS)/氧化硅(Silica)复合微球,研究了添加油酸对复合微球形貌的影响.微球在经过500℃高温煅烧后,得到氧化硅空心微球.应用HPPS、Zeta电位分析、TEM、SEM、氮气吸附等手段对空心微球进行研究,证实了在包裹过程中油酸与氨水作用生成的油酸铵吸附在聚苯乙烯微球表面,增加模板微球表面电势从而有利于氧化硅粒子在其表面成核生长.此外油酸与硅羟基之间形成氢键增加氧化硅的生长点,增加了氧化硅壳层的密实程度.