Magnetic properties of nickel filament polymer-matrix composites

The magnetic properties of polyethersulfone-matrix composites with 3-19 vol.% polycrystalline nickel filaments (0.4 (im diam) were investigated. These filaments were found to exhibit hysteresis energy loss 10800 J/m³ of nickel and coercive force 16.9 kA/m, compared to corresponding values of 4930 J/m³ and 4.7 kA/m for 2 μ.m diam polycrystalline nickel fibers, 1020 J/m³ and 0.5 kA/m for 20 μm diam polycrystalline nickel fibers, and 1280 J/m³ and 2.3 kA/m for solid polycrystalline nickel.     

Giving Direction to Motion and Surface with Ultra‐Fast Speed Using Oriented Hydrogel Fibers

Thermoresponsive hydrogel fibrous membranes showing directionally controlled movements and surface change with ultra‐fast speed are presented for the first time. They show reversible coiling, rolling, bending, and twisting deformations in different controllable directions for many cycles (at least 50 cycles tried) with inside‐out change in surfaces and shapes. Speed, reversibility, large‐scale deformations and, most importantly, control over the direction of deformation is required in order to make synthetic actuators inspired from natural materials or otherwise. A polymeric synthetic material combining all these properties is still awaited. This issue is addressed and provide a very simple system fulfilling all these requirements by combining porosity and asymmetric swelling/shrinking via orientation of hydrogel fibers at different angles in a fibrous membrane. Electrospinning is used as a tool for making membranes with fibers oriented at different angles.     

压电粉体对1-3型压电复合材料的性能影响

用粉末-溶胶挤出法制备PZT压电纤维,以排列-浇铸法制备纤维体积分数为30%的1-3型压电复合材料.以热重-差热分析(TG-DSC)和扫描电子显微镜(SEM)研究了所得纤维的加热变化情况和表面形貌.测量计算压电陶瓷片与复合材料的压电常数、介电常数、机电耦合系数及机械品质因数.结果表明,纤维中的晶粒致密度越高,复合材料的压电与介电常数越高.复合材料的径向机电耦合系数(k_p)小于压电陶瓷片,厚度机电耦合系数(k_t)和k_t/k_p都大于陶瓷片.     

在微结构光纤中实现四进制向二进制的全光转换

提出并实验了一种基于高非线性色散平坦微结构光纤的四进制光信号向二进制光信号的全光转换方案。由于自相位调制(SPM)效应,不同峰值功率的ps光脉冲经过微结构光纤传输后可获得不同展宽程度的输出频谱。基于以上原理,通过滤波可将1路10Gb/s的四进制信号转化成3路不同波长的10Gb/s二进制信号,再将3路信号进行适当的时延和衰减,最后耦合成为1路20Gb/s的二进制信号,实验获得的转换信号消光比达到3.2dB。     

布拉格光纤光传输特性研究

研究了布拉格光纤结构对光传输特性的影响。对等周期结构的径向分布、高低折射率径向包层分布和准周期径向分布等布拉格光纤结构建立了光子晶体光纤仿真软件,对光场振幅三维分布、轴向传输流分布以及径向包层数对传输特性的影响进行了计算机仿真研究,研究结果对布拉格光子晶体光纤的实际加工具有重要的参考意义。     

折射率导模高双折射光子晶体光纤的偏振特性

本文应用全矢量模型,研究一种折射率导模高双折射光子晶体光纤的特性.重点研究了该种光纤的偏振特性,包括基模场的线偏振特性,模式的双折射及偏振模色散.研究表明,由于在包层中采用两种不同尺寸的空气孔,基模中两个正交偏振模简并被打破,呈现出较高的模式双折射,模式双折射比普通的保偏光纤高至少一个量级,在波长1540nm,其拍长可达0.4067mm.改变光子晶体光纤的结构参数,将获得更高的双折射和更大的群时延差.分析结果与实验测量结果相吻合.     

一种新型的全光纤超短光脉冲压缩方案

文章提出了一种基于正常色散递减光纤（ND—DDF）、单模光纤（SMF）和非线性环镜（NOLM）组成的全光纤超短脉冲压缩方案。利用光脉冲在正常色散区的色散递减光纤（ND-DDF）中传输时,在脉冲的中心部分将带上较大线性正啁啾（和普通光纤相比）,当脉冲在SMF中传输时色散致啁啾对其进行补偿从而有一个脉冲压缩的过程,最后利用NOLM对压缩后的脉冲进行进一步的压缩和消基座处理。数值模拟的结果表明：半峰全宽为10ps、能量为74pJ的高斯脉冲经过1km的DDF、79m的SMF和20m的NOLM后,可以获得峰值功率为210W,半峰全宽为120fs且几乎无基座的超短脉冲。     

金属丝微结构光纤的研究进展

金属丝微结构光纤是指具有沿石英光纤轴向均匀分布着直径为纳米量级的金属丝的光纤。这种特殊结构的光纤具有传输光波以及表面等离子体波的特性,潜在用途十分广泛。介绍了金属丝微结构光纤的性质、制备方法及其研究进展。     

Aromatic-imide-based TADF material as emitter for efficient yellow and white organic light-emitting diodes

An aromatic-imide based TADF emitter (AI-4Cz) was designed and synthesized. The TADF emitter showed high thermal stability, good electrochemical properties, obvious AIE activity, small ΔE_ST value of 0.02 eV, and intense yellow emissions with PLQY of 76%. AI-4Cz also exhibited obvious microsecond-scale delayed fluorescence lifetime. Yellow OLED based on AI-4Cz was further fabricated, which achieved EQE_max of 16.7%. Moreover, a white OLED was fabricated through the dual emission layer strategy by using AI-4Cz and DMAC-DPS as emitting dopants, and the device obtained CIE coordinates of (0.30, 0.40), CRI value of 66, and an EQE_max of 13.6%.     

Triptycene-derived TADF enantiomers displaying circularly polarized luminescence and high-efficiency electroluminescence

A pair of novel circularly polarized thermally activated delayed fluorescence (CP-TADF) enantiomers (+)-(S,S)-CTRI-Cz and (−)-(R,R)-CTRI-Cz based on chiral triptycene scaffold were designed and synthesized. The obtained triptycene-derived enantiomers displayed obvious TADF activities with small singlet-triplet energy gap value (ΔE_ST) of 0.20 eV and characteristic microsecond delayed lifetime of 15.4 μs. Moreover, the TADF enantiomers showed mirror-image circular dichroism (CD) and circularly polarized luminescence (CPL) activities, and their luminescence dissymmetry factors (g_lum) were about ±0.9 × 10⁻³. Finally, by using the TADF enantiomers as emitters, the optimized organic light-emitting diodes (OLEDs) achieved maximum external quantum efficiency (EQE_max), current efficiency (CE_max) and power efficiency (PE_max) of 15.0%, 48.8 cd/A and 46.9 lm/W, respectively.