内表面掺硅聚苯乙烯空心微球初步研究

靶丸内表面掺杂诊断元素可以为内爆压缩界面的研究提供必要的手段。以二甲基二乙氧基硅烷为原料，利用乳液微封装技术和界面聚合技术可以实现单一内表面掺硅的空心聚苯乙烯微球的制备。X光照相和X能谱分析表明:内表面掺硅量比外表面高出2~3个数量级。均匀内表面掺硅层的厚度小于0.3μm，掺杂层厚度越小，均匀性越好。     

微晶硅n-i-p太阳电池中n型掺杂层对本征层结构特性的影响

采用高压射频等离子体增强化学气相沉积方法在非晶和微晶两种n型硅薄膜衬底上沉积了一系列不同厚度的本征微晶硅薄膜,研究了不同n型硅薄膜对本征微晶硅薄膜的表面形貌、晶化率和结晶取向等结构特性的影响.结果表明,本征微晶硅薄膜结构对n型掺杂层具有强烈的依赖作用,微晶n型掺杂层能够有效减少n/i界面非晶孵化层的厚度,改善本征微晶硅薄膜的纵向均匀性,进而提高微晶硅n-i-p太阳电池性能. 关键词： 孵化层 微晶硅薄膜 纵向均匀性 n-i-p太阳电池     

掺硫聚苯乙烯空心微球小面积XPS分析

 在靶丸内表面掺杂诊断元素可以为内爆压缩界面的研究提供必要的手段，因此确定聚苯乙烯微球的元素含量特别是掺杂元素的含量对于靶丸的性能研究有重要的意义。采用小面积X射线光电子能谱（SAXPS）分析技术，对直径为150 mm，掺硫的单一聚苯乙烯微球的内外表面进行了测试，获得了微区内的元素及元素含量，发现硫主要存在于微球内表面。同时对该微球的制造过程进行了分析，认为XPS分析结果与工艺状态一致。     

大尺寸多孔硅／硝酸盐复合材料的制备

多孔硅是一种具有特殊物理形态的硅单质材料，呈海绵状结构，内部存在大量的纳米孔洞，孔洞表面有一层具有原子直径厚度的氢原子层，这个氢原子层在硅原子和充填在孔洞内的硝酸盐分子之间起着缓冲和隔离作用。在一定的触发条件下，可以发生快速的氧化还原反应，纳米孔洞结构使得多孔硅与硝酸盐之问的界面面积非常大，反应速度非常快，反应释放能量是TNT的7倍，这使得多孔硅／硝酸盐复合材料成为一种潜在的含能材料。     

Si掺杂对AlGaInP/GaInP多量子阱性能的影响

采用LP-MOCVD技术在n-GaAs衬底上生长了AlGaInP／GaInP多量子阱红光LED外延片。以X射线双晶衍射技术和光致发光技术对外延片进行了表征,研究了Si掺杂对AlGaInP／GaInP多量子阱性能的影响。研究表明：掺Si能大大提高(Al0．3Ga0.7)0.5In0.5P／Ga0.5In0.5P多量子阱的发光强度。相对于未故意掺杂的样品,多量子阱垒层掺Si使多量子阱的发光强度提高了13倍,阱层和垒层均掺Si使多量子阱的发光强度提高了28倍。外延片的X射线双晶衍射测试表明,Si掺杂并没有使多量子阱的界面质量变差。     

In掺杂ZnO薄膜的制备及其特性研究

采用射频反应溅射技术在硅(100)衬底上制备了未掺杂和掺In的ZnO薄膜。掠角X射线衍射测试表明,实验中制备的掺In样品为ZnO薄膜。用X射线衍射仪、原子力显微镜和荧光分光光度计分别对两样品的结构、表面形貌和光致发光特性进行了表征,分析了In掺杂对ZnO薄膜的结构和发光特性的影响。与未掺杂ZnO薄膜相比,掺In ZnO薄膜具有高度的C轴择优取向,同时样品的晶格失配较小,与标准ZnO粉末样品之间的晶格失配仅为0．16％;掺In ZnO薄膜表面平滑,表面最大不平整度为7nm。在掺In样品的光致发光谱中观察到了波长位于415nm和433nm处强的蓝紫光双峰,对掺In样品的蓝紫双峰的发光机理进行了讨论,并推测出该蓝紫双峰来源于In替位杂质和Zn填隙杂质缺陷。     

毛细管X光透镜共聚焦技术在测厚中的应用

为了实现对薄膜和镀层材料厚度的微区无损分析,利用多毛细管X光会聚透镜和多毛细管X光平行束透镜设计并搭建了普通实验室X射线光源的共聚焦微束X射线荧光测厚仪,对该共聚焦测厚仪的性能进行了系统表征。利用该测厚仪测定了厚度约为25μm的Ni独立薄膜样品和压于硅基表面厚度约为15μm的Ni薄膜样品厚度,对应它们的相对测量误差分别为3.7%和6.7%。另外,还对厚度约为10μm Ni薄膜样品的厚度均匀性进行了测量。该共聚焦测厚仪可以对样品进行微区深度分析,并且具有元素分辨能力,从而使得该谱仪可以测量多层膜样品不同层的膜厚,在薄膜和镀层厚度表征领域具有潜在的应用。     

磁控溅射结合脉冲激光制备钛掺杂硅薄膜的研究（英文）

发展了一种改进的新型超掺杂工艺,通过真空磁控溅射多层镀膜后结合532nm波长可见纳秒脉冲激光熔融处理,进行超掺杂钛的硅薄膜材料的制备,并对材料的超掺杂层的性质和红外吸收性能进行了探究.结果表明,硅膜层中掺杂的钛原子的百分比浓度超过1%左右,对应钛原子浓度约为5×10~(20) cm~(-3)左右,超过钛在硅中形成超掺杂所对应的原子浓度.钛超掺杂层的厚度超过200nm左右,相对传统工艺具有明显提升,并且钛原子的浓度变化范围不超过20%,分布比较均匀.小角度X射线衍射测试表明经过可见脉冲激光熔融处理后的硅薄膜层材料结晶度为25%左右,呈多晶结构.同时红外吸收谱测试表明,样品的钛掺杂硅膜层在大于1 100nm波长的区域具有很高的红外吸收效果,最高的红外吸收系数达到1.2×10~4 cm~(-1),远超过单晶硅材料.具有比较明显的亚能带吸收的特征,呈现出Ec-0.26eV的掺杂能级.霍尔效应测试表明硅膜层具有较高的载流子浓度,超过了8×10~(18)cm~(-3).     

Mo/Si软X射线多层膜的界面粗糙度研究

 用磁控溅射法分别制备了以Mo膜层和Si膜层为顶层的Mo/Si多层膜系列, 利用小角X射线衍射确定了各多层膜的周期厚度。以不同周期数的Mo/Si多层膜的新鲜表面近似等同于同一多层膜的内界面，通过原子力显微镜研究了多层膜界面粗糙度随膜层数的变化规律。并在国家同步辐射实验室测量了各多层膜的软X射线反射率。研究表明：随着膜层数的增加，Mo膜层和Si膜层的界面粗糙度先减小后增加然后再减小，多层膜的峰值反射率先增加后减小。     

非均匀介质红外辐射传输模型

本文建立镜反射不透明表面下,非均匀光学物性纯吸收性介质内的红外辐射传输模型.红外辐射在折射率连续变化的介质内沿曲线传输.将非均匀介质沿厚度方向离散成n个物性均匀的等温微层,每个微层内辐射沿直线传播,光滑曲线传输路径即离散成首尾相连的折线系列.采用多层辐射传输模型,利用射线踪迹法建立非均匀介质内的红外辐射传输模型.在多层模型中,相邻两微层间的界面引入折射/全反射判据,避免了界面处的积分奇异现象和原本不存在的界面反射现象.     

点火靶尺度聚苯乙烯空心微球的球形度

为提高惯性约束聚变(ICF)点火靶尺度(约2mm)聚苯乙烯(PS)空心微球的球形度,研究了油相与外水相界面张力、初始油相质量分数和固化旋转流场转速对PS微球球形度的影响。结果表明,将双重乳液体系外水相中的表面活性剂聚乙烯醇(PVA)替换为聚丙烯酸(PAA)后,油相与外水相之间的界面张力增大了约10倍,PS空心微球的球形度显著提高,球形偏离度小于1μm的微球比例由5%增加至约50%;但是,在较宽范围内改变油相初始质量分数及旋转固化流场转速,对PS微球球形度的影响并不显著,球形偏离度值小于1μm的PS微球比例介于40%~60%之间。     

Template synthesis of nanostructured silica with hollow core and mesoporous shell structures

Silica capsules with hollow macroporous core–mesoporous shell (HCMS) were synthesized through template-assisted replication of submicrometer-size polystyrene spheres as templates. The silica mesoporous shell exhibited highly ordered hexagonal structure as confirmed by X-ray diffraction pattern and TEM image. The pore diameter and BET surface area of this sample were found to be 2.1 nm and 1387 m²/g, respectively.     

The effect of nanoparticles on the surface hydrophobicity of polystyrene

The surface hydrophobicity of polystyrene-nanoparticle nanocomposites has been investigated as a function of the nanoparticle content. The addition of hydrophobically coated nanoparticles in polystyrene increased the contact angle θ of a water drop with respect to that on polystyrene surface due to change of surface composition and/or surface roughness. When the nanoparticles dispersed well in the polymer, cos θ decreased linearly with increasing amount of nanoparticles indicating a composite surface consisting of smooth polystyrene regions and rough nanoparticle regions. In case of formation of nanoparticle aggregates in polystyrene, cos θ decreased sharply at a critical concentration of nanoparticles. The observed behaviour was modeled in terms of a transition from Wenzel regime to Cassie-Baxter regime at a critical roughness length scale below which the Laplace pressure prevented the penetration of the water drop into the surface undulations. We argue that multiple length scales are needed below the critical roughness length scale to increase the contact angle further by decreasing the fraction of surface area of solid material (increasing the fraction of surface area of air) underlying the water drop.     

Study of the polymer surfaces with improved resolution FRES

We have developed a time-of-flight detector system which improves the resolution of standard He⁺ forward recoil spectrometry (FRES) to better than 300 Å. The technique was used to determine the shape of the concentration profile at the surface of polymer blends of deuterated polystyrene (d-PS) and protonated polystyrene (PS). The results are discussed in terms of the predictions of mean field theories.     

The Size Distribution of Core Shell Polymeric Capsules as Revealed by Low-Field NMR Diffusometry

Time-dependent diffusion studies have been done on hexadecane molecules confined inside core shell polystyrene capsules in order to extract capsule-size distribution. The polymeric capsules were prepared by an emulsification–diffusion technique. The nuclear magnetic resonance (NMR) diffusometry technique implemented in our investigations is the so-called pulse gradient stimulated echo technique. With this technique, diffusion times between 20 and 500 ms could be probed. The distribution of the apparent diffusion coefficients was extracted using a numerical Laplace inversion. These data allowed us to obtain dimension distributions in good agreement with the direct observations from electron micrographs.     

Nanosphere embedding into polymer surfaces: a viscoelastic contact mechanics analysis

Teichroeb and Forrest [Phys. Rev. Lett. 91, 016104 (2003)] image gold nanosphere embedment into a polystyrene surface and imply the existence of a liquid surface layer. We use a viscoelastic contact mechanics model of their results to give a contrary interpretation. The surface interactions between gold and polystyrene and the indentation depth determine the loads on the nanospheres. Using bulk properties, quantitative agreement between the model and the data is obtained, implying little or no depression in the glass temperature or existence of a liquid layer at the polystyrene surface.     

Hematite/Polystyrene Raspberry-Like Microcomposites as Stable Support for Silver Nanoparticle Immobilization

Among the methods utilized for the preparation of raspberry-like microcomposites, due to its simplicity and universality, the electrostatically-driven deposition of nanoparticles at the surface of microparticles is especially attractive. This process, leading to the formation of a single nanoparticle monolayer, is widely reported. On the other hand, no data concerning the electrostatically-driven formation of nanoparticle bilayers at the surface of microparticles are reported. To fill this gap, the detailed investigation of the formation of silver/hematite nanoparticle bilayers at the surface of polystyrene microparticles is reported. First, the hematite/polystyrene raspberry-like microcomposites are obtained by immobilization of hematite nanoparticles under an electrostatically-driven process. The stability of hematite/polystyrene microcomposites at elevated temperatures up to 323 K is monitored using microelectrophoresis. No significant changes in the hematite nanoparticle layer coverage are observed after prolonged time of incubation. This proves the irreversible character of nanoparticle immobilization. Next, the hematite/polystyrene microcomposites are utilized as the interfaces for immobilization of negatively charged silver nanoparticles. This process is quantitatively described using electrokinetic measurements. The changes in the hydrodynamic diameter of microcomposites are also determined. Finally, the validity of the electrokinetic model used in this work for predicting the zeta potential of the silver/hematite/polystyrene microcomposites is confirmed.     

充气塑料柱腔的制备与保气半寿命

 研究了聚苯乙烯塑料柱腔的两种制备方法：采用聚苯乙烯溶液旋转涂层和熔体浸涂。聚苯乙烯熔融后浸涂制备的塑料柱腔存在一定的结晶取向和很多气泡,去掉铜芯轴后,塑料柱腔因缺陷太多几乎不能保气,成品率非常低,不到10％。利用聚苯乙烯溶液通过多次旋转涂层和烘干过程制备的塑料柱腔具有很低的表面粗糙度,柱腔厚度为10～30 m,表面粗糙度5～20 nm,采用0.3～0.4 μm聚酰亚胺膜封口保气,气体介质为氪气,通过X射线荧光谱仪测量柱腔保气半寿命约24 h。采用保气罐储存和运输无源塑料柱腔充气靶,打靶时腔内气体密度可保持在初始状态的92％左右。     

软X射线辐照对绝缘材料沿面闪络性能的影响

绝缘体真空沿面闪络成为制约脉冲功率技术高电压、大电流和小型化发展应用的主要因素之一。在PTS装置的真空环境中,绝缘材料在受到软X射线辐照的情况下,其绝缘性能受到很大影响。因此为了提高PTS中交联聚苯乙烯的绝缘性能,同时更深刻地认识沿面闪络的机理,通过研究软X射线对于交联聚苯乙烯的辐照作用,观测到了不同辐照次数对于沿面闪络性能的影响。实验表明:未受到辐照的样品其真空沿面闪络性能高于软X射线辐照过的样品,而受14次钨丝阵辐照的样品其真空沿面闪络性能略高于受2次铝丝阵辐照的样品。同时,从软X射线对于绝缘体表面的辐照机理很好地解释了这种实验现象。