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1.
李蒙蒙  龙云泽  尹红星  张志明 《中国物理 B》2011,20(4):48101-048101
Cerium (Ⅲ) nitrate/poly(vinylpyrrolidone) (Ce(NO3)3/PVP) composite fibres have been prepared by electrospinning. After calcining the composite fibres in air at 500℃,CeO2 nanowires were obtained. The characterizations of the as-spun composite fibres and resultant nanowires have been carried out by a scanning electron microscope (SEM),an infrared spectrometer,an x-ray diffractometer and a fluorescence spectrophotometer. Interestingly,some unusual ribbon-like or twin fibres were observed besides the common fibres with circular or elliptic cross sections. We developed a fibre-division model resulting from Coulomb repulsion and solvent vaporization to interpret the formation of the ribbons or twin fibres,which has been confirmed by the SEM studies. Our results also indicate that the formation of the ribbons or twin fibres is less dependent on operation voltage and work distance.  相似文献   
2.
This paper reports that the multi-walled carbon nanotubes(MWCNT)/nylon-6(PA6) nanocomposites with different MWCNT loadings have been prepared by a simple melt-compounding method.The electrical,dielectric,and surface wetting properties of the CNT/PA6 composites have been studied.The temperature dependence of the con-ductivity of the CNT/PA6 composite with 10.0 wt% CNT loading(σRT-10-4 S/cm) are measured,and afterwards a charge-energy-limited tunnelling model(ln σ(T)-T-1/2) is found.With increasing CNT weight percentage from 0.0 to 10.0 wt%,the dielectric constant of the CNT/PA6 composites enhances and the dielectric loss tangent increases two orders of magnitude.In addition,water contact angles of the CNT/PA6 composites increase and the composites with CNT loading larger than 2.0 wt% even become hydrophobic.The obtained results indicate that the electrical and surface properties of the composites have been significantly enhanced by the embedded carbon nanotubes.  相似文献   
3.
An innovative heterojunction is fabricated between two sides of a freestanding thin film of HCl-doped polyaniline(PANI) derivative containing azobenzene side-chain,which is synthesized through an N-alkyl-substituted reaction.Of the film,the side with being irradiated by UV light during preparation is represented as ’A side’;the other side without being irradiated is represented as ’N side’.The electrical properties of the heterojunction are measured and the rectifying effect is observed in the current-voltage characteristic curves with the values of rectifying ratio(γ) being 20 at ±0.06 V at T = 77 K and 4 at ±0.02 V at T = 300 K separately.  相似文献   
4.
We report the current-voltage (I-V) characteristics of individual polypyrrole nanotubes and poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires in a temperature range from 300 K to 2 K. Considering the complex structures of such quasi-one-dimensional systems with an array of ordered conductive regions separated by disordered barriers, we use the extended fluctuation-induced tunneling (FIT) and thermal excitation model (Kaiser expression) to fit the temperature and electric-field dependent I–V curves. It is found that the I–V data measured at higher temper-atures or higher voltages can be well fitted by the Kaiser expression. However, the low-temperature data around the zero bias clearly deviate from those obtained from this model. The deviation (or zero-bias conductance suppression) could be possibly ascribed to the occurrence of the Coulomb-gap in the density of states near the Femi level and/or the enhancement of electron-electron interaction resulting from nanosize effects, which have been revealed in the previous studies on low-temperature electronic transport in conducting polymer films, pellets and nanostructures. In addition, similar I-V characteristics and deviation are also observed in an isolated K0.27MnO2 nanowire.  相似文献   
5.
水和乙醇对纳米管结构聚苯胺电阻率的影响   总被引:2,自引:0,他引:2       下载免费PDF全文
研究了水和无水乙醇对萘磺酸掺杂的纳米管结构聚苯胺的电阻率-温度依赖关系的影响(测量温区为80—300K).实验结果表明,水分子和乙醇分子的进入均使样品的电导率升高.利用电荷能量限制隧道模型结合纳米管粉末压片的结构特点,认为样品电阻主要来源于纳米管间接触电阻.水或乙醇分子在纳米管聚苯胺中通过与分子链的相互作用,增加了链间与链上非局域化载流子的数量,增大管间接触界面,降低了载流子的隧穿势垒,进而提高了导电能力.但水和乙醇对样品导电性质影响程度是不同的,主要是因为水分子和乙醇分子在结构和物理化学性质上的不同. 关键词: 聚苯胺 纳米管 电阻率  相似文献   
6.
萘磺酸掺杂对纳米管结构聚苯胺低温电阻率的影响   总被引:5,自引:0,他引:5       下载免费PDF全文
通过研究用自组装法制备的萘磺酸掺杂的纳米管结构聚苯胺(苯胺与萘磺酸的摩尔比分别为1∶025,1∶05,1∶1,1∶2,1∶3)的电阻率温度依赖关系(测量温区为80—300K),仔细分析聚苯胺的结构形貌特征,提出了变程跳跃隧道穿透混合模型:认为在萘磺酸掺杂的纳米管结构聚苯胺样品中,跳跃和隧穿两种机制同时起作用,载流子沿纳米管传导是变程跳跃过程起主要作用,而载流子在纳米管之间的传导是隧穿过程起主要作用.实验结果表明,不同浓度的萘磺酸掺杂对样品的低温电阻率的影响很大,随着掺杂浓度增加,载流子传导所需克服的能垒C0迅速减小,当掺杂接近饱和时,C0不再减小.实验中还研究了不同形貌对电阻率的影响,结果表明样品中纳米管所占比例的增大有利于载流子传导 关键词: 聚苯胺 纳米管 低温电阻率  相似文献   
7.
This paper studies the electronic transport in an individual helically twisted CdS nanowire rope, on which platinum microleads are attached by focused-ion beam deposition. The current-voltage (I - V) characteristics are nonlinear from 300 down to 60 K. Some step-like structures in the I - V curves and oscillation peaks in the differential conductance (dI/dV - V) curves have been observed even at room temperature. It proposes that the observed behaviour can be attributed to Coulomb-blockade transport in the one-dimensional CdS nanowires with diameters of 6-10 nm.  相似文献   
8.
Results of charge-transport and magnetic measurements of nanotubular polyaniline (PANI) composites containing Fe_3O_4 nanoparticles (~10nm) synthesized by a "template-free" method are reported. The T^{-1/2} resistivity has been observed, and dc magnetic susceptibility data are fitted to an equation χ=χ^*_P+C/T. With increasing weight ratio of Fe_3O_4, the electrical conductivity and temperature- independent susceptibility χ^*_P increase, and the Curie-type susceptibility is suppressed at low temperatures. Further discussions have been given. The PANI-H_3PO_4/Fe_3O_4 composite containing 27wt% of Fe_3O_4 nanoparticles is superparamagnetic, exhibiting very little hysteresis even at 5K.  相似文献   
9.
偶氮液晶聚合物中的非线性光致双折射   总被引:1,自引:0,他引:1       下载免费PDF全文
介绍了在偶氮液晶聚合物薄膜P-CN中发现的非线性光致双折射现象,给出了非线性光致双折射实验的具体结果.采用Z扫描技术验证了光致双折射的非线性过程本质,测量了P-CN介质薄膜的非线性吸收系数.讨论了光致双折射涉及的异构化微观机理,并在此基础上提出了非线性光光异构化实现光致双折射的方法 关键词: 液晶聚合物 光致双折射 光致异构化  相似文献   
10.
Poly(vinylpyrrolidone)/tetrabutyl titanate (PVP/ [CH3(CH2)3O]4Ti) composite nanofibres are prepared by elec- trospinning. After calcining parts of composite nanofibres in air at 700 C, petal-like TiO2 nanostructures are obtained. The characterizations of composite nanofibres and TiO2 nanostructures are carried out by a scanning electron micro- scope, an x-ray diffractometer, and an infrared spectrometer. Electrospun nanofibres are pressed into pellets under different pressures in order to explore their dielectric properties. It is found that the dielectric constants decrease with frequency increasing. The dielectric constant of the composite nanofibre pellet increases whereas its dielectric loss tangent decreases due to the doped titanium ions compared with those of pure PVP nanofibre pellets. In addition, it is observed that the dielectric constant of the composite nanofibre pellet decreases with the increase of the pressure applied in pelletization.  相似文献   
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