铁电纳米材料的制备、性能和应用前景

对近年来有关铁电纳米粉体、纳米复合材料、以及纳米陶瓷的制备,结构和性能进行了介绍.对由于粒子尺寸减小引起的结构和性能的改变及其相关机理进行了讨论.透明铁电纳米复合材料可望在光学存储、光学计算等光学器件中得到应用.而纳米陶瓷由于介电特性、耐电压、抗老化、机械强度等性能的提高,因而可以广泛用于改进现有电容器材料的性能,获得性能更加优良的器件.     

纳米颗粒-介电复合材料三阶光学非线性的研究进展

纳米颗粒-介电复合材料显示出优良的三阶非线性光学性能,是应用于未来全光器件的理想材料.其中,纳米颗粒的尺寸、浓度、组成和结构,基体的选择,测试方法中选用的激光波长和脉冲宽度等多种因素都对此类复合材料的三阶非线性光学性能有很大的影响,了解这些影响因素对材料的制备和应用具有重要的指导意义.在此基础上,研究指出核壳结构纳米颗粒-介电复合材料具有更加优异的三阶非线性光学性能,是目前的研究热点.     

碳纳米管和金属纳米粒子的异质连接研究进展

碳纳米管作为金属纳米粒子的载体材料,用于催化荆、纳米电子学、光学、纳米生物技术等领域.但碳纳米管与金属之间表面张力的差异显著,不利于金属纳米粒子附着.通过碳纳米管表面改性,利用功能基团可实现较好的异质连接.分析了碳纳米管与金属纳米粒子之间的异质连接及其在功能材料中的应用研究状况,探讨了解决碳纳米管/金属复合材料界面结合问题的各种方法,展望了异质连接技术的发展趋势.     

纳米金属颗粒的湿化学制备

纳米金属颗粒在光电子、磁性材料和器件上具有表面增强Raman效应,量子点效应和高密度存储等重要特性.综述了在光电子、磁性材料和器件有着应用前景的金、银、铜、钴、镍、铋等金属纳米颗粒的湿化学制备,探讨了金属纳米颗粒湿化学制备控制颗粒大小、形状的一些因素和一般性特点,为制备颗粒大小、形状可控的其它种类的金属纳米颗粒作参考.     

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     

金属纳米粒子的量子等离子体共振效应研究取得突破

具有纳米尺度的金属纳米粒子在物理、力学等性能方面迥异于块体金属材料,其中以纳米金属粒子的量子等离子体共振效应在纳米光学、生物学、传感器、光谱仪及太阳能的收集等领域具有巨大的潜在应用价值,相关研究一直备受国内外科研人员的关注。在纳米金属粒子的量子等离子体共振效应中,人们以往的研究对象多为     

纳米微粒的表面修饰与聚合物杂化光学材料的高性能化

高折射率材料在很多光学仪器、光电器件以及信息储存和传导等领域均具有广泛的实际应用价值,备受科研工作者们的关注。但是由于传统光学树脂折射率可调范围小,一般低于1.80,使其逐渐不能满足当代社会对器件微型化的要求。笔者研究组近十年来,通过将具有高折射率的无机纳米微粒引入到传统光学树脂材料,得到了一系列基于不同高折射率纳米微粒的高性能聚合物光学杂化材料,并取得了突破性的进展,所得杂化材料的折射率最高可以达到2.3以上。为了方便广大的科研同行对这类高性能聚合物杂化材料的深入研究以及便于这类材料实现实际的应用价值,笔者基于研究组近十年来的研究成果,从纳米微粒的表面修饰方法和该研究领域的相关应用方面对这类高性能聚合物杂化材料做一个比较系统的介绍。     

纳米复合镶嵌薄膜

阐述了镶嵌纳米复合薄膜的发展、制备、评估及物件。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、恒温系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膜等近年来的实验结果。     

多枝CdS纳米晶粒的溶剂热法制备及光学性能研究

本文以溶剂热法在乙二醇溶剂里制备了小尺寸的多枝权CdS纳米晶粒,通过溶剂、硫源的选择,使其直径接近激子的玻尔半径(6nm),分析硫源和溶剂对CdS粒子晶体结构、形貌和尺寸的控制作用.对多枝权粒子的形成机理进行探讨,初步得到一种可能的两相共存的生长机制.光学性能的测试显示样品具有良好的量子尺寸效应和发光性能.选择合适的反应源和溶剂可调整半导体纳米粒子的形貌和尺寸,对制备满足不同应用需要的纳米结构,尤其是复杂形貌的纳米量子器件的应用具有重要的意义.     

木质素基金属纳米粒子复合材料的制备及其应用研究进展

木质素是一种最丰富的芳香族天然高分子生物质资源,木质素纳米粒子既具有木质素原本特点,还具有纳米材料的纳米效应等特性,在众多功能材料领域具有很大的潜在应用价值,特别是作为绿色还原剂直接还原金属离子生成木质素基金属纳米粒子复合材料,被广泛应用于催化领域等。本文综述了木质素纳米粒子的制备及其在金属离子还原和金属纳米粒子负载的研究进展,重点综述了木质素基金属纳米粒子复合材料在不同应用领域的研究进展,最后总结并展望了木质素在金属纳米粒子复合材料制备和应用中面临的机遇和挑战。      

Optoelectronic and nonlinear optical processes in low dimensional semiconductors

Spatial confinement of quantum excitations on their characteristic wavelength scale in low dimensional materials offers unique possibilities to engineer the electronic structure and thereby control their physical properties by way of simple manipulation of geometrical parameters. This has led to an overwhelming interest in quasi-zero dimensional semiconductors or quantum dots as tunable materials for multitude of exciting applications in optoelectronic and nonlinear optical devices and quantum information processing. Large nonlinear optical response and high luminescence quantum yield expected in these systems is a consequence of huge enhancement of transition probabilities ensuing from quantum confinement. High quantum efficiency of photoluminescence, however, is not usually realized in the case of bare semiconductor nanoparticles owing to the presence of surface states. In this talk, I will focus on the role of quantum confinement and surface states in ascertaining nonlinear optical and optoelectronic properties of II–VI semiconductor quantum dots and their nanocomposites. I will also discuss the influence of nonlinear optical processes on their optoelectronic characteristics.     

电沉积纳米复合材料的研究与应用

纳米复合材料电沉积工艺是在金属电沉积过程中加入纳米颗拉,使其与金属共沉积,并通过控制适当的工艺条件,最终获得具有优良性能的纳米复合材料的过程。分析了电沉积过程中纳米复合材料的形成机理,综述了各种因素对复合电沉积过程的影响,介绍了复合沉积层的各种性能及应用。     

Advancement of Ag–Graphene Based Nanocomposites: An Overview of Synthesis and Its Applications

Graphene has been employed as an excellent support for metal nanomaterials because of its unique structural and physicochemical properties. Silver nanoparticles (AgNPs) with exceptional properties have received considerable attention in various fields; however, particle aggregation limits its application. Therefore, the combination of AgNPs and graphene based nanocomposites (Ag–graphene based nanocomposites) has been widely explored to improve their properties and applications. Excitingly, enhanced antimicrobial, catalytic, and surface enhanced Raman scattering properties are obtained after their combination. In order to have a comprehensive knowledge of these nanocomposites, this Review highlights the chemical and biological synthesis of Ag–graphene nanocomposites. In particular, their applications as antimicrobial agents, catalysts, and sensors in biomedicine, agricultural protection, and environmental remediation and detection are covered. Meanwhile, the factors that influence the synthesis and applications are also briefly discussed. Furthermore, several important issues on the challenges and new directions are also provided for further development of these nanocomposites.     

ZnO@Porous Media, Their PL and Laser Effect

Optoelectronic nanocomposites are a new class of materials, which exhibit very interesting and particular properties and attract a growing attention due to their potential applications in information storage and optoelectronic devices. Zinc oxide, ZnO, is one of the most interesting binary semiconductor （3.37 eV） with very important optical properties, which can be used in the fields such as short wavelength lasers, blue light emitting diodes, UV detectors, gas sensors, etc. This paper reviews the very recent progress in the prepa- ration of silica-based ZnO nanocomposites. After an introduction reviewing the theoretical background, the article will begin with a survey of the optical properties and the quantum size effect （QSE） of ZnO/SiO2 nanocomposites prepared by the inclusion of ZnO nanoclusters inside silica mesoporous materials. The second part will focus on one of the most interesting properties of ZnO/SiO2 nanocomposites, which is the random lasing effect after one- and two-photon excitation. The final part will deal with the introduction of ZnO nanoparticles inside microporous zeolites and the observation of QSE. For comparison, the photoluminescence （PL） and QSE properties of ZnS nanoparticles occluded in mesoporous media are also described. New potential applications will be discussed since short-wavelength devices are required by industry to design, for instance, new information storage supports and biolabelling devices.     

Preparation and characterization of P(VDF-TrFE)/Al2O3 nanocomposite

Hybrid nanocomposites based on crystalline nanoparticles dispersed in polymer matrix have been widely studied in the past few years because of the ability of these materials to combine the properties of organic polymer and inorganic nanoparticles. The aim of this work is to tune the mechanical properties of a piezoelectric polymer by adding nanoparticles to the matrix. In this paper, alumina nanoparticles were dispersed in the copolymer P(VDF-TrFE), which exhibits high piezoelectric coefficient after polarization under high electric field without needing stretching during the polarization process. Transmission electron microscopy and scanning electron microscopy demonstrate the high rate of welldispersed nanoparticles with 10% of alumina nanoparticles added to the matrix. Piezoelectric measurements indicate that P(VDF-TrFE) may be filled by up to 10 wt% of alumina while retaining its high piezoelectric properties and increasing its elastic constant by more than 20%, measured by Brillouin spectroscopy. This work opens a wide range of applications using nanoparticles with nonlinear optical, pyroelectric, magnetic, or ferroelectric properties.     

功能性聚合物基纳米复合材料

对聚合物基纳米复合材料研究现状进行了概述，并就其在电、磁、发光性能以及光催化等方面的国内外研究进展进行了全面综述。     

Band gap tuning and nonlinear optical characterization of TiO2–SiO2 nanocomposites with respect to composition and phase

We report on the linear and nonlinear optical studies on TiO₂–SiO₂ nanocomposites with varying percentage ratio. It is found that optical band gap of the material varies with respect to the amount of the SiO₂ in the composite. Nonlinear optical characterization of these samples was studied by using open as well as closed aperture Z-scan technique using an Nd:YAG laser (532 nm, 7 ns, 10 Hz). The nanocomposites showed enhanced nonlinear optical properties than pure TiO₂ and this can be attributed to the surface states and weak dielectric confinement of TiO₂ nanoparticles by SiO₂ matrix. The nanocomposites were thermally treated and similar studies were performed. The anatase form of TiO₂ in the nanocomposites showed superior properties relative to the amorphous and rutile phase of the composite. The involved mechanism is explained by taking into account the dominant role played by the excitons in the TiO₂ nanoparticles.     

Hybrid composite material based on polythiophene derivative nanofibers modified with gold nanoparticles for optoelectronics applications

Conjugated polymers have been extensively applied as active materials in nanostructured platforms for optical and electrical devices. The incorporation of metal nanoparticles (NPs) into the polymer-based platform arises as a strategy to develop novel hybrid functional nanocomposites with enhanced electrical and optical properties. However, efficient and simple processing routes to produce such nanocomposites are still on demand. In this work, we present an effective route to obtain functional nanocomposites based on electrospun nanofibers coated with gold nanoparticles, displaying interesting optical and electrical properties. Polymethyl methacrylate (PMMA) electrospun nanofibers doped with poly(3-hexyl thiophene-2,5-diyl) (P3HT) were obtained by the electrospinning technique, and displayed a strong red emission centered at 650 nm assigned to P3HT. Such nanofibers were deposited on to fluorine-doped tin oxide electrodes and with modified with gold nanoparticles (AuNPs) in order to produce hybrid composite materials. The performance of electrodes modified with PMMA/P3HT-AuNPs composite material was evaluated by impedance spectroscopy and revealed an enhancement of electron transfer kinetics, which indicates it as a potential platform for optical and electrochemical (bio)sensors.     

Novel Nanoparticle‐Reinforced Metal Matrix Composites with Enhanced Mechanical Properties

This paper summarizes and reviews the state‐of‐the‐art processing methods, structures and mechanical properties of the metal matrix composites reinforced with ceramic nanoparticles. The metal matrices of nanocomposites involved include aluminum and magnesium. The processing approaches for nanocomposites can be classified into ex‐situ and in‐situ synthesis routes. The ex‐situ ceramic nanoparticles are prone to cluster during composite processing and the properties of materials are lower than the theoretical values. Despite the fact of clustering, ex‐situ nanocomposites reinforced with very low loading levels of nanoparticles exhibit higher yield strength and creep resistance than their microcomposite counterparts filled with much higher particulate content. Better dispersion of ceramic nanoparticles in metal matrix can be achieved by using appropriate processing techniques. Consequently, improvements in both the mechanical strength and ductility can be obtained readily in aluminum or magnesium by adding ceramic nanoparticles. Similar beneficial enhancements in mechanical properties are observed for the nanocomposites reinforced with in‐situ nanoparticles.     

Enhanced Ultrafast Nonlinear Optical Response in Ferrite Core/Shell Nanostructures with Excellent Optical Limiting Performance

Nonlinear optical nanostructured materials are gaining increased interest as optical limiters for various applications, although many of them suffer from reduced efficiencies at high‐light fluences due to photoinduced deterioration. The nonlinear optical properties of ferrite core/shell nanoparticles showing their robustness for ultrafast optical limiting applications are reported. At 100 fs ultrashort laser pulses the effective two‐photon absorption (2PA) coefficient shows a nonmonotonic dependence on the shell thickness, with a maximum value obtained for thin shells. In view of the local electric field confinement, this indicates that core/shell is an advantageous morphology to improve the nonlinear optical parameters, exhibiting excellent optical limiting performance with effective 2PA coefficients in the range of 10^?12 cm W^?1 (100 fs excitation), and optical limiting threshold fluences in the range of 1.7 J cm^?2. These values are comparable to or better than most of the recently reported optical limiting materials. The quality of the open aperture Z‐scan data recorded from repeat measurements at intensities as high as 35 TW cm^?2, indicates their considerably high optical damage thresholds in a toluene dispersion, ensuring their robustness in practical applications. Thus, the high photostability combined with the remarkable nonlinear optical properties makes these nanoparticles excellent candidates for ultrafast optical limiting applications.