苯衍生物二阶非线性光学性质的量子化学研究

本文采用引入外场微扰的CNDO/S—CI方法,计算了一系列苯衍生物的分子二阶非线性光学系数,探讨了取代基的电子性质、取代位置及取代基数目对分子二阶非线性光学系数的影响.结果表明;取代基的供电能力越强,分子的二阶非线性光学系数越大.D,A对位二取代苯和1—D,2.4—A,A三取代苯具有较高的非线性光学效应,苯衍生物中取代基数目为3时分子具有最佳的非线性光学效应.文中还对上述结论给出了初步的理论解释.     

原子核间距对平行电磁场中He2+的回归谱与闭合轨道影响的研究

利用半经典闭合轨道理论和分区自洽迭代方法计算了Rydberg态下在平行电磁场中的回归谱与闭合轨道.通过计算分子中两原子之间的距离在平衡位置、最小以及最大时的闭合轨道和回归谱讨论了分子实散射效应对平行电磁场中的回归谱与闭合轨道的影响.     

螺旋共轭分子2,2′-螺二茚-1,1′, 3,3′-四酮及其衍生物的二阶非线性光学性质与分子结构关系的研究

采用AM1和ZINDO系列方法研究了螺旋共轭分子2,2′-螺二茚-1,1′, 3,3′-四酮及其含氮衍生物的几何构型和各分子的稳定构型, 并以稳定构型为基础, 计算了这些分子的电子光谱、二阶非线性光学系数βμ, β0及电荷转移, 考察了取代基变化对βμ的影响. 计算结果表明, 所设计分子兼具较大的二阶非线性光学系数和较高的透过率, 有希望成为一类新型的二阶非线性光学材料.     

噻唑类二阶非线性光学活性分子的合成与性能

合成了4个以噻唑环为母体、含有Schiff碱结构的新型二阶非线性光学(NLO)活性分子,用红外光谱、紫外光谱、核磁共振光谱和元素分析确定了分子结构,用溶致变色法确定了二阶极化率. 分子中噻唑五元杂环和Schiff碱结构提高了NLO分子的热稳定性和透明性,噻唑的共轭芳香杂环非中心对称结构连接多个供、吸电子基团,提高了分子的二阶非线性系数. 结果表明,这些NLO分子的紫外吸收波长在350～415 nm之间,裂解温度均在300 ℃左右,二阶非线性光学系数β值达到1×10 -30 esu数量级,初步实现了"二阶非线性-透明性-热稳定性"综合性能优化的目标.     

微波频率下氯化钠溶液电导率的非线性特性

在微波频段研究了电磁场对氯化钠溶液电导率的影响. 运用不对称周期双阱势函数和Langvin方程描述了恒温条件下氯化钠溶液团簇结构中平均氢键的动力学行为, 由Bertolini公式建立团簇的平均氢键形成的概率变化与电导率变化的关系. 计算结果表明, 在恒温条件下, 当微波场的场强达到10 kV·m-1 时, 微波能会部分转化为团簇里分子间势能, 使得氯化钠溶液的电导率与电场强度有关, 这一结果与实验结果符合. 这种微波与氯化钠溶液的相互作用表现出强烈的非线性变化, 应该属于微波的非热效应范畴.     

(4,5-二氮杂-9-亚芴基)碳60中的分子轨道相互作用及其电子光谱和二阶非线性光学性质

在ZINDO方法基础上,按完全态求和(SOS)公式编制了计算分子二阶非线性光学系数β的程序.研究了(4,5-二氮杂-9-亚芴基)碳60中的分子轨道相互作用,计算了该分子的电子光谱和二阶非线性光学系数,前者与实验结果较好地吻合,后者属于理论预测性质.     

系列新推拉型多环共轭分子二阶非线性光学性质的理论研究

在AM1和ZINDO方法基础上,按完全态求和(SOS)公式编制了计算分子二阶非线性光学系数β_ijk和β_μ的程序,研究了一系列新推拉型多环共轭分子的结构、光谱和二阶非线性光学系数β(-2ω,ω,ω)和β(0,0,0).考察了分子共轭链长、分子骨架和给电子取代基对β_μ的影响,并设计了具有最大β_μ的新型非线性光学材料分子.     

一些金属超分子配合物型非线性光学材料研究进展

金属超分子配合物型非线性光学材料是一类分子基非线性光学材料,具有重要的研究价值和应用前景。本文介绍了包括偶极超分子型、八极超分子型和金属原子簇型非线性光学超分子配合物在内的该类材料国内外的研究进展,对该类材料的组装策略进行了归纳和总结。     

非线性光学有机晶体材料的研究进展

随着科技的进步和时代的发展,光电子技术将是21世纪的核心技术之一.对于光电子技术的发展,非线性光学材料,尤其是非线性光学晶体是不可缺少的关键材料.本文主要从分子设计方面概述了阴阳离子二元生色团体系、纯有机分子、纳米晶体和有机金属复合物等几种主要的非线性光学有机晶体材料的研究情况,并对其各自的特点做了简单的说明.     

含1,3-方酸苯螺旋共轭分子的设计及其电子光谱和非线性光学性质的理论研究

以量子化学半经验方法PM3优化构型为基础,利用INDO/CI方法研究了嵌入1,3-方酸的苯螺旋共轭分子的电子光谱,同时利用INDO/CI-SOS程序计算了它们的二阶非线性光学系数β_ijk和β_μ值,从而探索分子结构与电子光谱及非线性光学性质的关系.理论计算结果表明:在苯螺旋共轭分子中适当地嵌入方酸后,其二阶非线性光学系数增大.与苯螺旋共轭分子和1,3-方酸的比较表明,方酸环处于左端的体系有很好的二阶非线性光学性质,可能成为较好的光学材料.     

电磁屏蔽材料的研究进展

介绍了电磁屏蔽材料在军用和民用领域的重要性;简要阐述了电磁屏蔽的机理;综述了4种不同电磁屏蔽材料的优缺点以及研究现状,分别为金属型、表面导电型、填充复合型和本征型导电聚合物电磁屏蔽材料;分析并提出了3种提高电磁屏蔽效能的方式,分别为多孔结构设计、多层结构设计、复合填料优化.     

MXene-Based Nanocomposites for Energy Conversion and Storage Applications

Novel nanomaterials and advanced nanotechnology continuously push forward the rapid development of sustainable energy conversion and storage equipment. An emerging family of two-dimensional transition-metal carbides, nitrides and carbonitrides, also known as MXenes, have attracted increasing attention and in depth investigation. Benefitting from their unique intrinsic properties, MXenes have attracted significant attention and they have been considered as promising candidate materials for the development of environmentally friendly energy resources. A large number of studies show that MXenes have great potential in energy conversion and storage fields. Despite of their exceptional properties, MXenes also have some inherent characteristics, such as low capacities and unstable retention performances, which severely hinder their prospect applications in energy conversion and storage fields. In this Minireview, the latest progress on MXenes and their hybrid composites with small molecules, polymers, carbon or metal ions, and their applications in energy conversion and storage fields is highlighted, including their use in different types of batteries, supercapacitors, hydrogen/oxygen evolution reactions, electromagnetic interference absorption/shielding and solar steam generation. In addition, the critical challenges and further development prospects of MXene-based materials are also introduced.     

Two-dimensional electromagnetic field effects in induction plasma modelling

Based on the electromagnetic vector potential representation, a two-dimensional, axisymmetric model is proposed for the calculation of the electromageetic fields in an inductively coupled, radiofrequency (r.f.) plasma. A comparative analysis made between the flow, temperature, and electromagnetic fields obtained using this model and those given by our earlier one-dimensional electromagnetic fields model show relatively little difference between the temperature fields predicted by the two models. Significant differences are observed, however, between the corresponding flow and electromagnetic fields. The new model offers an effective means of accounting for variations in the coil geometry on the flow and temperature fields in the discharge and for achieving a better representation of the electromagnetic fields under higher frequency conditions (f>10 MHz).     

Biopolymer-Based Aerogels for Electromagnetic Wave Shielding and Absorbing

The rapid development of communication technology and electronic industry has brought unprecedented serious electromagnetic interference (EMI) and electromagnetic wave (EMW) pollution. Although EMI shields and EMW absorbers based on metal or magnetic materials were used to solve these problems, they have long been criticized for their high price, high density and easy corrosion. In order to achieve low density and efficient dissipation of electromagnetic energy, aerogels stand out among manifold materials. However, constructing aerogels with good EMI shielding or EMW absorption performance and acceptable mechanical properties is not an easy task. Burgeoning biopolymers, such as cellulose, lignin, chitin/chitosan and alginate, breathe new life into aerogels for high-efficiency EMW shielding and absorbing. Here, we reviewed the contributions of biopolymers in the fields of aerogels for EMW shielding and absorbing. At the same time, some challenges and outlook were also pointed out, aiming to promote the advance of aerogel-based EMI shields and EMW absorbers as well as the rational utilization of biopolymers.     

矿物材料在电磁屏蔽中的应用研究

为解决电磁辐射污染问题,介绍了国内外矿物材料应用在电磁屏蔽方面的研究及最新进展,尤其是在建筑混凝土、涂料以及纳米矿物材料中的应用,归纳总结了其屏蔽特点和屏蔽效果,并对发展前景作出了展望.     

A Facile Synthesis of NiFe-Layered Double Hydroxide and Mixed Metal Oxide with Excellent Microwave Absorption Properties

Microwave-absorbing materials have attracted increased research interest in recent years because of their core roles in the fields of electromagnetic (EM) pollution precaution and information security. In this paper, microwave-absorbing material NiFe-layered double hydroxide (NiFe-LDH) was synthesized by a simple co-precipitation method and calcined for the fabrication of NiFe-mixed metal oxide (NiFe-MMO). The phase structure and micromorphology of the NiFe-LDH and NiFe-MMO were analyzed, and their microwave-absorbing properties were investigated with a vector network analyzer in 2–18 GHz. Both NiFe-LDH and NiFe-MMO possessed abundant interfaces and a low dielectric constant, which were beneficial to electromagnetic wave absorption, owing to the synergistic effect of multi-relaxation and impedance matching. The optimum reflection loss (RL) of NiFe-LDH and NiFe-MMO was −58.8 dB and −64.4 dB, respectively, with the thickness of 4.0 mm in the C band. This work demonstrates that LDH-based materials have a potential application in electromagnetic wave absorption.     

Synthesis of Single‐Component Metal Oxides with Controllable Multi‐Shelled Structure and their Morphology‐Related Applications

Multi‐shelled hollow spheres metal oxides, namely materials with more than three shells, have attracted increasing attention due to their unique structure. The preparation methods of typical metal oxides including NiO, Co₃O₄ and ZnO etc. have been summarized in this review. Simultaneously, the parameters that influence the ultimate morphologies, shell number as well as the compositions have also been discussed. The potential application fields in energy conversion and storage, electromagnetic wave absorption, photocatalysis that related to the unique structure are also highlighted. Finally, the future researches of multi‐shelled hollow spheres metal oxides are further discussed.     

Design and Synthesis Strategies: 2D Materials for Electromagnetic Shielding/Absorbing

Two-dimensional (2D) materials possess special physical and chemical properties. They have been proved to have potential application advantage in the microwave absorption (MA) and electromagnetic interference (EMI) shielding. Particularly, they exhibit positive shielding and absorbing response to EMI. Here, the research progress of preparation, electromagnetic performance and microwave shielding/absorbing mechanisms of 2D composite materials are introduced. Effective preparation routes including introducing heteroatoms, constructing unique structures and 2D composite materials are described. Furthermore, the application prospects and challenges for the development of novel EMI materials are expatiated.