Eu(TTFA)3掺杂SiO2杂化胶体球的合成及特性

采用改进的碱催化法和种子法分别制得了稀土配合物Eu(TTFA)₃掺杂的SiO₂杂化胶体球,并用透射电子显微镜和荧光分光光度计对其显微形貌和荧光光谱特性进行了详细地研究.结果表明,两种方法都可以获得单分散性的、稀土配合物掺杂SiO₂杂化胶体球,且都具有Eu³⁺离子典型的荧光光谱特性.Eu(TTFA)₃掺杂入SiO₂胶体球中后,有机配体TTFA在短波长处的吸收明显增强了,最大的吸收峰位也向短波长方向移动大约20～30 nm,Eu³⁺离子5D0→7F2发射跃迁仍然具有良好的窄线发光特征,同时荧光峰值的形态和位置受SiO₂基体的影响发生轻微的变化.     

低成本溶胶-凝胶法制备SiO2/TiO2双层膜的减反射与自清洁性能

将玻璃基底依次在低成本的SiO₂溶胶和TiO₂溶胶中浸渍后,在500 oC下煅烧制备了同时具备减反射与自清洁性能的SiO₂/TiO₂双层膜．该膜的光学性能与结构特征分别通过紫外-可见分光光度计和场发射扫描电镜进行了表征．同时,源于超亲水性和光催化作用的自清洁性能也凸显出来．实验结果表明制备SiO₂/TiO₂双层膜对光的透射率最高可达到95%,同时具备自清洁性能．     

压力对纳米CoFe2O4/SiO2复合材料结构的影响

 采用溶胶-凝胶工艺和高温高压实验技术,制备了纳米CoFe₂O₄/SiO₂复合材料。利用X射线衍射仪、扫描电子显微镜和振动样品磁强计,对样品的结构、微观形貌和磁性进行了研究,并对CoFe₂O₄中阳离子的占位情况进行了讨论。结果表明,随着处理压力的升高,样品的晶粒尺寸增大,晶格常数减小,比饱和磁化强度增大。通过计算结果可以推断,压力的升高导致CoFe₂O₄中的部分Fe³⁺从A位移向了B位,而部分Co²⁺则从B位移向了A位。     

非晶态SiO2的高温高压转变研究

利用金刚石对顶砧高压装置和激光双面加热技术, 以经700°C热处理后的吉林长白山硅藻土作为非晶态SiO₂样品,在0—4GPa, 1000—1300K温压条件下开展同步辐射X射线衍射原位测试(EDXD方法), 研究非晶态SiO₂在高温高压条件下的结晶转变方式. 测试结果表明, 在0.8—2.4GPa, 1000—1300K温压条件下, 非晶态SiO₂转变成α-石英而非β-石英或方石英, 其结晶温度较常压下非晶态SiO₂晶化所需温度明显较低, 表明压力有利于降低非晶态SiO₂转变的活化能, 并与常压下的结晶产物不同. 在3—4GPa, 1300K温压条件下, 非晶态SiO₂和石英均转变成了柯石英.     

焙烧温度对SiO2负载的Co3O4纳米粒子表面氧缺陷浓度和CO氧化催化性能的影响

以传统的浸渍法,在不同焙烧温度下制备了用于CO氧化反应的Co₃O₄/SiO₂催化剂．通过激光拉曼光谱(Raman)、X射线光电子能谱(XPS)、X射线衍射(XRD)、程序升温还原(TPR)和X射线吸收精细结构谱(XAFS)表征了该系列催化剂的结构．在所有的催化剂中,XRD和Raman光谱都只检测到了Co₃O₄晶相的存在．与Co₃O₄体相相比,XPS结果表明在200 oC焙烧的(Co₃O₄(200)/SiO₂)催化剂中Co₃O₄表面上存在着过量的Co²⁺．与XPS的结果一致,TPR结果表明Co₃O₄(200)/SiO₂催化剂中Co₃O₄表面上存在氧缺陷, 并且XAFS结果也表明Co₃O₄(200)/SiO₂催化剂中Co₃O₄具有更多的Co²⁺．提高焙烧温度使得过量的Co²⁺进一步氧化为Co³⁺,同时降低了表面氧缺陷浓度,从而得到计量比的Co₃O₄4/SiO₂催化剂．在所有的负载催化剂中Co₃O₄(200)/SiO₂催化剂表现出了最好的CO氧化催化性能,表明过量Co²⁺和表面氧缺陷的存在能够促进Co₃O₄催化CO氧化反应的活性.     

层间热处理对SiO2/ZrO2双层膜的影响

 以正硅酸乙酯和丙醇锆为前驱体,用溶胶-凝胶法在K9基片上提拉镀制SiO₂/ZrO₂双层膜。采用不同实验步骤制备了2个样品,样品1镀完SiO₂后直接镀ZrO₂ ,样品2镀完SiO₂经热处理后再镀ZrO₂。采用原子力显微镜、椭偏仪、紫外-可见分光光度计对薄膜进行表征。针对SiO₂/ZrO₂双层膜,考虑到膜间渗透的影响,采用３层Cauchy模型进行椭偏模拟,椭偏参数的模拟值曲线与椭偏仪的测量值曲线十分吻合,进而发现热处理可以使SiO₂/ZrO₂双层膜之间的渗透减少近23 nm,从而提高其峰值透射率。利用输出波长1.064 mm,脉宽8.1 ns的激光束对样品进行了损伤阈值的测试,用光学显微镜观察损伤形貌,结果发现两者损伤阈值分别为13.6 J/c2和14.18 J/cm²,均为膜的本征损伤。     

H2O2水热合成双峰介孔硅MCM-48球

在温和的条件下,通过H₂O₂水热处理预合成的MCM-48,得到了有序的双峰介孔硅MCM-48球． 结果表明H₂O₂对于同时去除有机模板剂及形成双峰介孔硅MCM-48球具有重要的作用．采用XRD、TEM、FT-IR和N₂吸附-解吸等方法对双峰介孔MCM-48材料进行了表征,对双峰介孔MCM-48的形成机理也进行了探讨．     

SiO2/Si衬底上石墨烯的制备与结构表征

在分子束外延(MBE)设备中,利用直接沉积C原子的方法在覆盖有SiO₂的Si衬底(SiO₂/Si)上生长石墨烯,并通过Raman光谱和近边X射线吸收精细结构谱等实验技术对不同衬底温度(500℃,600℃,700℃,900℃,1100℃,1200℃)生长的薄膜进行结构表征.实验结果表明,在衬底温度较低时生长的薄膜是无定形碳,在衬底温度高于700℃时薄膜具有石墨烯的特征,而且石墨烯的结晶质量随着衬底温度的升高而改善,但过高的衬底温度会使石墨烯质量降低.衬底温度为1100℃时结晶质量最好.衬底温度较低时C原子活性较低,难以形成有序的C-sp²六方环.而衬底温度过高时(1200℃),衬底表面部分SiO₂分解,C原子与表面的Si原子或者O原子结合而阻止石墨烯的形成,并产生表面缺陷导致石墨烯结晶变差.     

纤维状TiO2/Bi2O3光催化剂的制备及其光催化性能

以C₁₆H₃₆O₄Ti和Bi(NO₃)·5H₂O为原料,以棉花纤维为生物模板,合成了系列纤维状TiO₂/Bi₂O₃光催化剂．采用XRD、SEM、UV-Vis等测试技术对样品的相结构、形貌和吸光性能等进行了表征分析．结果表明,样品中的Bi₂O₃为单斜相和四方相共存的混晶,纤维长度达到毫米级,     

利用聚乙烯亚胺修饰的CaCO3仿生模板合成3D花朵型二氧化硅微球

利用聚乙烯亚胺(PEI)修饰的碳酸钙仿生模板合成了具有3D花朵型形貌的SiO₂微球.通过调整碳酸钙微粒表面不同浓度PEI的吸附量实现SiO₂微球的形貌控制呈现花朵或刀锋的形状. 用XPS和SEM对制备的SiO₂微粒进行表征. 结果表明,不用浓度的PEI修饰可以较好地控制3花朵型DSiO₂微球的形貌.     

Discrimination of Smoke Particles Using Infrared Photoelectrical Detection

A method of discrimination of smoke particles using infrared photoelectrical detection is proposed in this paper. Principle of the method is that smoke particles of different materials have different scattering light intensities at same scattering angle according to Mie Theory. Facility used to realize the method includes an infrared laser as light source and an array of avalanche photodiodes distributed at assigned angles as sensing devices. Scattered light signal at these angles are collected and processed. Categories of smoke particle are discriminated by signal processing results. Experiments show that by using this method cigarette smoke, kerosene smoke and water vapor can be discriminated with rate of discrimination of greater than 95%. Application of this technology in the field of fire detection will eliminate some effects of human activities such as cigarette smoking and steam on smoke detection, and improve sensitivity as well as reliability of smoke detection.     

Band structure of photonic crystal fibers with silica rings in triangular lattice

The characteristics of the cladding band structure of air-core photonic crystal fibers with silica rings in triangular lattice are investigated by using a standard plane wave method. The numerical results show that light can be localized in the air core by the photonic band gaps of the fiber. By increasing the air-filling fraction, the band gap edges of the low frequency photonic band gaps shift to shorter wavelength, whereas the band gap width decreases linearly. In order to make a specified light fall in the low frequency band gaps of the fiber, the interplay of the silica ring spacing and the air-filling fraction is also analyzed. It shows that the silica ring spacing increases monotonously when the air-filling fraction is increased, and the spacing range increases exponentially. This type fiber might have potential in infrared light transmission.     

二氧化硅纳米颗粒与碳黑纳米颗粒红外漫反射光谱的测量与分析

用FTIR-FTS3000光谱仪和漫反射附件分别采集了二氧化硅纳米颗粒、炭黑纳米颗粒和二氧化硅纳米颗粒与碳黑纳米颗粒的不同配比的混合样品的红外漫反射光谱。通过对测量结果的分析,发现二氧化硅纳米颗粒的红外漫反射光谱较之体材料有蓝移和宽化现象,此现象可以用纳米粒子的小尺寸效应和量子尺寸效应来进行初步解释。而碳黑纳米颗粒因为其强吸光性的原因,实验中没有得到理想的光谱。混合样品中,碳黑纳米颗粒有一个最大吸收临界浓度,此时二氧化硅纳米颗粒与碳黑纳米颗粒的质量比是100∶20。在这个比例以内,碳黑纳米颗粒的特征峰位的F(R)函数与浓度符合朗伯-比尔定律。当碳黑纳米颗粒在体系中的含量超过这个比值,随着碳黑在体系中比例的增加,吸光度将不再增大。     

Synthesis of Nanometer Glass and Crystal Particles by Excimer Laser Ablation

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卷云冰晶粒子散射相函数的展开系数研究

冰晶粒子散射相函数的多项式展开可以应用于卷云条件下大气辐射传输模式的计算。本文利用广义球函数对表面严重粗糙的冰晶粒子相函数进行展开,并对表面严重粗糙的实心棱柱模型、实心棱柱聚合物模型和一般种类混合模型3种冰晶粒子的展开系数特性进行分析研究,数值计算结果表明了广义球函数对表面严重粗糙的冰晶粒子多项式展开的有效性。     

Preparation and size control of highly monodisperse vinyl functionalized silica spheres

Vinyl functionalized silica spheres (VFSSs) are prepared by one-step reaction using the aqueous solution of organosilane. The synthetic method is effective and reproducible with one process used. The VFSSs could self-assemble into three-dimensional (3D) fcc photonic crystals. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the VFSSs were highly monodisperse and their surfaces were sufficiently smooth. The size of the VFSSs could be controlled by adjusting the reaction temperature. The sphere size reached its minimum, 394 nm, around 45 °C and became larger when the temperature was either elevated or lowered. The maximum sphere size, 515 nm, was obtained around 15 °C. This work is expected to extend to the preparation and size control of other kinds of hybrid silica spheres.     

Slow light in photonic crystals waveguide constructed with symmetrically perturbed structure

Symmetrically perturbed photonic crystal waveguide can be constructed by inserting perturbative dielectric rods into photonic crystal waveguide structure with whose rods’ radius distributed according to a certain proportion. Slow light properties in this new structure are studied by using the plane wave expansion method (PWM). In this paper, schemes of adjusting radius of perturbative dielectric rods and adjusting the dielectric constant of perturbative dielectric rods are proposed to optimize slow light properties. The result shows that the scheme for adjusting radius of perturbative rods can realize larger average slow light bandwidth and efficiently control the NDBP value of the waveguide, but it contributes little to obtain smaller group velocity. The scheme for adjusting dielectric constant of perturbative rods can realize smaller group velocity, but can only obtain smaller slow light bandwidth and cannot efficiently enlarge NDBP value of waveguide. Both optimization schemes proposed in this paper realize group velocity that is two magnitudes smaller than the vacuum speed of light meanwhile maintaining large NDBP and low GVD region. Our results provide important theoretical basis for the potential application offered by symmetrically perturbed photonic crystal in future optical networks.     

Numerical demonstration of slow light tuning in slotted photonic crystal waveguide using microfluidic infiltration

Tuning of the operating wavelength of slow light in the slotted photonic crystal waveguide using microfluidic infiltration has been investigated. Using 2D plane wave expansion method, we numerically demonstrate that the operating wavelength can be shifted from the C to L band, simply by choosing the refractive index of the infiltrated fluid. It is also found that, as the refractive index of the infiltrated fluid changes, the group velocity dispersion has slight variation at different operating wavelength. This design opens the possibility for post-fabrication scheme of tuning the operating wavelength of slow light in slotted photonic crystal waveguide, and allows the device to be optimized for different applications.