二维铁电体CuCrP2S6的第一性原理研究

三维铁电体材料以其众多优良的性质在许多电子行业内起着无可替代的作用,如制作铁电存储器、高能电容器等等.但随着纳米技术的日趋成熟,磁电材料逐渐受到悬空键和量子隧穿效应等负面因素的影响.因而,二维铁电材料逐渐进入科研人员的视野,它有望克服上述难题.本文利用第一性原理密度泛函理论模拟,关注了一种典型的层状金属硫磷酸盐——Cu...     

A Novel Complex of Na（I）-Nitronyl Nitroxide [Na（NIT- 1＇-MeBzIm）3]ClO4： Synthesis and Crystal Structure

A novel complex [Na（NIT-1＇-MeBzIm）3]ClO4 （NIT-1＇-MeBzIm = 2-{2＇-[（1＇- methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been prepared and structurally characterized by elemental analysis, IR spectra and X-ray diffraction methods. The title complex crystallizes in trigonal, space group P3 and Z = 2. Crystal data： C45H57ClN12NaO10, Mr = 984.47, a = 13.9411（8）, b = 13.9411（8）, c = 14.8622（16） A, γ= 120°, V= 2501.5（3） A^3, Dc = 1.307 g/cm^3, μ（MoKα） = 0.152 mm^-1, F（000） = 1038, R = 0.0637 and wR = 0.1813 for 1957 observed reflections with I 〉 2σ（I）. X-ray analysis reveals that the Na（I） ion is six-coordinated with three NIT-1＇-MeBzlm radicals. As we know, three radicals coordinating to the Na（I） ion in the main group by a chelate way is the first example. The Na（I） ion resides in a distorted octahedron with a facial configuration. Meanwhile, the intermolecular weak interactions result in a 2-D double layer conformation where the uncoordinated perchlorate anions are inserted in the packing space and take part in the H-bond interactions, and each complex is connected with six neighboring complexes and three perchlorate anions.     

非对称领结型纳米孔阵列的光透射特性（英文）

本文利用数值模拟的方法研究了两种不同的非对称领结型纳米孔结构的光学特性。对于偏置间隙的领结型纳米孔,其基模共振与孔的周长呈线性关系。并且,不同的间隙尺寸对间隙偏置的敏感度不同。对于间隙的一边的结构发生变化的领结型纳米孔,基模共振可以通过改变单个几何参量(剩余部分的高度h2)进行线性调制。另外,研究中还观察到了类Fabry-Perot共振的共振峰分裂。我们在这项工作中提出的这两种打破领结型纳米孔的对称性的方法可以灵活地对领结型纳米孔结构的共振进行操控。     

双酚A和双酚A二缩水甘油醚振动谱的理论和实验比较分析

利用基于密度泛函理论的第一性原理计算,本文研究双酚A(BPA)和双酚A二缩水甘油醚(EDGEBA)分子的结构和振动性质,分析了两种分子红外活性和拉曼活性特征振动的频率和对称性。计算结果表明,BPA分子的拉曼散射峰基本归属于对位取代苯的骨架振动,500~1600cm-1红外强度较强;对于DGEBA分子环氧基团指纹区的特征振动频率为860,930,1123,1260cm-1,其红外光谱强度较大,可用于DGEBA类树脂固化反应过程监控;1260cm1附近的振动模,其拉曼散射强度较高,可成为拉曼光谱研究固化反应过程的特征振动。而1160cm-1附近的振动属于芳香环的特征振动,强度基本不变。     

单壁纳米管的弹性性质

基于第一性原理计算了一系列单壁碳纳米管(椅型、锯齿型)和氮化硼锯齿型纳米管的杨氏模量.用实际的数值结果显示了杨氏模量与纳米管管径之间的依赖关系.还讨论了各类纳米管卷曲形变能以及平衡基矢长度a随管型的变化. 关键词： 单壁纳米管 平衡基矢长度 杨氏模量 形变能     

黄钾铁矾固溶物的制备及拉曼光谱分析

利用水热法实验制备黄钾铁矾固溶系列样品AFe_3(SO_4)_2(OH)_6,其中A位置可以被K~+、Na~+和H_3O~+占据。此外,还制备近全钾占据的黄钾铁矾作为对比样品。对制备的黄钾铁矾群样品进行了拉曼光谱测试,黄钾铁矾的拉曼光谱分为羟基区(3000~4000cm~(-1))、硫酸根内部模式、点阵振动模三个主要部分,并对有异议的振动模的归属重新做了分析。利用拉曼光谱峰的数目以及频移,离子半径的大小、键长、键角的变化等信息,采用胡克定律分析了黄钾铁矾固溶系列A位置的离子替换作用。A位置离子的替换作用主要影响黄钾铁矾结构中OH基周围的环境,使得与羟基相关的振动模发生变化。     

Synthesis,Crystal Structure and Ferromagnetic Properties of a New Dicyanamide Bridged Dicopper(Ⅱ) Complex with IM-1′-MeBzIm-κ2 N,O Mode

A new dinuclear copper(Ⅱ) complex with imino nitroxide radicals [Cu2(NO3)2(IM-1′-MeBzIm)2(dca)2] (IM-1′-MeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimi-dazoline-1-oxyl, dca = dicyanamide anion) has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group P1, with a = 9.440(5), b = 10.124(6), c = 11.603(7), α = 102.904(7), β = 94.033(6), γ = 104.299(7)°, C34H40Cu2N16O8, Mr = 927.90, V = 1038.2(10) 3, Z = 1, Dc = 1.484 g/cm3, μ(MoKα) = 1.093 mm-1, F(000) = 478, R = 0.0609 and wR = 0.1512 for 2889 observed reflections with I > 2σ(I). X-ray analysis reveals that two Cu(Ⅱ) atoms are bridged by two dicyanamides to form a centrosymmetric Cu(Ⅱ)-Cu(Ⅱ) dinuclear entity. Every Cu(Ⅱ) ion is five-coordinated with a distorted square pyramidal coordination geometry and IM-1′-MeBzIm ligand coordinates to the metal ion with the κ2 N(1′-MeBzIm), O(IM) mode to avoid steric hindrance with the methyl group in the complex. Meanwhile, the molecules are linked by intermolecular hydrogen bonds, leading to a 1-D chain structure. Moreover, such chains are further linked by π-π stacking interactions to form a 2-D network structure. Magnetic measurement demonstrates that the intramolecular exchange couplings between Cu(Ⅱ) ion and the IM-1′-MeBzIm are ferromagnetic with J = 12.46 cm-1, where the spin Hamitonian is defined as■ = -2J12 within the complex.     

Aromatic Multicarboxylate Ligands Tuned One-and Three-dimensional Zn(Ⅱ) Coordination Polymers Based on 3-(1H-pyrazol-4-yl)-5-(pyridin-3-yl)-1,2,4-triazole

Two aromatic multicarboxylate ligands tuned Zn(Ⅱ) coordination polymers, namely, {[Zn_(0.5)(H_2L)(tp)_(0.5)(H_2O)]H_2O}_n(1) and {[Zn_2(HL)(btc)(H_2O)]H_2O}_n(2)(H_2L = 3-(1 Hpyrazol-4-yl)-5-(pyridin-3-yl)-1,2,4-triazole, H_2tp = terephthalic acid; H_3 btc = 1,3,5-benzenetricarboxylic) have been synthesized. Their structures were characterized by single-crystal X-ray diffraction analysis, elemental analyses and infrared spectra. Compound 1 possesses a one-dimensional chain structure and is finally extended into a three-dimensional supramolecular architecture though hydrogen bonding interactions. Compound 2 shows a three-dimensional framework. Meanwhile, compounds 1 and 2 exhibit luminescent emission in the solid, and can be investigated as potential luminescent materials.     

碳纳米管的结构、对称性及晶格动力学

本文介绍了单层碳纳米管的结构,对称性和晶格动力学,描述了单层碳纳米管结构的表征方式,碳纳米管的晶格振动模的对称性分类和声子色散曲线。     

以Y/Ni为催化剂制备的单壁碳纳米管的拉曼光谱研究

采用电弧放电法以Y/Ni为催化制备了单壁碳纳米管（SWNTs），对样品进行了扫描电镜、透射电镜和拉曼光谱的研究。所制备的样品中单壁碳纳米管的含量较高。对单壁碳纳米管的共振拉曼散射增强效应进行了观察，随激光波长的不同，单壁碳纳米管的拉曼光谱也随之变化，尤其是低频区径向呼吸模的变化比较明显。利用布里渊区折叠法计算了单壁碳纳米管的电子态密度曲线，根据SWNTs电子态密度尖峰之间的能量差、管子的直径和呼吸模频率建立了一个图表，并对SWNTs的呼吸模进行了归属。分析结果表明：样品中单壁碳纳米管的直径分布在0.79-1.76nm范围，金属管和半导体管均存在，并且直径在1.45nm附近的碳管居多。