ELECTRICAL AND MECHANICAL PROPERTIES OF POLYANILINE FILMS——EFFECT OF NEUTRAL SALTS ADDED DURING POLYMERIZATION*

The electrical and mechanical properties of polyaniline (PANI) films syn-thesized by the presence of the selected neutral salts in the polymerization were measuredas a function of the properties and the concentration of the selected neutral salts, andthe protonation state. It was found that both the electrical and mechanical properties ofPANI films were enhanced by adding neutral salts in the polymerization. The adding ofthe neutral salts in the polymerization resulted in extended conformation of polymer chainand increasing of molecular weight of PANI, which may be the reasons why the electricaland mechanical properties of PANI films were improved by the presence of neutral salts inthe polymerization.     

穿过液膜的自发电势振荡

本文研究的体系是在一个U 形玻璃管里,底部加入苦氨酸的硝基苯溶液(油相)作为人造液膜,右边支管中加入含乙醇的十八烷基三甲基氯化铵的水溶液,左边支管中加入蔗糖水溶液(或去离子水).电势振荡振幅在20—150mV 之间.根据文献报导,表面活性剂穿过油相产生界面振荡.本实验用的十八烷基三甲基氯化铵(简称C_(18)~+Cl~-)是一个阳离子型表面活性剂,与苦氨酸(简称HA)接触时显橙红色,     

Structural study and physical properties of a new phosphate KCuFe(PO4)2

Single crystals of a new phosphate KCuFe(PO₄)₂ have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P2₁/n and its parameters are: a=7.958(3) Å, b=9.931(2) Å, c=9.039(2) Å, β=115.59(3)° and Z=4. Its structure consists of FeO₆ octahedra sharing corners with Cu₂O₈ units of edge-sharing CuO₅ polyhedra to form undulating chains extending infinitely along the b-axis. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the K⁺ ions are located. The Mössbauer spectroscopy results confirm the exclusive presence of octahedral Fe³⁺ ions. The magnetic measurements show the compound to be antiferromagnetic with C_m=5.71 emu K/mol and θ=−156.5 K. The derived experimental effective moment μ_ex=6.76μ_B is somewhat higher than the theoretical one of μ_th=6.16μ_B, calculated taking only into account the spin contribution for Fe³⁺ and Cu²⁺ cations. Electrical measurements allow us to obtain the activation energy (1.22 eV) and the conductivity measurements suggest that the charge carriers through the structure are the potassium cations.     

强度调制光电流谱研究TiO2悬浮体系光催化机理

用强度调制光电流谱在光电化学电池中研究TiO2粒子悬浮液体系中的光催化反应机理,将强度按正弦变化的调制光照射TiO2粒子悬浮液,产生随频率变化的光电流响应,收集在Pt电极上,得到了光电流响应复数平面图,其上半圆和下半圆分别代表光生空穴和光生电子的阴极还原和阳极氧化反应过程.根据阴极和阳极光电流的幅度及上下半圆的特征频率分析讨论了光催化反应的机理及外加电压和H2O2添加物的影响.     

一类新型杂环聚芳酰胺的合成与性能研究

采用二氮杂萘类双酚 4 (4 羟基苯基 ) 2 ,3 二氮杂萘 1 酮 (DHPZ)与对氯苯腈反应制得二腈化合物 ,进一步水解为二酸 .以此新型二酸与不同二胺聚合制得的聚芳酰胺均具有较高的耐热性能 ,其Tg 在 2 91～318℃ ,且易溶于极性非质子溶剂中 .聚合物的特性粘数为 1 17～ 1 5 0dL g(2 5℃ ,0 5 %inNMP) ,对所得聚酰胺进行性能研究 ,其拉伸强度为 71～ 86MPa ,断裂伸长率为 8%～ 13% ,拉伸模量为 0 86～ 1 0 2GPa ,电阻系数数量级为 10 1 4～ 10     

Co掺杂对YBa2 Cu3 O7-δ电阻率与塞贝克系数的影响

用固态反应法制备了YBa2Cu3-xCoxO7-δ(x=0.0,0.1,0.2,0.5)样品,研究了Co掺杂对YBa2Cu3O7-δ高温区的电阻率和塞贝克系数的影响。随着Co含量的增加,样品的电阻率和塞贝克系数逐渐增大,从金属性导电转变为p型半导体导电。x=0.2和0.5样品的电导活化能在500K处发生突变,高温区的活化能大于低温区的活化能。通过塞贝克系数与温度的关系,计算出x=0.2和0.5样品的费米能级分别为0.02和0.12 eV。当温度高于650-700K时,氧脱附显著影响样品的电输运性质,导致电阻率和塞贝克系数随温度增加而增大。     

Synthesis of aqueous dispersion of graphenes via reduction of graphite oxide in the solution of conductive polymer

Graphene sheets were produced by chemical reduction of graphite oxides in the solution of ionic conductive polymer, Nafion. The obtained graphene, coated with Nafion, can be re-dispersed in water, and readily forms stable dispersed state. The polymer-coated graphene had been characterized by FT-IR spectroscopy, UV-vis and X-ray photoelectron spectroscopy (XPS). The PEDOT film with Nafion-coated graphene increased significantly from 0.25 S/cm for pure PEDOT film and reached 12 S/cm. Further, the films of PEDOT doped Nafion-coated graphene had also higher conductivities compared to films doped PSS-coated graphene.     

Development of superconducting power devices in Europe

Europe celebrated last year (2008) the 100-year anniversary of the first liquefaction of helium by H. Kammerling Onnes in Leiden. It led to the discovery of superconductivity in 1911. Europe is still active in the development of superconducting (SC) devices. The discovery of high critical temperature materials in 1986, again in Europe, has opened a lot of opportunities for SC devices by broking the 4 K cryogenic bottleneck.     

From micro-to nanosized particles:Selected characterization methods and measurable parameters

Airborne microand nanoparticles-aerosols-play an important role in many natural phenomena and in a variety of industrial processes,as well as the public health issue. They may be of natural or anthropogenic origin;their presence in an environment might be intentional or due to undesirable release. In any case,merely the particle detection and characterization,ideally in real-time,provide an insight into the potential burden allowing also controlling and abatement measures. Due to the broad size range it is ...     

Local electronic and electrical properties of functionalized graphene nano flakes

Based on experimental findings models of amorphous graphene related carbon materials were generated using graphene nano flakes. On the optimized structures detailed local electronic properties were investigated using density functional theory. The electrical conductivities of all these models were also estimated using an in-house program based on tight-binding method. The calculated electrical conductivity values of all the models agreed well with the trend of calculated energy gap and graphitic character.