Heterogeneous Nanoassembling: Microfluidically Prepared Poly(methyl methacrylate) Nanoparticles on Ag Microrods and ZnO Microflowers

The heterogeneous assembly of colloidal polymer particles on the nano‐ and microstructures of a metal is a versatile platform for adjusting the mechanical and electrical properties simultaneously. The assemblies of silver (Ag) microrods and flower‐like zinc oxide (ZnO) microparticles with poly(methyl methacrylate) (PMMA) nanospheres are presented to prepare advanced composite materials. PMMA nanoparticles are prepared via the emulsion polymerization technique using a microfluidic preparation step in the presence of cationic surfactant. The surface charge of PMMA particles determines the binding interaction strength with inorganic constituents. Ag microrods and ZnO microparticles are prepared in a batch and in a continuous flow process, respectively. The assembling process can be explained by a particle–particle binding process due to the electrostatic interaction for both types of nanoassemblies. The observed binding pattern reveals certain lateral mobility of the small polymer particles at the surface of larger metal particle. The particle ratios in the nanoassemblies can be tuned over a wide range by changing the reaction parameters.     

Development of high-performance aluminium 6061/SiC nanocomposites by ultrasonic aided rheo-squeeze casting method

In the modern era, the need for new products with novel processing and multipurpose materials is increased. The current market requirements for engineering applications are lightweight, high strength and low-cost materials. This paper explores the novel development process of high-performance nano cermet material for aerospace applications. Herein, lightweight aluminium 6061 + 2% of SiC (40 nm) nano cermet was fabricated through the casting method. The effects of ultrasonication, double stir casting or rheocasting, and squeezing pressure on nano cermet fabrication were successfully investigated by comparing their physical, thermal and mechanical properties. Scanning electron microscopy was employed to analyse the morphology of the cermets, and the presence of reinforcements was verified through EDS. The reinforcement of SiC into Al 6061 improved density, hardness, and reduction in porosity and grain refinement. This study reveals a novel fabrication process of ultrasonic-aided rheo-squeeze casting technique which enhanced the mechanical properties of the cermets compared to Al 6061 alloy due to nanoparticles homogeneous distribution, nominal agglomeration and porosity.     

太赫兹波段表面等离子光子学研究进展

表面等离子光子学是研究金属、 半导体纳米结构材料独特的光学特性, 是目前光子学中最有吸引力、 发展最快的领域之一. 伴随着微/纳制造技术与计算机模拟技术的进步, 表面等离子光子学在可见光、 红外、 太赫兹以及微波频域得到了广泛研究, 在高灵敏生化传感、 亚波长光波导、 近场光学显微、 纳米光刻等领域有潜在的应用价值. 特别是人工超材料的发展, 为自然界长期缺乏响应太赫兹波的材料和器件奠定了基础, 从而也促进了太赫兹波段表面等离子光子学的研究. 本文从太赫兹表面等离子波的激发、 传导、 最新应用及未来发展趋势等几个方面进行了回顾和讨论, 将最新研究成果展示给读者.     

半导体纳米材料非线性光学性质的研究进展

半导体纳米材料由于具有重要的理论研究意义和潜在的巨大应用前景而成为当今理论和材料研究的特点，该文综述了半导体纳米材料非线性光学性质的研究进展。     

微波吸收法研究ZnO光电子衰减过程

微波吸收无接触测量技术可以用于半导体粉体材料、微晶材料等研究光生载流子衰减过程。本文采用微波吸收法在室温下分别测量了ZnO纳米材料和微晶材料的光电子衰减过程。发现在紫外激光短脉冲激发下,两种材料的导带光电子寿命有很大的差异,ZnO微晶粉体材料的光电子寿命为50ns,而ZnO纳米材料的光电子寿命仅为10ns。分析认为纳米ZnO的光电子寿命缩短是由于纳米ZnO晶体的表面积远远大于体材料的表面积,纳米材料的表面形成了大量的缺陷能级,加速了光电子的表面复合,缩短了光电子的寿命。纳米材料内部缺陷增多和量子限域效应同样会缩短光电子的寿命。     

Fabrication of 3D microfluidic structures inside glass by femtosecond laser micromachining

Femtosecond lasers have opened up new avenues in materials processing due to their unique characteristics of ultrashort pulse widths and extremely high peak intensities. One of the most important features of femtosecond laser processing is that a femtosecond laser beam can induce strong absorption in even transparent materials due to nonlinear multiphoton absorption. This makes it possible to directly create three-dimensional (3D) microfluidic structures in glass that are of great use for fabrication of biochips. For fabrication of the 3D microfluidic structures, two technical approaches are being attempted. One of them employs femtosecond laser-induced internal modification of glass followed by wet chemical etching using an acid solution (Femtosecond laser-assisted wet chemical etching), while the other one performs femtosecond laser 3D ablation of the glass in distilled water (liquid-assisted femtosecond laser drilling). This paper provides a review on these two techniques for fabrication of 3D micro and nanofluidic structures in glass based on our development and experimental results.     

半导体材料基因组计划:硅基发光材料

材料基因组计划旨在通过实验、计算和理论的有机整合协同创新, 实现新材料研发周期减半, 成本降低到现有的几分之一, 以期加速在清洁能源、国家安全、人类福利等方面的进步. 半导体材料的研究和发展奠定了半导体科学技术在当前人类社会发展中至关重要的地位, 半导体材料基因组计划的实施将促使半导体科学技术的研究和应用进入一个崭新的时代. 本文基于基因遗传算法理论设计硅基发光材料的研究工作探讨了半导体材料基因组计划的实施构想. 首先简单介绍了硅基发光的应用前景和开发硅基发光材料所面临的挑战. 随后介绍了基于模拟达尔文物种进化的基因遗传算法和高精度高性能的能带结构计算方法, 设定高效带边发光这一目标, 逆向设计拥有直接带隙发光的二维Si/Ge超晶格和一维Si/Ge核-多壳纳米线, 为实施半导体材料基因组计划提供了一个范例, 显示了材料基因组计划的强大力量和巨大价值. 最后对半导体材料基因组计划的实施提了几点建议.     

Five-Level Structural Hierarchy: Microfluidically Supported Synthesis of Core–Shell Microparticles Containing Nested Set of Dispersed Metal and Polymer Micro and Nanoparticles

This study presents the development of a hierarchical design concept for the synthesis of multi-scale polymer particles with up to five levels of organization. The synthesis of core–shell microparticles containing nested sets of dispersed metal and polymer micro- and nanoparticles is achieved through in situ photopolymerization using a double co-axial capillaries microfluidic device. The flow rates of the carrier, shell, and core phases are optimized to control particle size and result in stable core–shell particles with well-dispersed three-level composites in the shell matrix. The robustness and reversibility of these core–shell particles are demonstrated through five cycles of drying and re-swelling, showing that the size and structure of core–shell particles remain unchanged. Additionally, the permeability and mobility of dye molecules within the shell matrix are tested and showed that different molecular weight dyes have different penetration times. This study highlights the potential of microfluidics as a powerful tool for the controlled and precise synthesis of complex structured materials and demonstrates the versatility and potential of these core–shell particles for sensing applications as particle-based surface-enhanced Raman scattering (SERS).     

Plasma-aided manufacturing

The present and potential applications of plasma-aided manufacturing are discussed and described. Plasma-aided manufacturing is used for producing new materials with unusual and superior properties, for developing new chemical compounds and processes, for machining, and for altering and refining materials and surfaces. Plasma-aided manufacturing has direct applications to semiconductor fabrication, materials synthesis, welding, lighting, polymers, anticorrosion coatings, machine tools, metallurgy, electrical and electronics devices, hazardous waste removal, high-performance ceramics, and many other items in both the high-technology and the more traditional industries in the United States     

Application of reactor neutrons to the investigation of the radiation resistance of semiconductor materials of Group III–V and sensors

The investigation of the radiation resistance of Group III–V semiconductor materials is an important and urgent problem. Magnetic sensors based on radiation resistant semiconductor materials are widely used in magnetomeasuring systems of thermonuclear industrial and experimental reactors. The basic approaches to the study of semiconductor materials under conditions of neutron irradiation and the results of some experiments on testing indium-containing semiconductor materials InSb, InAs, and their alloys InAs _x Sb_{1 ? x} are presented. The presented experience of the development of equipment for on-line testing of materials and magnetic diagnostic sensors under radiation conditions can be used for testing a wide range of materials under conditions close to those of the ITER and other thermonuclear reactors.     

用于下一代传感和光源的新型材料、光纤及器件

制造技术与复杂模型、设计工具的进步使微纳结构光学器件的实现成为可能。微纳结构光学器件可用于导光与光的相互作用,液态或气态新型光源和传感器件。IPAS致力于新型光学材料研究与开发,将玻璃工艺和光纤开发有机结合,重点研究微纳结构光纤,光纤表面功能处理和器件开发。介绍了IPAS的研究实力和近年的发展概况,其中包括中红外光学材料、纳米粒子嵌入玻璃材料、新型化学和生物传感器(适用于超低量样本及/或体内样本)、激光器件,以及用于光数据处理的新型高非线性光纤。     

ZnO一维纳米线及其异质结构的外延生长

一维纳米结构因其优异的光、电特性，在纳米电子学，光电子学器件等方面有重要的应用价值而倍受关注．在一维半导体纳米材料中，ZnO因激子束缚能大（60meV），可在室温获得高效的紫外发光而成为近年来继GaN材料后的又一研究热点．外延生长一维纳米结构ZnO及其量子阱材料除因量子尺寸效应更适宜做室温紫外发光、激光材料与器件外，还因界面和量子限制效应而具有许多新奇的光、电、和力学特性，可应用于纳米光电子学器件，传感器及存储器件，纳米尺度共振隧道结型器件和场效应晶体管的研制和开发．文章着重介绍了目前ZnO一维纳米结构制备，一维ZnO纳米异质结构和一维ZnO／Zn1-xMgxO多量子阱结构的外延生长和研究进展．     

Embedded Nanoparticles in Schottky and Ohmic Contacts: A Review

Schottky and Ohmic contacts are essential parts of electronic and optoelectronic devices based on semiconductor materials. Controlling the contact/semiconductor interface properties is the key to obtaining a contact with an optimum performance. Contacts incorporated by nanomaterials, i.e., nano-sized particles that are embedded at the interface of contact/semiconductor, can transform the conventional approaches of contact fabrication, resulting in more reproducible, tunable and efficient electronic, and optoelectronic devices. This article is a review of theoretical and fabrication progress on the last two decades to produce contacts with embedded nanoparticles (NPs). The review covers common routes of NPs deposition on different substrates (e.g., Si, Ge, SiC, GaN, GaAs₆₇P₃₃, and InP) for nanostructured contact fabrication and the theoretical models to investigate the NPs effects on the conduction mechanism and electrical properties of devices.     

飞秒激光精密微纳加工的研究进展

飞秒激光由于其超快时间特性和超高峰值功率特性在精密微纳加工领域引起了人们广泛的重视．在与物质的相互作用中它能快速、准确地将能量作用在特定的区域内，从而可以获得极高的分辨率和加工精度。文章综述了飞秒激光精密微纳加工的最新研究进展，分别就飞秒激光烧蚀微加工和飞秒激光双光子聚合产生三维微纳结构进行了介绍，阐述了各自的物理机制．最后对飞秒激光微纳加工的研究前景做了初步探讨。     

Apatite type lanthanum silicate and composite anode half cells

Apatite type rare earth silicates are being extensively studied as electrolyte material for intermediate temperature solid oxide fuel cells (SOFC). In this paper we presents results on synthesis of Al and/or Fe-doped ATLS, the design of compatible anode materials, thermal expansion properties and co-sintering of half-cells from expansion matched materials using the advanced pulsed electric current sintering (PECS) technique. The issues related to the co-sintering of half cells have been addressed successfully by the combined use of nano powders and PECS.     

Energy band and charge-carrier engineering in skutterudite thermoelectric materials

The binary CoSb₃ skutterudite thermoelectric material has high thermal conductivity due to the covalent bond between Co and Sb, and the thermoelectric figure of merit, ZT, is very low. The thermal conductivity of CoSb₃ materials can be significantly reduced through phonon engineering, such as low-dimensional structure, the introduction of nano second phases, nanointerfaces or nanopores, which greatly improves their ZT values. The phonon engineering can optimize significantly the thermal transport properties of CoSb₃-based materials. However, the improvement of the electronic transport properties is not obvious, or even worse. Energy band and charge-carrier engineering can significantly improve the electronic transport properties of CoSb₃-based materials while optimizing the thermal transport properties. Therefore, the decoupling of thermal and electronic transport properties of CoSb₃-based materials can be realized by energy band and charge-carrier engineering. This review summarizes some methods of optimizing synergistically the electronic and thermal transport properties of CoSb₃ materials through the energy band and charge-carrier engineering strategies. Energy band engineering strategies include band convergence or resonant energy levels caused by doping/filling. The charge-carrier engineering strategy includes the optimization of carrier concentration and mobility caused by doping/filling, forming modulation doped structures or introducing nano second phase. These strategies are effective means to improve performance of thermoelectric materials and provide new research ideas of development of high-efficiency thermoelectric materials.     

Stop band tuning of three-dimensional photonic crystals through coating of semiconductor materials

Fine-tuning of stop band positioning, ranging from several nano meters to several tens of nano meters, was achieved through sequential thin layer coating of semiconductor materials onto the constituent particles of a three dimensional silica-based photonic crystal. Several semiconductor materials, including TiO₂, CdS, and ZnSe, were successfully used to achieve a controllable red-shift of the stop band position of synthetic opal. The stop band shift observed in the present work can be explained by Braggs law. The coating operation is equivalent to replacing the lower dielectric constant of the material, i.e. the air around it, with a higher dielectric constant semiconductor materials, thus increasing the effective refractive index of the structure and giving a red-shift in the stop band. PACS 42.70.Qs; 78.40.Fy; 78.40.Ha; 42.70.Nq     

Fe3O4@Ag纳米粒子的制备与表征

采用共沉淀法制备了Fe3O4纳米颗粒,并以之为原料利用晶种生长法进一步制备Fe3O4@ Ag复合纳米材料.利用紫外-可见吸收光谱和表面增强拉曼散射光谱对复合纳米材料的性能进行表征,显示Fe3O4@ Ag复合纳米材料具有良好的SERS活性.     

Capped semiconductor nanocrystals for device applications

For device purpose, our main aim is to synthesise material which is chemically and thermally stable, as well as enhancement in luminescence properties followed with matching lattice parameters. This can be achieved by precisely controlling the size of semiconductor nanocrystals which can create an opportunity for producing functional materials with new properties. Here we showed advantages of using both organic and inorganic capping agents. We reported two synthesis routes, one will lead to nanocomposites and other to Core/Shell nanostructures. Our mechanism consists of two stages: core nanoparticle formation and shell growth. Gibbs free energy of hydration of Zn+2 gives more clarity for shell growth over core rather than ion displacement from core. Colloidal films comprising of nanocrystalline CdS/ZnS were fabricated by the dip coating method. A blue shift in energy level at the nanoscale is demonstrated by optical absorption. Electron microscopy studies with an SEM and TEM show a particle size of 10 nm and diffraction patterns show a crystalline nature. Absence of lattice mismatching is one of the important parameter for device fabrication, which is confirmed by Raman spectroscopy. Overall reduction in optical absorption due to blue shift is expected to result in higher performance, especially in short-circuit currents in CdS/CdTe solar cells.     

Fabrication methods of 3D periodic metallic nano/microstructures for photonics applications

Periodic metallic nano/microstructures have received a great a deal of attention in the photonics research community over the last few decades due to their intriguing optical properties. Three‐dimensional metallic nano/microstructures such as metallic photonic crystals, metamaterials, and plasmonic devices possess unique characteristics of tailored thermal radiation, negative refraction and deep subwavelength confinement of light. In this article, the recent progress on the experimental methods for the realisation of three‐dimensional periodic metallic and thin metal film coated dielectric nano/microstructures operating from optical to mid‐infrared frequencies has been reviewed. Advancement of the state‐of‐the‐art nanofabrication methods over the last few decades have led to the development of metallic nano/microstructures of diverse geometries, high resolution features and large scale production. The recent progress in the novel fabrication methods have inspired the development of functional and exciting photonic devices based on periodic metallic nano/microstructures with various applications in photonics including communications, photovoltaics, and biophotonics.