ZnSe小团簇结构稳定性和电子性质研究

文章研究了小尺寸的(ZnSe)n团簇(n=2-16)的结构和电子性质.通过手工搭建得到团簇结构,用DMol软件包进行结构优化和能量计算,最后分析计算结果 .研究结果表明,对于n=2-4,平面环状结构的能量最低;对于n=5,非平面环状结构的能量最低;对于n=6-12,空心笼状结构的能量最低;对于n=13,核-壳笼状结构的能量最低;对于n=14-16,依旧是空心笼状结构的能量最低.通过分析(ZnSe)_n团簇(n=2-16)的电子性质,我们可以得到,(ZnSe)_9团簇、(ZnSe)_(12)团簇具有很好的稳定性.     

双层有机EL器件ITO/PPV/Alq3/Al发光稳定性的研究

制备了一组由PPV和Alq3组成的双层有机EL器件ITO/PPV/Alq3/Al;比较了两个发光层厚度不同时器件发光性能的差异.测试和分析了温度、真空度、工作电压和存放时间对器件衰减规律的影响.     

The structural and magnetic properties of barium ferrite powders prepared by the solben gel method

In this paper, M-type hexagonal barium ferrite powders are synthesized using the sol-gel method. A dried precursor heated in air is analyzed in the temperature range from 50 to 1200 ℃ using thermo-gravimetric analysis and differential scanning calorimetry. The effects of the additives and the cacinating temperature on the magnetic properties are investigated, and the results show that single-phase barium ferrite powders can be formed. After heat-treating at 950 ℃ for 4h with 3 wt% additive, the coercivity and saturation magnetization are found to be 440 Oe and 57.9 emu/g, respectively.     

忆阻器、忆容器和忆感器的Simulink建模及其特性分析

忆阻器、忆容器和忆感器均是具有记忆特性的新型非线性电路元件,也被称为记忆元件.以三种电路元件的通用数学模型为依据,从数学分析的角度,对忆阻器、忆容器和忆感器的Simulink模型进行了建立.在Simulink模型中体现了记忆元件对历史状态和系统状态变量的依赖性,正确表现出其独特的记忆特性.通过一系列仿真分析,得到了忆阻器、忆容器和忆感器的元件特性,验证了模型的有效性.此外,通过对三者在不同参数、不同激励下的电路特性分析,得到了三种记忆元件等效模型随频率和幅值变化的规律,为以后忆阻器、忆容器和忆感器基于Simulink的仿真研究和应用研究奠定基础.     

无序双层六角氮化硼量子薄膜的电子性质

基于安德森紧束缚模型,本文研究了无序双层六角氮化硼量子薄膜的电子性质. 数值计算结果表明在双层都无序掺杂的情况下,六角氮化硼量子薄膜的电子是局域的, 其表现为绝缘体性质;而对于单层掺杂(无论是氮原子还是硼原子)的双层六角氮化硼量子薄膜, 在能谱的带尾出现了持续的迁移率边.这就说明在单层掺杂的双层六角氮化硼量子薄膜中产生了 金属绝缘体转变.这一结果证实了有序-无序分区掺杂的理论模型,为理解及调控双层六角氮化硼量子薄膜 的电子性质提供了有益的理论指导.     

纳米晶复合Pr2Fe14B/α-Fe永磁材料磁性的研究

采用熔体快淬的方法制备Pr₂Fe₁₄B/α-Fe纳米晶复合永磁材料.使用振动样品磁强计(VSM)测量样品的室温磁性能.实验合金成分为(Pr_xFe_94.3-xB_5.7)_0.99Zr₁(其中x＝8.2，8.6，9.0，9.4，9.8，10.2，10.6，11.0，11.4(原子分数，%)).系统地研究了辊速及合金成分对快淬带磁性能的影响，当Pr原子分数由8. 关键词： 纳米复合永磁材料 熔体快淬 2Fe₁₄B/α-Fe')" href="#">Pr₂Fe₁₄B/α-Fe 磁性     

Effect of solvent on the construction of Co(II) coordination polymers containing a semi-rigid bis(benzimidazole) derivative: syntheses,structures, and properties

Two Co(II) coordination polymers, [CoL(npa)]·2H₂O (1) and [CoL(Hnpa)₂] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H₂npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound 1 was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting a μ₂-bridging mode and connecting two Co²⁺ cations to generate a 26-membered Co₂L₂ loop. The npa^2? link adjacent Co₂L₂ loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound 2 was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa^? adopt a μ₁-η^0?:?η¹ coordination to connect adjacent Co²⁺ cations into a 2-D polymeric layer. The μ₂-bridging L ligands connect adjacent 2-D [Co(Hnpa)]_n polymeric layers into a 3-D NaCl-like framework. The Co²⁺ cations and the L ligands in compounds 1 and 2 exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing 1 and 2 and the thermal stabilities of 1 and 2 were investigated.     

An unprecedented tetranuclear Zn(ΙΙ) complex with an unsymmetric Salen-type bisoxime ligand: synthesis,crystal structure,and spectral properties

A tetranuclear Zn(ΙΙ) complex, [Zn₄L₂(OAc)₂(CH₃OH)₂] with an unsymmetric Salen-type bisoxime (H₃L?=?6-hydroxy-4′,6′-dibromo-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol), has been synthesized and structurally characterized. There are two kinds of coordination geometry (trigonal bipyramidal and square pyramidal) in the Zn(ΙΙ) complex. The molecule has serious distortion probably from the asymmetry. The complex exhibits blue emission with the maximum emission wavelength λ _max?=?423?nm when excited with 340?nm.     

Ligational behavior of new mononucleating NOO ethyl pyruvate Schiff base towards 3d metal(II) ions: an emphasis on antiproliferative and photocleavage property

A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of a tridentate hydrazone were prepared and characterized by various spectro‐analytical techniques and magnetic moment studies. The complexes were found to be monomeric and non‐electrolytes. The copper complex is electrochemically active in the applied potential range. The compounds synthesized in the present study have shown promising antiproliferative activity when screened using the in vitro method against two human cancer cell lines: HeLa and HepG2. The Escherichia coli DNA‐binding properties of all the compounds were investigated with UV–visible absorption spectrophotometric titrations, viscosity measurements, DNA melting experiments and gel electrophoreses measurements. The compounds were demonstrated to act as DNA intercalators with appreciable DNA‐binding constant values. Copyright © 2012 John Wiley & Sons, Ltd.     

Co@Aun(n=1-8)团簇的几何结构和电子性质的理论研究

本文利用密度泛函PW91方法研究了Co@Aun(n=1-8)团簇的平衡结构、稳定性和磁矩。结构优化显示Co原子在低能异构体中趋于占据最高配位位置,基态Co@Aun(n=2-6)团簇为二维结构,Co@Au7和Co@Au8转变为三维结构。原子平均结合能、二阶能量差分及HOMO-LUMO能级间隙分析表明掺杂Co原子提高了金团簇的稳定性,改变了金团簇能级间隙的奇偶振荡性,n=5为掺杂团簇的幻数。磁矩的计算揭示Co@Aun团簇的磁性主要源于Co原子的3d轨道。