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A simple method was developed to prepare the uniform hematite hollow submicro-spheres with controllable structure and different diameter based on monodisperse poly(styrene-co-acrylic acid) [P(St-co-AA)] particles. The structure and formation mechanism of the hollow spheres were investigated in detail. The control mechanism of shell thickness was also discussed. The results indicated that the shell thickness and coarseness of the synthesized core-shell hematite hollow spheres could be tuned simply by the surface carboxyl content of the P(St-co-AA) particles. This method provided a new approach for the structure control in the preparation of hollow spheres. A Brunauer-Emmett-Teller (BET) test shows that the prepared hollow spheres have large surface areas which were decreased along with the increase of the diameter. The magnetic properties of the as-obtained hematite hollow spheres were investigated. The result showed that the coercivity and saturated magnetization were increased along with the increase of the shell thickness, and the remanent magnetization was increased along with the decrease of the diameter. 相似文献
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制备了酞菁钴(CoPc)-Fe3O4纳米复合粒子,研究了其化学稳定性.结果表明.CoPc与Fe3O4纳米粒子通过一定程度的化学键作用形成了有效的复合.在Fe3O4纳米粒子表面形成了包覆层,有效地保护其不被空气氧化。其抗氧化能力与CoPc包裹层的数目有很强的依赖关系。 相似文献
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光学透明材料的现状和研究进展:Ⅱ:有机—无机纳米复合光学透?… 总被引:1,自引:0,他引:1
评述了有机-无机纳米复合光学透明材料的研究现状,重点分析了用溶胶-凝胶法、胶体化学法等有机-无机纳米复合技术在合成高性能光学透明材料时存在的问题及可能解决的途径,并指出研究和开发高性能、功能化的有机-无机纳米复合光学透明材料将成为该领域的重点和一次发展趋势,并将推大光学透明材料的应用领域。 相似文献
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Polyoxometalates (POMs) are useful catalysts in both redox and acid catalysis reactions since its catalytic features can be controlled at a molecular level. We investigated POM (POM = H3PW12O40) on tantalum pentoxide (Ta2O5) via hydrolysis of tantalum pentachloride (TaCl5) in the presence of POM using the sol-gel method for acid catalytic reaction. All obtained amorphous materials have been characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FT-IR) spectra, Raman scattering spectroscopy, 31P magic-angle spinning (MAS) NMR, field emission scanning electron microscopy (FESEM), and nitrogen adsorption/desorption analysis, in order to confirm the structure integrity of the Keggin unit in as-prepared composites and investigate the morphology and surface textural property of the composites. Catalytic activity of the catalysts has been evaluated for esterification of acetic acid with ethanol as a model reaction with different catalytic reaction parameters such as POM loading, reaction time, catalyst dose, molar ratio of the reactants, etc. The conversion of ethanol reached 87.4 % and the turnover frequency (TOF) was 2.9×103.Meanwhile, it is easy to separate and recover POM/Ta2O5 from the reaction system. 相似文献
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纳米铁/SiO2核壳复合粒子的制备与性能表征 总被引:5,自引:1,他引:5
利用硅烷偶联剂 APS和活性硅作表面活性剂 ,采用种子包埋法 ,制备了纳米铁 / Si O2 核壳复合粒子。用 TEM、TG- DTA、VSM对材料结构与性能进行表征。TG- DTA表明纳米铁表面没有吸附水和结晶水 ,而抗氧化能力提高。VSM研究发现包裹一层二氧化硅后 ,饱和磁化强度与剩磁对比纳米铁粉减小 ,而矫顽力增大 相似文献
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电磁屏蔽材料用银包玻璃微珠核-壳粒子的制备及其性能 总被引:3,自引:0,他引:3
采用自组装化学镀银技术制备了银包玻璃微珠核-壳粒子,并且运用X射线衍射仪、扫描电镜和电子能谱仪等对该核-壳粒子的物相和形貌等进行了表征.分析了该核-壳粒子的介电性能与结构的关系,并以此为屏蔽填料,研究了电磁屏蔽涂料的相关性能.结果表明,银粒子在玻璃微珠的表面包覆均匀且致密,该粒子的介电常数较包覆前大幅度提高.该电磁屏蔽涂料的导电性能随着填料的体积分数(下同)的增加而增加,达到25%时,其表面电阻率为0.050 7Ω/cm2.同时,在电磁波的频率范围为30~1 500MHz时,屏蔽效能达40~65 dB,并且该材料具有较好力学性能和耐环境性能. 相似文献
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