小角X射线散射法测定溶胶平均界面厚度

溶胶界西层厚应通常是用Porod法对高角区负偏离的队Porod曲线进行拟合求算,但本文研究表明还可通过分别测定Porod负偏离校正前后体系粒子的平均阗径之差而获得平均界面厚度。应用上述方法测定了在不同制备条件下制备的二氧化硅溶胶的平均界面厚度。     

利用小角X射线散射技术研究组分对聚酰亚胺/Al2O3杂化薄膜界面特性与分形特征的影响

采用溶胶-凝胶方法制备无机纳米杂化聚酰亚胺(PI),应用同步辐射小角X射线散射(SAXS)方法研究不同组分杂化PI薄膜的界面特性与分形特征.研究结果表明:散射曲线不遵守Porod定理,形成负偏离,说明薄膜中有机相与Al₂O₃纳米颗粒间存在界面层,界面层厚度在0.54 nm到1.48 nm范围内;随无机纳米组分增加,界面层厚度增加,有机相与无机相作用变强;无机纳米颗粒同时具有质量分形和表面分形特征,其分布、集结是一种非线性动力学过程;随组分增加,其质量分形维数降低 关键词： 小角X射线散射 纳米杂化 聚酰亚胺 界面     

用小角X射线散射法研究溶胶结构

采用溶胶凝胶方法在碱性条件下制备了SiO2和ZrO2溶胶,应用同步辐射小角X射线散射(SAXS)法研究了溶胶的结构.结果表明,溶胶粒子是多分散的,其生长、聚集受RLCA和Eden模型的共同控制,是一种非线性的动力学过程,所形成的聚集体呈随机、分岔、稠密不同的结构,具有质量分形的特征.同时还发现所研究溶胶的散射曲线均不遵守Porod定理,形成负偏离或正偏离,这说明在溶胶粒子与分散介质间有过渡相存在.对上述偏离进行了定性和定量的分析,提出了正偏离时的定量解析方法,从而得到了胶体系统中有关过渡层(界面层)结构的 关键词：     

小角x射线散射法研究氧化硅溶胶的制备环境依赖性

根据氧化硅溶胶的不同制备环境(如老化时间、酸碱性和溶剂种类等)，利用小角x射线散射( SAXS)技术，辅以动态光散射等方法，对氧化硅溶胶的界面性质和微结构进行比较性分析.发 现在碱或酸催化下氧化硅溶胶的SAXS结果表现出极大差异，用低分子有机酸作催化剂不仅可 以得到聚硅氧烷大分子，而且有机酸和正硅酸乙酯的酸解反应使溶胶形成内部结构很复杂的 颗粒悬浮体系.溶剂极性越大，则颗粒形貌越不规则.甲酸酸解得到的溶胶颗粒的硅氧四面体 形成程度是所有体系中最差的.发现了在水为溶剂时溶胶SAXS结果中不同寻常的正、负偏离 共存情况，并给出了相应的解释. 关键词： 小角x射线散射 氧化硅 溶胶_凝胶     

小角x射线散射结晶聚合物过渡层厚度的测定

由于结晶聚合物中的过渡层是弥散的，而修正的Porod定律是解决这种问题的有效方法之一. 把相关函数法和Porod定律法求结晶聚合物的过渡层厚度进行了比较，它们的计算结果是一致的. 关键词： 小角x射线散射 结晶聚合物 过渡层厚度 相关函数法 Porod定律     

三氨基三硝基苯材料微孔结构的小角x射线散射实验研究

应用同步辐射x射线小角散射技术研究了不同工艺制备的三氨基三硝基苯样品中的微孔状况 ，得到了样品材料有关微结构参数，包括微孔平均孔径及孔径分布、分形特征、Porod常数 及界面参数等，并分析了微孔结构参数的变化规律.结果表明，不同工艺制备的TATB样品材 料其微孔结构有较大差别，都有较显著的特征. 关键词： 小角x射线散射 TATB材料微孔分布     

透光导电ITO膜的制备及其光电特性的研究

采用溶胶-凝胶方法制备ITO膜,并从制备工艺上研究了各种因素对ITO膜光电特性的影响.最后制出的ITO膜厚度约为50nm,在可见光区平均透射比达97%,最高达99.55%,电阻率在2.0Ω·cm左右,最低达到0.31Ω·cm.     

超顺磁性氧化铁-胶束体系的制备和T2弛豫增强作用 

制备了在负离子型胶束十二烷基硫酸钠（SDS）、羧甲基纤维素钠（CMC），正离子型胶束十六烷基三甲基溴化铵（CTAB）和非离子型胶束Triton X-100、PEG-400中的氧 化铁粒子(SPIO)溶胶分散体系. 测定了这些SPIO胶束体系水质子的横向弛豫时间T₂, 并讨论了不同胶束性质对T₂的影响. 对PEG-400分散SPIO溶胶体系进行了动物急性毒性测试和活体T₂加权成像实验. 结果表明：该溶胶体系无明显急性毒性，且对大鼠肝区有显著的负增强.     

聚苯乙烯-聚丁二烯嵌段共聚物的固体NMR研究

采用我们前期发展的测定多相高聚物中界面相厚度及相区尺寸的NMR新方法对两种不同嵌段结构的聚苯乙烯-聚丁二烯嵌段共聚物进行了研究,并与关于界面相厚度的高分子物理理论结果进行对比. 该NMR方法采用偶极滤波-自旋扩散技术分别测定非界面相的柔性区与界面相中质子的百分含量,然后根据界面相与柔性相的几何关系计算界面相厚度. 研究结果表明这两种嵌段共聚物具有几乎相同的界面相厚度,该结果与Helfand等人关于多相高聚物中界面相厚度的自洽场理论预言基本符合.     

小角X射线散射方法测定二氧化硅干凝胶的平均孔径

提出了当多孔体系的小角X射线散射不遵守Porod定理的情况下,应用Debye法(相关函数法) 和Guinier法(逐级切线法和多级斜线法)计算它们的平均孔径的方法.对不同制备条件下部分 二氧化硅干凝胶的测试,取得了比较一致的结果,并与氮气吸附法测定结果进行了对比. 关键词： 小角X射线散射 二氧化硅干凝胶 平均孔径     

STUDY OF MESOPOROUS SILICA MATERIALS BY SMALL ANGLE X-RAY SCATTERING

Small angle X-ray scattering experiments have been performed to study the microstructure of mesoporous silica materials prepared by condensation of tetraethylorthosilicate using non-ionic alkylpolyethyleneoxide (AEO₉) and ionic cetyltrimethylammonium bromide (CTAB) surfactant as templates. It is the pores within the nanometre range that produce the main scattering. The scattering of the pure silica systems obey Porod's law. The scattering of the systems with templates remaining in the pores show positive deviations from Porod's law. This may be because the templates produce some additional scattering background and then make the scattering of pores distorted. The results show that the full removal of templates from the pores of the materials by Soxhlet extraction is very easy for AEO₉, but it is difficult for CTAB. The positive deviation correction is also performed.     

水雾包裹沙尘颗粒核壳结构的散射特性研究

基于离散偶极子近似法(DDA),对水雾包裹沙尘颗粒的核壳结构光学特性进行研究,计算了长短轴比例为2∶1的椭球形粒子的核壳结构内、外层厚度及散射角度变化对光散射特性的影响。结果表明,内核大小不变,外层厚度由1.2 μm增大到4.8 μm,核壳双层颗粒散射系数和消光系数由3.4和3.43降低到2.543和2.545,且散射相对强度也明显增大。外层厚度不变,内核厚度由0.6 μm增加到2.4 μm,散射系数和消光系数由3.105和3.111变化为2.76和2.9;可见外层厚度对核壳双层颗粒散射特性的影响更大,这是由于散射光主要与外层物质相互作用引起的。散射相对强度随波长的增加而降低,随核壳结构尺度的增加呈现递增的规律。该结果对大气中气溶胶和水雾共同作用时的散射特性,激光在其中的传输特性等研究有参考价值。     

溶胶-凝胶TiO2和SiO2光学膜的结构

本文研究了TiO₂和SiO₂溶胶-凝胶光学膜在低温热处理下的组分、形貌特征、光散射特性.AES分析结果表明,在TiO₂膜和SiO₂膜的交界面处,Ti和Si相互扩散,从而证实了在多层膜中,膜层之间、膜层和基底之间有Ti-O-Si(或Si-O-Ti,或Si-O-Si)化学键形成.AES和ESCA分析结果显示溶胶-凝胶膜经过低温处理后C的含量较高,这归结为溶胶—凝胶膜的工艺特点.AFM测试结果显示,溶胶—凝胶TiO₂光学膜的表面形貌具有显著的柱状结构,薄膜表面起伏大约是7.5nm.TiO₂,SiO₂单层膜的表面散射率随着热处理温度的提高而变大,对于不同陈化时间的溶液镀制的膜有不同的表面散率.     

Most probable and average energy losses of the beam of monoenergetic charge particles with average and low energies at multiple scattering

The results of statistical modeling of the discrete process of multiple inelastic scattering are presented. This process is modeled to find the most probable and average energy losses of a beam of charged particles (electrons and protons) passing through a material layer with a given thickness. The proposed approach is based on determining the most probable energy loss at single small-angle scattering, on including the effect of the statistical probability on this quantity at multiple scattering, and on determining the average number of inelastic interactions for particles in a film with a known thickness. The dependence of the particle energy lost during interaction with atomic electrons on their relative motion is taken into account for low-energy particles. A new interpretation is offered for the parameter J in the logarithmic term in the formulas for the average and most probable energy losses of charged particles. A computational scheme for this parameter as an average potential energy of atomic electrons is given.     

Optical properties of composites with nanodimensional oxide coatings versus the properties of film-forming sols. I. The influence of sol’s oxide composition

The influence of the aging period (duration) and the aging-related rheological characteristics of film-forming solutions (sols) on the refractive index and thickness of coatings, light reflection and light transmission coefficients, and optical losses in glass substrate-nanodimensional oxide (CuO-TiO₂) composites is considered. It has been shown that the increase in the CuO concentration in the coating and the extension of the sol aging period favor crystallization and change the form of inclusions in the coating from pseudospherical to dendritic with a different degree of branching. The refractive index of the film and its related coefficient of mirror reflection of the composite are functions of the density of packing sol disperse-phase particles into a nanodimensional layer. The packing density of dendritic particles drops decreases with the degree of their branching and transverse size of fragments. In every case, an optimal sol aging period should be found to obtain glass composites with nanodimensional coatings offering desired optical properties.     

Modelling self-assembling of colloid particles in multilayered structures

Simulations of particle multilayer build-up in the layer by layer (LbL) self-assembling processes have been performed according to the generalized random sequential adsorption (RSA) scheme. The first (precursor) layer having an arbitrary coverage of adsorption centers was generated using the standard RSA scheme pertinent to homogeneous surface. Formation of the consecutive layers (up to 20) was simulated by assuming short-range interaction potentials for two kinds of particles of equal size. Interaction of two particles of different kind resulted in irreversible and localized adsorption upon their contact, whereas particles of the same kind were assumed to interact via the hard potential (no adsorption possible). Using this algorithm theoretical simulations were performed aimed at determining the particle volume fraction as a function of the distance from the interface, as well as the multilayer film roughness and thickness as a function of the number of layers. The simulations revealed that particle concentration distribution in the film was more uniform for low precursor layer density than for higher density, where well-defined layers of closely packed particles appeared. On the other hand, the roughness of the film was the lowest at the highest precursor layer density. It was also predicted theoretically that for low precursor layer density the film thickness increased with the number of layers in a non-linear way. However, for high precursor layer density, the film thickness increased linearly with the number of layers and the average layer thickness was equal to 1.58 of the particle radius, which is close to the closely packed hexagonal layer thickness equal to 1.73. It was concluded by analysing the existing data for colloid particles and polyelectrolytes that the theoretical results can be effectively exploited for interpretation of the LbL processes involving colloid particles and molecular species like polymers or proteins.     

超细SnO_2纳米晶粒带边光吸收的线度效应

采用超细过滤方法 ,分别制备含有平均线度小于 2nm的超细SnO2 纳米晶粒的酸性和碱性溶胶溶液 .通过动态光散射、X射线衍射和晶粒透射电子显微镜像测量 ,确定了SnO2 晶粒的线度 .对其光吸收谱测量发现 ,超细过滤后酸性和碱性溶胶溶液中晶粒的带边光吸收能量均有明显蓝移 .分析结果表明 ,SnO2 晶粒的线度减小是同类晶粒带边光吸收蓝移的主要原因 .