Transparent and flexible field emission display device based on single‐walled carbon nanotubes

A fully transparent and flexible field emission device (FED) has been demonstrated. Single‐walled carbon nanotubes (SWCNTs) coated on arylite substrate were used as electron emitters for the FED and a novel metavanadate phosphor coated on the SWCNTs/arylite film was used as transparent and flexible screen. The SWCNTs/arylite based emitters and the SWCNTs/arylite/metal‐vanadate‐based phosphor showed a transmittance value of 92.6% and 54%, respectively. The assembled device also showed satisfactory transparency and flexibility as well as producing significant current. Metavanadate phosphor is considered to be an excellent candidate due to its superior luminescence properties and easy fabrication onto transparent and flexible conductive substrate at room temperature while retaining reasonable transparency of the substrate. Thus, its transparency and flexibility will open the door to next‐generation FEDs. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

碳酸盐前驱物制备Y2O3超细粉及透明陶瓷

以Y(NO3)3和NH4HCO3为原料,通过向Y(NO3)3溶液中滴加NH4HCO3的方式制备了化学组成为Y2(CO3)3·2H2O的先驱沉淀物。研究了先驱沉淀物煅烧过程中的物相变化。先驱沉淀物1100℃煅烧4h后得到了平均粒径为60nm的无团聚Y2O3超细粉体。所得粉体不添加任何添加剂,在1700℃下真空烧结4h得到了透明Y2O3陶瓷。     

Properties of bacterial cellulose transparent film regenerated from dimethylacetamide–LiCl solution

Excellent transparent films were prepared from bacterial cellulose (BC) sheets by solubilization of its defibrillated freeze‐dried specimens in a solvent of dimethylacetamide (DMAc) containing 8.0% (w/w) lithium chloride (LiCl), and their properties were compared with those of the native BC. Fibrillar structure of the native BC disappeared after dissolution, and the film formed after dissolution also loose this structure. Occurence of structural transformation from crystalline to amorphous state was also evidenced by X‐ray diffraction, solid state cross polarization/magic angle spinning ¹³C‐NMR and attenuated total reflectance–Fourier transform infrared spectroscopic analyses. In addition, excellent 3D uniform structure of the transparent BC film was further evidenced by X‐ray micro computed tomography. Plastic‐like characteristic was enhanced by film formation after dissolving the BC specimens in the DMAc–LiCl solution as shown by changing mechanical properties, a slight decrease in tensile strength (67.2 to 59.6 MPa) and breaking stress (67.2 to 58.4 MPa) but significant increase in elongation at break from 3.4 to 10.5%, and improvement of work of fracture from 5.8 to 21.2 kJ/m². Copyright © 2016 John Wiley & Sons, Ltd.     

基于薄膜编码超表面的宽频超薄声散射体

该文提出了一种基于薄膜编码超表面的宽频超薄声散射体。利用附加质量块的薄膜和空气腔组成的薄膜结构构建了反射声波相位差接近180°的两种共振单元。将两种共振单元按照一定的顺序进行排列,可以组成深亚波长尺寸下的声学超表面。所构建的声学超表面可以产生宽频有效的散射声场。通过有限元仿真软件对多个频率的近场散射声场分布、远场声指向性和扩散系数进行了仿真计算,仿真结果显示,该散射体可以高效地散射入射声波,并且散射效果在一定的频率范围内是宽频有效的。     

Polarization‐controlled surface plasmon holography

The ability of generating arbitrary surface plasmon (SP) profiles in a controllable manner is of particular interest in designing plasmonic imaging, lithography and forcing devices. During the past decades, holography has gained enormous interest and achievements in free‐space three‐dimensional displays. Here, by applying a two‐dimensional version of holography, we experimentally demonstrate a generic method to control the SP profiles. Through controlling the orientation angles of two separated slits under circular polarization incidence, the amplitude and phase of the excited SPs can be freely manipulated, which allows direct generation of the desired SP profiles. A series of controllable SP holography schemes are theoretically and experimentally demonstrated, where the holographic SP profiles with high imaging quality can be dynamically modulated by varying the circular polarization handedness or orientation angle of linear polarization. The universality and simplicity of the proposed design strategies would offer promising opportunities for practical plasmonic applications.

     

薄膜太阳电池用改进型绒面结构MOCVD-ZnO:B透明导电薄膜研究

利用低压MOCVD技术在玻璃衬底上生长了改进型绒面结构ZnO:B薄膜。改进型ZnO:B薄膜包含两层薄膜,第一层采用传统工艺技术生长了类金字塔状晶粒,第二层借助相对低温生长技术获得了类球状晶粒。典型的双层生长技术获得的MOCVD-ZnO:B薄膜具有相对高的电子迁移率~27.6 cm2/Vs,主要归因于提高了晶界质量,减少了缺陷态。随着第二层修饰层厚度的增加,MOCVD-ZnO:B薄膜的绒度提高,而光学透过率有所下降。相比于传统工艺生长的ZnO薄膜,双层结构的MOCVD-ZnO:B薄膜应用于硅基薄膜太阳电池展现了较高的太阳电池转化效率。     

纳通道的物质传输特性及应用

近年来,随着材料科学、微纳加工技术和微纳尺度物质传输理论的发展,纳通道技术得到了越来越多的研究和关注。纳通道包括生物纳通道和人工纳通道,其孔径通常为1～100 nm。在这一尺度下,通道表面与通道内物质之间的作用概率大大增强,使得纳通道表现出许多与宏观体系不同的物质传输特性,例如通道表面电荷与通道内离子之间的静电作用产生了离子选择性,通道内电化学势的不对称分布产生了离子整流特性,物质传输过程中占据通道产生了阻塞脉冲特性等。纳通道中的这些物质传输特性在传感、分离、能源等领域具有广泛应用,例如通过对纳通道进行功能化修饰可以实现门控离子传输;利用亚纳米尺度的通道可以实现单分子传感;利用通道与传输物质之间的相互作用可以实现离子、分子、纳米粒子的分离;利用纳通道的离子选择性可以在通道内实现电荷分离,将不同形式的能量(如光、热、压力、盐差等)高效转化为电能。纳通道技术是化学、材料科学、纳米技术等多学科的交叉集合,在解决生物、环境、能源等基本问题方面具有良好的前景。该文综述了近10年来与纳通道物质传输理论以及纳通道技术应用相关的前沿研究,梳理了纳通道技术的发展过程,并对其在各个领域的应用进行了总结与展...     

Accelerated Ionic Motion in Amorphous Memristor Oxides for Nonvolatile Memories and Neuromorphic Computing

Memristive devices based on mixed ionic–electronic resistive switches have an enormous potential to replace today's transistor‐based memories and Von Neumann computing architectures thanks to their ability for nonvolatile information storage and neuromorphic computing. It still remains unclear however how ionic carriers are propagated in amorphous oxide films at high local electric fields. By using memristive model devices based on LaFeO₃ with either amorphous or epitaxial nanostructures, we engineer the structural local bonding units and increase the oxygen‐ionic diffusion coefficient by one order of magnitude for the amorphous oxide, affecting the resistive switching operation. We show that only devices based on amorphous LaFeO₃ films reveal memristive behavior due to their increased oxygen vacancy concentration. We achieved stable resistive switching with switching times down to microseconds and confirm that it is predominantly the oxygen‐ionic diffusion character and not electronic defect state changes that modulate the resistive switching device response. Ultimately, these results show that the local arrangement of structural bonding units in amorphous perovskite films at room temperature can be used to largely tune the oxygen vacancy (defect) kinetics for resistive switches (memristors) that are both theoretically challenging to predict and promising for future memory and neuromorphic computing applications.     

Overview of DWDM/ODC Project

Abstract

This article introduces the main achievements resulting from the DWDM/ODC project. The five areas of research activity within the DWDM/ODC project cover some of the main issues of design and development of dense wavelength division multiplexing systems for transparent optical networks. These issues are: performance assessment with arbitrary optical filtering; performance of signaling formats; dispersion compensation strategies for directly and externally modulated systems in presence of nonlinear transmission-induced degradation; and the impact of noise and crosstalk in the extent of transparent optical networks. All five areas of research activity have contributed significantly to a better understanding of the limitations present in dense wavelength division multiplexing systems.     

The effects of substrate temperature on ZnO-based resistive random access memory devices

Ag/ZnO/Zn/Pt structure resistive switching devices are prepared by radio frequency magnetron sputtering.The ZnO thin films are grown at room temperature and 400 C substrate temperature,respectively.By comparing the data,we find that the latter device displayed better stability in the repetitive switching cycle test,and the resistance ratio between a high resistance state and a low resistance state is correspondingly increased.After 104-s storage time measurement,this device exhibits a good retention property.Moreover,the operation voltages are very low:-0.3 V/-0.7 V(OFF state) and 0.3 V(ON state).A high-voltage forming process in the initial state is not required,and a multistep reset process is demonstrated.