纳米复合镶嵌薄膜

阐述了镶嵌纳米复合薄膜的发展、制备、评估及物性。这类薄膜含有镶嵌在介质薄膜中的纳米尺度的金属颗粒或半导体颗粒。作为基础研究，它们可用于研究量子点效应、电子－空穴限域效应、声子限域效应、巨磁阻及非线性光学性能等的研究；作为应用，它们已在光－热转换、恒温数的电阻膜等获得应用，并将在电双稳开关、光开关及光电器件中获得应用。本文主要介绍了ＧａＡｓ镶嵌薄膜，同时还介绍了巨磁阻镶嵌薄膜及电双稳薄近年来的实验结     

纳米氧化物材料的结构—性能关系的思考

功能纳米氧化物的结构和性能研究是无机功能材料研究领域的一个研究热点。一般认为纳米氧化物的性能主要由形貌,表面效应和颗粒尺寸效应所决定。目前已经有大量的文献报道介绍各种形状的纳米材料的合成,但材料的性能和大颗粒体相材料相比没有明显的差别。人们利用表面效应来研究纳米氧化物的化学活性及其在光催化环境净化和重金属离子吸附等方面的应用,或通过尺寸效应来解析纳米氧化物出现的奇特的光、电、磁等现象,但普遍忽略纳米材料发生性质改变的结构因素。事实上,纳米材料的性能是由其电子结构和表面吸附的水分子来决定的:电子结构完全依赖于材料的晶体结构和晶格尺寸,而表面吸附的水分子常常会导致光猝灭或发光性能变差的现象。我们对多种氧化物纳米材料进行系统研究,初步构筑了其结构-性能的关系。(1)纳米TiO_2表面吸附大量的水分子。高温脱水导致纳米颗粒度变大。金属纳米材料和金属氧化物材料的比热都大于大颗粒材料,文献都归结于尺寸效应。最新研究表面,扣除吸附水分子的贡献后,裸露的纳米材料TiO_2的比热在实验范围内和大颗粒的基本相同。(2)利用本征黄光作为探针研完了量子尺寸效应对高结晶度ZnO纳米棒的结构和能带结构的修饰。随着ZnO纳米棒直径的增加,...     

光电子领域中的纳米半导体材料

近年来，纳米半导体材料特别是纳米硅在光电子领域中的研究已经越来越引起人们的注意，由于纳米半导体材料的量子限域效应，尺寸效应等影响使得它们在光电转移，电子器件等方面有着优异的性能，必将在未来的微电子以及纳米电子发展中发挥令人鼓舞的作用，详细介绍了纳米半导体材料在光电子领域中的发展历史，研究情况以及存在的问题等。     

镶嵌在SiO2薄膜中的锗纳米晶粒的光致发光

采用６３０ｎｍ波长的激发光在室温下对镶嵌有锗纳米晶的ＳｉＯ２薄膜进行了光致姚研究。在室温下观察到了由于双光子吸收而导致的蓝色荧光峰。按照量子限域理论对所观察到的峰的特征进行了讨论。     

RE—TM磁光记录薄膜的磁场电效应研究

研究了磁性薄膜场电效应的测试方法，RE－TM磁光薄膜的测试样品制备、样品的磁场电效应（霍尔效应和磁阻效应）及其温度特性，实验结果表明，制备的TbFeCo薄膜的补偿点约为－38℃。     

RE－TM磁光记录薄膜的磁场电效应研究

研究了磁性薄膜磁场电效应的测试方法，ＲＥ－ＴＭ磁光薄膜的测试样品制备、样品的磁场电效应（霍尔效应和磁阻效应）及其温度特性。实验结果表明，制备的ＴｂＦｅＣＯ薄膜的补偿点约为─３８℃。     

纳米纤维素的光电子性能及器件应用综述

纳米纤维素是一种近年来发展迅猛的具有胶体活性的材料，它具有携带可控电荷基团、化学活性高、光学活性高、质量轻、价格低及环境友好等特点，正在快速占领导电材料、显示器、传感器、晶体管、射频器件、发电机、发光二极管等光电子器件及关键材料领域的重要地位。目前，纳米纤维素在光电子材料器件的应用依然存在不少挑战，且纳米纤维素的光电子性能及其器件也未见报道。诸多科学问题和技术难点包括如何从纤维素出发赋予该种光电子新材料性能（胶体颗粒维度、化学基团、亲水性）、如何满足光电子器件结构加工对材料性能的要求、如何明确材料物理化学性质与器件制备的关联机制等需要总结和讨论。本文简单介绍了具有代表性的几种纳米纤维素的制备和特性，着重介绍了纳米纤维素的光电子特性，如光学透过性、光学干涉、散射、液晶手性特性等，列举和讨论了纳米纤维素在太阳能电池基板、智能响应反射涂层、光纤等领域的应用和存在的问题。本文有助于建立纳米纤维素关于制备、微观形貌特征、胶体颗粒尺度效应、关键物化特性和光电子器件性能之间的逻辑关系，可确定构建纳米纤维素相关的新器件结构的设计准则和理论根据，还可为纳米纤维素在乳液、薄膜、模板材料、储能器、电极、纸电...     

铁系纳米粉末

将纳米尺寸的铁磁性微粉（纳米颗粒）分散于绝缘性非磁性膜内或膜表面的薄膜，作为下一代传感器和存储器材料正受到普遍关注。为获得磁特性（软磁性，硬磁性）优异的这种薄膜，就必须对于构成薄膜的磁性纳米颗粒的粒径和粒间距离以及颗粒结晶方位等加以严格控制。本文研究者选择非晶态Al2O3，作为绝缘相，获得了磁特性优良的Fe系纳米粉。     

不同炭化温度制备的C/0.5Al2O3-0.5P2O5-100SiO2凝胶玻璃的光学性质

通过醇盐不完全水解制备了含有有机基团(O—C2H5)的C/0.5Al2O3-0.5P2O5-100SiO2凝胶，在氮气中加热到300,v700。C使其中的有机基团炭化，得到镶嵌在凝胶玻璃中不同尺寸的碳纳米颗粒。利用高分辨电镜、X射线衍射和喇曼光谱研究了碳纳米颗粒的结构，发现凝胶玻璃中的碳颗粒为非晶碳纳米颗粒。测试了它们的吸收光谱，发现了由于量子限域效应引起的吸收边的移动。在532nmNd：YAG激光的激发下镶嵌有碳纳米颗粒的凝胶玻璃有一强的室温发光，发光峰在586nm左右。发光峰几乎不随碳纳米颗粒尺寸的变化而变化，这种发光产生于碳纳米颗粒的表面或碳颗粒和凝胶网络的界面。     

薄膜高频磁阻抗效应及其应用

本文介绍了Ｆｅ－Ｎｉ软磁薄膜高频磁阻抗效应及在磁传感技术中的应用，分析了讨论了获得高灵敏度磁传感的途径，磁性薄膜厚度的一般控制在４００ｎｍ以上抑制Ｎｅｅｌ壁的出现，为了提高电压输出变化灵敏度，需要沿被测场方向加向Ｏｅ的偏磁场并使高频磁场形成闭合回路，感生各向异性通过在溅射薄膜过程中加几百Ｏｅ平行于膜的直流磁场获得，与各向异性磁阻效应和巨磁阻效应相比，高频磁阻抗效应传感技术灵敏度高，无巴克豪森噪声，     

基于新型纳米复合介电材料的嵌入式微电容制备及特性

嵌入式微电容技术是一种能够使电子器件微型化,并提高其性能及可靠性的方法.研究适用于嵌入式环境的高介电材料,有着重要的意义.采用粒径为92 nm的钛酸钡（BaTiO3）颗粒作为纳米无机填充颗粒,选用聚酰亚胺（PI）作为有机基体制备新型BaTiO3/PI纳米复合薄膜,并对该薄膜的介电性能、耐压特性及温度特性进行了测试;并采用光刻、溅射、刻蚀等工艺,对BaTiO3/PI纳米复合薄膜进行图形化研究,制造嵌入式微电容器件原型,其后对该器件的介电性能进行了测试.测试结果显示,嵌入式电容器件原型的介电常数在低频下达到15以上,击穿场强达到58 MV/m以上,而刻蚀和溅射工艺对薄膜的性能影响不大.     

无机颗粒形状对高储能密度有机复合材料介电性能的影响

通过在有机基体内添加无机陶瓷颗粒形成二相复合材料是当前研究高储能密度的热点和难点,材料的静电储能特性由其内部电场分布决定。对于纯高聚物材料在均匀外电场环境中其内部电场分布均匀,但当填充无机颗粒形成复合材料时,材料局部电场会发生畸变,进而影响复合材料的介电性能。本文通过有限元方法系统研究了不同形状颗粒,包括球型、纤维状和圆片状颗粒及其空间分布的电响应特性,进而分析其对复合材料储能特性的影响。结果表明,颗粒形状及空间分布的不同均会产生不同的局部电场分布,对于球型颗粒其顶端和低端会出现明显的电场集中现象;对于纤维状颗粒,当其长径比较小时,其端部束缚电荷产生的电场畸变不能被忽略。最后,本文建立了不同形状颗粒填充复合材料三维有限元模型,计算结果表明,在相同填充浓度下,一维纤维状颗粒填充复合材料的介电常数最大,二维圆片状颗粒填充复合材料介电常数最小,而球型颗粒填充复合材料介于二者之间。本文对理解复合材料储能特性的微观机制具有重要的意义。      

辅助电场下TeO2-Nb2O5-AgCl系统玻璃的核化与析晶机理研究

在玻璃材料热处理过程中施加辅助电场,如果玻璃相的介电常数小于析出晶相的介电常数,则对玻璃的核化、晶化过程起促进作用;反之则起抑制作用．本文推导了辅助电场与温度场共同作用对玻璃核化、析晶过程的影响机理,研究了辅助电场对TeO2-Nb2O5-AgCl系统玻璃核化与析晶过程的促进作用．结果发现,辅助电场能帮助玻璃在稍低于核化和晶化温度区域的温度下成核和析晶,它可以成为控制玻璃核化和晶化过程的一个“开关”,有可能用以精确控制玻璃中纳米晶体的生长．     

The role of the surface ligand in the optical properties of CdS quantum dots in poly(vinyl alcohol) matrix

The synthesis and characterization of CdS nanoparticles prepared in poly(vinyl alcohol) (PVA) in situ, to produce a series of CdS/PVA nanocomposite films, is described in this paper. The role of 2-mercaptoethanol as the surface ligand for the nanoparticles has been investigated. Different molar concentrations of the cadmium precursor have also been evaluated, aiming at the preparation of stable aqueous colloidal systems and polymeric films. UV–visible (UV–Vis) and photoluminescence spectroscopies together with scanning electron microscopy and transmission electron microscopy have been used for characterization of the growth kinetics and the relative stability of CdS nanocrystals in the polymeric matrix. The results clearly indicate the formation of hexagonal CdS nanoparticles embedded in the PVA matrix. PVA was not effective in stabilizing colloidal CdS nanoparticles against aggregation. However, it leads to a displacement of the first optical transition of CdS due to compressive deformation effect. The combination of PVA with 2-mercaptoethanol as surface ligands had a strong effect on the optical properties of the resulting embedded CdS nanoparticles.     

The structure of reactively sputtered metal carbide and metal silicide solar selective absorbers

Transition metal carbide and metal silicide films have recently been reported to produce excellent solar selective absorbers when deposited as interference layers onto metal substrates by d.c. reactive sputtering. These films, with a graded or multilayered profile, typically have solar absorptances greater than 0.90 and thermal emittances less than 0.05. In this paper we report the results of electron diffraction and electron microprobe studies on uniform titanium carbide and titanium silicide films produced by d.c. magnetron sputtering titanium in an atmosphere of argon plus methane or silane.The films were found to be rich in the non-metallic component and to consist of small particles of a metallic titanium carbide or silicide embedded in a porous matrix of carbon or silicon. The ratio of non-metal to metal increases with the reactive gas pressure in the sputter discharge, as does the film resistivity.Films which had been annealed in vacuum for sufficient time to change their optical properties showed no observable structural changes but it is inferred that the changes in optical properties are caused by a precipitation of carbon or silicon from the metallic particles into the matrix, causing the deposits to become more dielectric.     

Use of gold island films in design of reflectors with high luminosity

We describe the optical properties of gold island films embedded between SiO2 and/or TiO2 layers. Plasmonic properties of gold films have been characterized using spectrometry and variable angle spectroscopic ellipsometry for various combinations of the embedding media. The obtained refractive indices of embedded gold island films have been used in the design of several types of multilayer reflectors.     

Structural,electrical, and magnetic properties of R-Fe-Ge (R = Y,La, Sc) films

The structural, electrical, and magnetic properties of thin R-Fe-Ge (R = Y, La, Sc) films have been studied in relation to preparation conditions (annealing temperature and the action of an external electric field on molecular vapor), film thickness, and the size of the crystallites formed in the amorphous matrix. The resistivity and coercivity of the films have been measured at temperatures from 77 to 500 K,. The results are of practical interest because the films are potentially attractive as soft-magnetic nanocrystalline materials.     

Flexible ZnO-cellulose nanocomposite for multisource energy conversion

Materials with the ability to harness multiple sources of energy from the ambient environment could lead to new types of energy-harvesting systems. It is demonstrated that nanocomposite films consisting of zinc oxide nanostructures embedded in a common paper matrix can be directly used as energy-conversion devices to transform mechanical and thermal energies to electric power. These mechanically robust and flexible devices can be fabricated over large areas and are capable of producing an output voltage and power up to 80 mV and 50 nW cm(-2) , respectively. Furthermore, it is shown that by integrating a certain number of devices (in series and parallel) the output voltage and the concomitant output power can be significantly increased. Also, the output voltage and power can be enhanced by scaling the size of the device. This multisource energy-harvesting system based on ZnO nanostructures embedded in a flexible paper matrix provides a simplified and cost-effective platform for capturing trace amounts of energy for practical applications.     

Structural and biocompatible characterization of TiC/a:C nanocomposite thin films

In this work, sputtered TiC/amorphous C thin films have been developed in order to be applied as potential barrier coating for interfering of Ti ions from pure Ti or Ti alloy implants. Our experiments were based on magnetron sputtering method, because the vacuum deposition provides great flexibility for manipulating material chemistry and structure, leading to films and coatings with special properties. The films have been deposited on silicon (001) substrates with 300 nm thick oxidized silicon sublayer at 200 °C deposition temperature as model substrate. Transmission electron microscopy has been used for structural investigations. Thin films consisted of ~ 20 nm TiC columnar crystals embedded by 5 nm thin amorphous carbon matrix. MG63 osteoblast cells have been applied for in vitro study of TiC nanocomposites. The cell culture tests give strong evidence of thin films biocompatibility.     

Electric field assisted growth of self-organized CdS films: size dependent structural and optical properties

This paper presents a systematic study of electric field assisted growth of self-organized cadmium sulphide (CdS) quantum dots (Q-CdS). CdS thin films of self-organized quantum dot like structure with different particle size have been successfully deposited simply by varying the concentration of surfactant in the reaction matrix. The model to describe the self-organization is also discussed. The size of CdS nanoparticles can be altered from 68 nm (corresponding to bulk) to 2 nm. The structural, optical, and morphological properties of Q-CdS films have been investigated. A blue shift has been observed in optical absorption and photoluminescence spectra. The strained growth of Q-CdS films has been observed. The microstructural strain calculated from peak broadening reveals an increase in strain with decreasing particle size. This study may provide a convenient method to deposit size selective and organized nanocrystalline semiconductor thin films.