在乙醇介质中制备SiO2光子晶体及其表征

以乙醇为介质,用二氧化硅球沉降法制备有序性较好的人工欧泊(Opal),并对二氧化硅球排布进行了显微形貌及透射谱表征.结果显示二氧化硅微球有序堆积,其结构为类面心立方晶型,与目前的理论研究结果符合得很好.     

蛋白石薄膜及其异质结构的可控制备

利用毛细管辅助沉积方法制备了厚度及膜内裂缝的形状、分布可控的三维蛋白石薄膜。讨论了所得薄膜光学性质以及膜的形态特性与薄膜厚度之间的关系。用同样的方法制备了由不同粒径的球体基元晶体带构成的横向交替异质结构。     

反蛋白石结构硫化锑光子晶体的制备

用改进St ber法制备出单分散的SiO2胶球.通过离心沉降法将SiO2胶球有序排列,得到蛋白石结构的SiO2光子晶体,该方法可制备出较大尺寸的蛋白石结构光子晶体.以得到的SiO2光子晶体为模板,通过化学反应向模板间隙填入Sb2S3后再经氢氟酸腐蚀去除二氧化硅胶晶模板,制备出反蛋白石结构硫化锑光子晶体.     

Treating temperature effect on bandgap in polymer opal photonic crystals

The optical reflective spectra and microstruc- tures of polystyrene opal photonic crystals treated with dif- ferent temperatures have been investigated. With tempera- ture increasing, the polystyrene spheres in opal structure transform to dodecahedrons, and the peak of reflective spec- trum moves to shorter wavelength. The experiment result testifies the effect of the effective refractive index and the filling ratio to the bandgap position, and it corresponds to the theoretical simulative result.     

Resolving the 'opal paradox' in the Southern Ocean

In the Southern Ocean, high accumulation rates of opal--which forms by precipitation from silica-bearing solutions--have been found in the sediment in spite of low production rates of biogenic silica and carbon in the overlying surface waters. This so-called 'opal paradox' is generally attributed to a higher efficiency of opal preservation in the Southern Ocean than elsewhere. Here we report biogenic silica production rates, opal rain rates in the water column and opal sediment burial rates for the Indian Ocean sector of the Southern Ocean, which show that the assumed opal paradox is a result of underestimated opal production rates and overestimated opal accumulation rates. Our data thus demonstrate that the overall preservation efficiency of biogenic opal in this region is substantially lower than previously thought, and that it lies within a factor of two of the global mean. The comparison of our revised opal preservation efficiencies for the Southern Ocean with existing values from the equatorial Pacific Ocean and the North Atlantic Ocean shows that spatial differences in preservation efficiencies are not the primary reason for the differences in sedimentary opal accumulation. The reconciliation of surface production rates and sedimentary accumulation rates may enable the use of biogenic opal in the reconstruction of palaeo-productivity when the factors that affect the Si/C ratio are better understood.     

Synthesis of 3D ordered porous polystyrene using silica template

A rigid colloidal silica template was formed by self-assembly of the monodispersed silica spheres prepared according to Stober method. The silica template is highly ordered, which was verified by bright color effect due to Bragg diffraction and the results of SEM. The free radical polymerization of styrene was allowed within the interstices of the rigid template to result in the formation of the three-dimensional periodic silica/polystyrene nano-composites. The titled porous polystyrene was prepared by chemical decomposition of the template with concentrated aqueous hydrofluoric acid. Scanning electron microscopy characterization showed that the macroporous polystyrene has ordered arrays of the uniform pores replicated from the template. Moreover, it was found that the morphology of the as-synthesized macroporous polystyrene was greatly affected by the connectivity of the silica spheres treated under different conditions.     

Synthesis and Characterization of Ordered Meso-Macro-Porous Silica Membranes on a Porous Alumina Support

Macroporous silica materials with ordered three-dimensional pore structure can be easily prepared by the template-directed sol-gel process. However, it is still a challenge to prepare them in membrane form on a porous support, which limits their applications. In this work, we have demonstrated the feasibility of obtaining a three-dimensional ordered macroporous silica membrane on macroporous alumina support using poly-methyl methacrylate (PMMA) spheres as the template. PMMA spheres were packed on the top of an Anopore-alumina support by filtration of a PMMA aqueous suspension. Silica sol obtained by an acid-catalyzed sol-gel process was infiltrated into the voids among the spheres. Drying induced stress caused the membrane to crack or peel off from the top of the support. This can be minimized by annealing the PMMA template layer before the introduction of silica sol which increases the mechanical strength of the template. Calcination or solvent extraction to remove the template produced a highly ordered three-dimensional macroporous silica membrane with spherical pores connected by windows in the mesoporous range. The results show that the PMMA-templated infiltration method is effective in preparing three-dimensional ordered macroporous silica membranes on a porous support.     

Size tuning and oxygen plasma induced pore formation on silica nanoparticles

Silica nanoparticles have been prepared from tetraethylorthosilicate dissolved in ethanol followed by base-catalyzed condensation.Earlier works reported that at least four parameters,namely concentrati...     

Large-scale synthesis of a silicon photonic crystal with a complete three-dimensional bandgap near 1.5 micrometres

Photonic technology, using light instead of electrons as the information carrier, is increasingly replacing electronics in communication and information management systems. Microscopic light manipulation, for this purpose, is achievable through photonic bandgap materials, a special class of photonic crystals in which three-dimensional, periodic dielectric constant variations controllably prohibit electromagnetic propagation throughout a specified frequency band. This can result in the localization of photons, thus providing a mechanism for controlling and inhibiting spontaneous light emission that can be exploited for photonic device fabrication. In fact, carefully engineered line defects could act as waveguides connecting photonic devices in all-optical microchips, and infiltration of the photonic material with suitable liquid crystals might produce photonic bandgap structures (and hence light-flow patterns) fully tunable by an externally applied voltage. However, the realization of this technology requires a strategy for the efficient synthesis of high-quality, large-scale photonic crystals with photonic bandgaps at micrometre and sub-micrometre wavelengths, and with rationally designed line and point defects for optical circuitry. Here we describe single crystals of silicon inverse opal with a complete three-dimensional photonic bandgap centred on 1.46 microm, produced by growing silicon inside the voids of an opal template of dose-packed silica spheres that are connected by small 'necks' formed during sintering, followed by removal of the silica template. The synthesis method is simple and inexpensive, yielding photonic crystals of pure silicon that are easily integrated with existing silicon-based microelectronics.     

混合型硅胶基质高效液相色谱填料的制备与表征

以自制的高纯硅胶微球为原料,通过与二甲基十八烷基甲氧基硅烷、γ-氨丙基三乙氧基硅烷、碘甲烷等一系列物质键合,合成了一种新型的反相/离子型混合硅胶基质色谱柱填料。经元素分析、红外光谱、²⁹Si固体核磁共振和差热热重等分析手段对硅胶基质混合固定相进行了表征;以甲醇和水作为二元流动相,对尿嘧啶、苯酚、对氯硝基苯和萘进行了色谱分离。结果表明,色谱峰的不对称因子为0.95~1.10, 萘的理论塔板数92000块/m,分离度均在4.0以上。     

Template－synthesized opal hydrogels

Opal hydrogels could be synthesized with polymer inverse opal template. A pH responsive opal N-iso-propylacrylamide/acrylic acid copolymerized hydrogel was prepared as an example. The ordered structure and response to pH were investigated. Through the sol-gel process of tetrabutyl titanate, opal titania was obtained with the opal hydrogel template.     

高强度超疏水性杨木材料的构建

 针对超疏水性材料应用过程中性能不够持久的问题,以杨木为例,通过实验研究了具有高强度超疏水性能的杨木材料的构建。采用真空加压方法将二氧化硅合成原料注入杨木内部,使正硅酸乙酯、氨水、乙醇在杨木微米级导管内发生溶胶-凝胶作用而生成SiO₂纳米粒子,在不破坏杨木原本结构的情况下实现二氧化硅与木材的复合,使杨木材料形成更强健的二维多级粗糙结构,并经十八烷基三氯硅烷修饰使杨木材料表面获得高强度的超疏水性能。检测结果表明,该超疏水性杨木材料样品在水、腐蚀性液体（酸液/碱液）、常见有机溶剂中以及一些常见条件下均保持了优异的超疏水特性能。     

介孔氧化铝空心球的制备及表征

以掺氮碳球为硬模板,F127为软模板,廉价的Al(NO3)3·9H2O为铝源,成功制备出具有介孔结构的氧化铝空心球。通过SEM,N2吸附-脱附,XRD,FT-IR表征显示,其粒径大小均一,均在500nm左右;壳层具有蠕虫状的介孔结构,且主要为无定型结构的氧化铝;介孔孔径为17nm,比表面积为153m2/g,孔容为0.67cm3/g。详细讨论了介孔氧化铝空心球的形成机理。     

乙醇超临界技术制备疏水性白炭黑粉体

以硅酸钠为硅源,浓硫酸为酸化剂,在超重力旋转床中制备出二氧化硅,经处理后置于高压釜内,在分别改变溶液体积与高压釜容积比值、滤饼质量或氮气预加压条件下进行乙醇超临界干燥,制得白炭黑粉体。用接触角测定仪、透射电镜、FT-IR红外光谱、氮气吸附容量法、DBP吸油值来表征所得样品。结果表明：所得样品具有极强的疏水性,接触角大都在130°以上,当溶液体积与高压釜容积比值增大时,接触角大体呈增大趋势;当滤饼质量增加时,接触角亦增大;当氮气预加压力增大时,接触角变化规律不明显;所得样品除粒径变化不大外,分散性、比表面积、吸油值等均有规律变化。     

Influence of deposition time on the morphology and optical properties of SiO<Subscript>2</Subscript>-ZnO composite photonic crystals

SiO2 photonic crystal were successfully prepared by vertical deposition and then used as a template to fabricate SiO2-ZnO composite photonic crystals on ITO substrates by electrodeposition and subsequent calcination. A number of different deposition times were used. The morphologies of the silica opals and SiO2-ZnO composite photonic crystals were investigated by scanning electron microscopy. It was found that ZnO particles grew randomly on the surfaces of the silica spheres when the deposition time was short. As the deposition time was increased, the ZnO particles grew evenly on the surfaces of the silica spheres so that the interstitial space of the silica template was filled with ZnO particles. Reflectance spectra of the SiO2-ZnO composite crystals revealed that all of the fabricated photonic crystals exhibit a photonic band gap in the normal direction.     

ZnO:Er/Yb不同形貌纳米颗粒的制备与上转换发光性质研究

分别采用沉淀法、碱腐蚀法、模板法等3种不同的实验方法制备了不同形貌的氧化锌掺杂稀土元素纳米粉末,对所得到的样品进行了上转换光学性质分析.用X射线衍射仪对样品进行了结构分析,用扫描电子显微镜观察了粉末形貌并估算颗粒大小,用荧光光谱仪测试样品的上转换发光光谱并进行了机理分析.结果表明,纳米粉末粒径的大小影响了材料发光的性能.粒径较小的空心球结构颗粒其光学性能优于粒径较大的实心球颗粒.对于空心球结构,当粒径相对较小时,有利于红光上转换发射;而粒径较大时,有利于增强绿光上转换发射.     

酸催化二氧化硅溶胶的制备及稳定性研究

以正硅酸乙酯、水、乙醇为原料，硝酸为催化剂，制备了SiO2溶胶．研究了pH值、水量、乙醇量、反应温度、反应时间以及溶胶陈化温度等因素等对SiO2溶胶稳定性的影响，以便实现对二氧化硅溶胶稳定性的控制．实验结果表明，随着体系pH值的升高、乙醇量的增大，溶胶的凝胶时间延长，溶胶的稳定性也增强．随着体系水量的增加，溶胶的稳定性先减小后增大，在水酯摩尔比Rw=7．2时，溶胶的稳定性达到最小；随着反应温度的升高、反应时间的延长，溶胶的稳定性降低；采用较低的陈化温度有利于提高溶胶的稳定性．在溶胶粘度发生急剧变化之前溶胶是相对稳定的．     

偏高岭石与硅灰制备的高强混凝土性能比较

比较了用偏高岭石与硅灰分别制备的高强混凝土的施工性能、强度性能、收缩变形性能和抗硫酸盐侵蚀性能.试验结果表明,用偏高岭石制备的高强混凝土的施工性能优于硅灰制备的高强混凝土;在水胶比较高时,偏高岭石混凝土的强度高于硅灰混凝土强度,水胶比较低时则相反,是硅灰混凝土强度高于偏高岭石混凝土;总之,偏高岭石混凝土的自收缩和干燥收缩小于硅灰混凝土;偏高岭石混凝土的抗硫酸盐侵蚀能力不低于掺硅灰的混凝土.偏高岭石是一种可与硅灰相媲美的活性矿物掺料.     

Al2O3—SiO2溶胶制备及在水溶性聚氨酯中分散行为

电泳实验证明,不同粒径硅溶胶加入碱式氯化铝水溶液后,改性硅溶胶粒表面带正电荷,经ＥＤＳ、ＦＴ－ＩＲ证明,硅溶胶粒表面吸附了水合氧化铝,不同粒径改性硅溶胶为牛顿型流体且粘度相近,分散在聚氨酯－脲－胺乙酸盐（ＰＵ－Ｅ）中,仍是牛顿型流体,分散体系粘度增加,表明改性交粒表面未吸附ＰＵ－Ｅ,也反映了硅溶胶粒表面已完全为水合氧化铝所包覆。     

多功能复合微球及中空微球的制备与性能

摘要：采用磺化聚苯乙烯（Ps）微球为模板制备出了以Fe304-PANi（聚苯胺）为壳,PS为核的具有核壳结构多功能Fe304．PANi／PS复合微球．采用溶剂抽提溶解去除Ps核得到Fe304．PANi具有导电导磁双功能中空微球．中空微球空腔尺寸大小一致,约为190nm,壳层厚度约30nm．通过控制Ps模板磺化时间来同步控制微球空腔大小和微球壳层厚度．Fe304-PANi／PS复合微球及中空微球具有良好的导电性和超顺磁性．所制备的中空Fe304微球及中空Fe304-PANi微球对模拟污水浊度去除率分别达到84．2％及86．9％．