Effect of barrier discharge on stability of electret state of high-density polyethylene

The electret state of high-density polyethylene subjected to an electric gas barrier of an AC discharge is studied. It is established that under the effect of the discharge a negative charge is formed on the film surface. Using thermally stimulated polarization, we study the space-charge processes in both the thermoand corono-electrets processed in the barrier discharge in the air gap between the dielectrics (glass–polyethylene). A comparison of the stability of the electret state in polyethylene films is carried out.     

Relaxation of the electret charges of PET films after the action of aerosol particles

The electret properties of PET films before and after the action of aerosol particles (APs) are investigated. These properties are shown to depend not only on the nature and method of the polymer polarizations but also on the variations in their micro- and permolecular structure (PMS). The singularities of the differences in the processes of the relaxation of stabilized electret charges in the bulk and in the surface layers of PET films have been revealed based on the results of the analysis of the spectrum of the thermostimulated depolarization (TSD) current. The thus-obtained data on the variations in the relaxation properties of electret PET film electrets allow us to say that these films can be used for fabricating efficient aerosol catches for different purposes and aerosol-sensitive sensors operating based on the principle of decreasing the values of the electret charges.     

Improvement of the Electret Properties of Polystyrene with Introduction of Titanium Dioxide

The electret properties of polystyrene composites with titanium dioxide were studied. The optimal parameters were defined for manufacturing corona electrets based on polystyrene. The introduction of 2–10 vol % titanium dioxide into polystyrene resulted in better electret performance owing to an increased portion of polymer macromolecules with a reduced mobility, the appearance of interphase polarization, and the formation of high-energy traps at the polymer–filler interphase boundary. It was shown that the thermal stability of the electret properties significantly increased for the polystyrene filled with titanium dioxide.     

Effect of the electrothermopolarization on the electret properties and the charge state of polyethylene nanocomposites with Cr and PbCrO4 additives

The results of studying the effect of electrothermopolarization on the electret properties and charge state of PE + Cr and PE + PbCrO₄ composites are described. It is shown that an increase in the polarization field intensity to E _p = 5 × 10⁶ V/m leads to an improvement in the polarization processes in the composites; at E _p > 5 × 10⁶ V/m, the space charge concentration apparently increases, which results in the deterioration of the electret properties. The observed effect can be attributed to the repeated electron capture by deeper traps owing to the internal electric field. In addition, the intensity of the TSD peaks and therefore the number of stabilized charges for the composites polarized at high intensities are higher than for the samples polarized at low intensities.     

Electrothermopolarization influence upon the structure and properties of a composition on the basis of polyethylene and Co(AlO<Subscript>2</Subscript>)<Subscript>2</Subscript>

The influence of electrothermopolarization on the structure and properties (electret, strength) of a composition on the basis of polyethylene and a low-molecular dye Co(AlO₂)₂ was investigated. It was experimentally established that the additive Co(AlO₂)₂ changes the polyethylene structure. As a result, the electret properties of the composition change. Correlation of the strength properties with the changes of the degree of the crystallinity of the polyethylene was observed.     

纳米银/环氧树脂复合电介质的电导特性

研究了纳米银(Ag)/环氧树脂(EP)复合材料的直流体积电阻率和强场电导。结果表明,在环氧树脂中微量添加小尺寸的银纳米粒子后,复合材料的体积电阻率比纯环氧树脂有明显提高,并且电阻率的增加与银粒子尺寸、含量,以及基体聚合物的特性有关。对复合材料强场电导的研究表明,小尺寸的银粒子在聚合物中分散良好时,复合物的强场电导表现出库仑阻塞特性,即纳米粒子可限制载流子的迁移。而当纳米粒子的粒径过大或添加较多时,复合材料在强电场下表现出对电荷的捕获与脱陷,具有明显的空间电荷限制电流特性。热刺激电流特性反映出纳米粒子与聚合物在界面处形成深陷阱是产生空间电荷限制电流的原因     

Polycarbonate-based conductive film prepared by coating DBSA-doped PEDOT/sorbitol

A series of conductive polycarbonate films (CPCFs) were prepared by spin coating with an ethanol-based coating solution comprised of dodecylbenzenesulfonic acid-doped poly(3,4-ethylenedioxythiophene) (PEDOT)/sorbitol. The variation of CPCF surface resistivity was then measured as a function of temperature. CPCF surface resistivity decreased as sorbitol content increased, with the minimum values in the temperature range 175–185 °C. Furthermore, the CPCF-1.6 exhibited significantly improved thermal stability with respect to surface resistivity even at 175 °C. FT-IR analysis indicated that, after thermal treatment, hydrogen bonds arising from the hydroxy groups of sorbitol or hydroxypropyl cellulose and carbonyl groups of polycarbonate were established. The combination of surface resistivity data and FT-IR analysis suggests that the introduction of sorbitol accompanied with thermal treatment allows the PEDOT chains to undergo favorable inter-chain interactions leading to charge transfer and physical cross-linkage via hydrogen bonding.     

Electrical,optical and hole transport mechanism in thin films of poly(3-octylthiophene-co-3-hexylthiophene): Synthesis and characterization

The present study demonstrates the designing of copolymer poly(3-octylthiophene-co-3-hexylthiophene) (P3OT-HT) and study of the hole transport mechanism in it. Detailed structural, optical and thermal studies of P3OT-HT discuss its synthesis aspects. Current density–voltage characteristics have been studied at different temperatures (290–110 K) to understand the mechanism of hole transport in P3OT-HT. It has been established that current density in P3OT-HT thin films is governed by space charge limited conduction with traps distributed exponentially in energy and space. Hole mobility is both temperature and electric field dependent arising due to substituent functional groups attached the polymer backbone.     

金属含量对Co-TiO2纳米颗粒复合薄膜微观结构及其性能的影响

目的使Co-TiO_2纳米颗粒复合薄膜同时具备高的磁化强度及电阻率,从而实现更好的高频软磁特性。方法通过磁控共溅射的方法,在不同金属靶功率下制备了Co-TiO_2纳米颗粒复合薄膜,并探究金属含量对薄膜的微观结构、表面形貌、电学和静态磁学性能的影响。结果薄膜中的金属颗粒被非晶态的TiO_2分散。金属含量的增加可以显著提高纳米颗粒薄膜中金属颗粒的结晶性,降低薄膜电阻率,并且通过改变金属含量,可使薄膜逐渐从超顺磁态向铁磁态转变,达到精确调控纳米颗粒复合薄膜的磁学和电学性能的目的。结论在金属含量达到54%时,实现了高电阻率和高饱和磁化强度共存,有望得到具有高频软磁特性的纳米颗粒复合薄膜。     

Gas barrier properties and periodically fractured surface of thin DLC films coated on flexible polymer substrates

Thin DLC films coated on polymer surfaces are attracting considerable attention due to their wide applications and their interesting surface properties. When DLC films were coated on polymers, the resulting DLC-polymer composites are highly functionalized materials, some of which presenting dramatically improved gas barrier properties.In this paper, we will introduce several commonly used polymers including polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) for semi-crystalline polymers, and polymethyl methacyrlate (PMMA) for an amorphous polymer. The polymers were coated with thin DLC films and the gas barrier properties of the resulting DLC-polymer composites were investigated. Some of the DLC-polymer composites dramatically improved their gas barrier properties while they presented horizontal crack lines and vertical micro-buckling lines on the DLC surface when stretched to a certain strain. The gas barrier properties of the DLC-polymer composites with fractured DLC surface were also studied. It was found that the gas barrier property of the polymer substrates with lower residual strains was less damaged, when the substrates were mechanically deformed, than that of the polymer substrates with higher residual strains. When the number of the cracks increases, the strain imposed on each crack decreases, since the overall deformation is almost equally distributed to each crack while the crack spacing of each crack becomes shorter. Thus, it was found that the degradation of the gas barrier property after mechanical deformation is dependent on the residual strain of the polymers and the number of cracks on DLC films.     

Modification of the charge state and thicknesses of the polymer polyethylene interlayer in piezoceramics with various structures after their electric treatment

The variations of the charge state and the thicknesses of the polymer polyethylene interlayer in piezoceramics with different structures due to their electric treatment have been investigated. It is shown that the differences of the strength properties of the piezocompositions with various particle dimensions dependent on the field strength of the electric treatment are associated with the variation of the specific surface of the polymer interlayer. The fraction of the interfaces of the polymer matrix with the equal volume content of the piezoceramics increases with the decreasing of the dimensions of the piezoceramic particles. This leads to the increasing of the interphase interactions between the components of the composite.     

Zn靶与掺铝ZnO靶共溅射制备ZnO:Al薄膜及其性能

采用Zn靶和ZnO(掺2%Al2O3(质量分数))陶瓷靶在玻璃衬底上共溅射沉积Al掺杂ZnO薄膜,即ZnO:Al透明导电薄膜,研究Zn靶溅射功率(0～90 W)和衬底温度(室温、100℃和200℃)对薄膜结构、形貌、光学和电学性能的影响。结果表明:按双靶共溅射工艺制备的ZnO:Al薄膜的晶体结构均为六角纤锌矿结构,且随着Zn靶溅射功率的增加,薄膜的结晶质量呈现出先改善后变差的规律,薄膜中的载流子浓度逐渐升高,电阻率逐渐降低,而薄膜的光学性能受其影响不大;随着衬底温度的升高,薄膜的结晶性能得到改善,薄膜的可见光透过率增强,电阻率降低。     

Effects of thermal treatment on the characteristics of boron and tantalum-doped ZnO thin films deposited by the electrospraying method at atmospheric pressure

Metal-doped (B and Ta) ZnO thin films were deposited by the electrospraying method onto a heated glass substrate. The structural, electrical and optical properties of the films were investigated as a function of dopant concentration in the solution and also as a function of annealing temperature. The results show that all the prepared metal-doped ZnO films were polycrystalline in nature with a (0 0 2) preferred orientation. As the amounts of dopant were increased in the starting solution, the crystallinity and transmittance decreased. On the other hand, heat treatment of the films enhanced the transmittance, Hall mobility, carrier concentration and crystallinity. It was also observed that 2 at.% is the optimal doping amount in order to achieve the minimum resistivity and maximum optical transmittance. As-deposited films have high resistivity and low optical transmittance. The annealing of the as-deposited thin films in air resulted in the reduction of resistivity. Depending on the characteristics of dopant, mainly ionic radius, the effects of dopant were studied on the properties of ZnO thin films. Boron and tantalum have been considered as dopants, tantalum being the superior of the two, since it showed the lower resistivity and higher carrier concentration as well as higher mobility. The minimum value of resistivity was 1.95 × 10^− 4 Ω cm (15 Ω/□) with an optical transmittance more than 93% in the visible region and minimum resistivity of 2.16 × 10^− 4 Ω cm (18 Ω/□) with an optical transmittance greater than 96% for 2 at. % tantalum- and boron-doped ZnO films respectively. The present values of resistivities were closer to the indium tin oxide (ITO) resistivity and also closest to the lowest resistivity values among the ZnO films that were previously reported. The prepared films exhibit the good crystalline structure, homogenous surface, high optical transmittance and low resistivity that are preferable for optical devices.     

靶基距对柔性基底上脉冲激光沉积透明导电薄膜的影响

采用脉冲激光沉积法,控制靶基距分别为4,6,8 cm,在聚乙烯对苯二甲酸酯基底上沉积铟锌氧化物、铟锡氧化物和铝掺杂氧化锌薄膜,研究了靶基距对薄膜电学、光学、形态和结构特性的影响.结果表明:采用6～8 cm靶基距制备的TCO薄膜,在可见光范围内的光学透光率超过90％,电阻率约为5×10-4 Ω·cm;除了这些优良的电学和光学特性外,靶基距8 cm制备的薄膜均匀、光滑、附着好,且无裂缝或任何其它扩展的缺陷,适用于光电设备.     

无机复合纳米材料电致变色薄膜研究进展

开发循环稳定性好,着/褪色响应快,变色效率高的薄膜是电致变色材料的研究重点。与有机材料相比,无机材料的稳定性更强,实用性更好。通过构筑高孔隙率、低电阻率、大比表面积和多活性位点的微纳结构活性薄膜,能有效提高电致变色性能。本文阐述了电致变色器件的变色原理,详细介绍了介孔结构、纳米阵列结构及核壳结构等特殊微纳结构无机电致变色薄膜的性能优势和发展现状,进而探讨了微纳结构薄膜存在的瓶颈问题和发展趋势,有利于精准拓展研究思路,对推动无机电致变材料的发展与应用具有指导作用。     

Coronoelectrets based on composites of high density polyethylene with a TlGaSe<Subscript>2</Subscript> semiconductor filler

In the thesis reports concerning the results of the study of the thermally stimulated depolarization and electret properties of the compositions of HDPE + x%, where x = 1, 3, 5, 7, 10, it is found that the composites with x = 5 and 7 are valuable electret materials with a lifetime of 360 days, 50 times higher than the lifetime of pure high density polyethylene.     

Characteristics of the Structure and Properties of ZnSnO_3 Films by Varying the Magnetron Sputtering Parameters

Transparent conductive oxide ZnSnO_3 films were prepared by radio-frequency magnetron sputtering from powder targets and were characterized by X-ray photoelectron spectroscopy,X-ray diffraction,transmission electron microscopy,atomic force microscopy,surface profile,UV–Vis spectroscopy,and Hall effect.The structures of the films were either amorphous or nanocrystalline depending on sputtering parameters including deposition time,target power,chamber pressure,and the target–substrate separation.The average transmittance of the ZnSnO_3 films within the visible wavelength was approximately 80%and the resistivity of the ZnSnO_3 films was in the range of 10-3–10-4X cm.The structural,optical,and electrical properties of the ZnSnO_3 films could be adjusted and regulated by optimizing the sputtering process,allowing materials with specific properties to be designed.     

Study of Electrical,Mechanical, and Tribological Properties of CrN x Thin Films as a Function of Sputtering Conditions

The influences of chemical composition and deposition power on the electrical, mechanical, and tribological properties of sputtered chromium nitride (Cr-N) thin films that can be used for development of cryogenic temperature sensor are investigated. Cr-N thin films were deposited by DC reactive magnetron sputtering technique under various nitrogen gas flows (5-20 sccm) and deposition powers (200 and 250 W). Results of chemical composition showed that films produced with 5 and 10 sccm flow of nitrogen gas were substoichiometric, while at higher flows they were overstoichiometric. The surface morphology investigation showed that grains size and surface roughness increase with nitrogen gas flow, whereas deposition power has an inverse effect on both of these parameters. The electrical results demonstrated that the substoichiometric films had a positive temperature coefficient of resistivity, and the overstoichiometric films showed a negative temperature coefficient of resistivity. The films produced at higher deposition power of 250 W showed higher hardness and lower friction coefficient and scratch volume, while variation of nitrogen gas flow in the range of 5-20 sccm did not affect these properties, significantly.     

Electrochemical properties of the polypyrrole films doped with benzenesulfonate

The electrochemical redox behavior of the polypyrrole films doped with benzenesulfonate was investigated by cyclic voltammetry, the surface morphology of the films was characterized by AFM, and the interactions between pyrrole oligomers and the benzenesulfonate anion were modeled with quantum chemical methods. It is the first systematic study of the redox properties of this interesting system, somewhat of a model system with two complementing interactions (electrostatic and aromatic stacking). The influence of the electrodeposition charge and current density on the properties of the polymer film is explored. The voltammetric measurements show that redoxactivity of the polypyrrole films doped with benzenesulfonate anions is quite high, and markedly depends on the thickness of the film. Experiments with bilayered films show that electrode surface has an important but limited impact on the formation of organized compact structures.     

MICROSTRUCTURE AND PROPERTIES OF ANNEALED ZnO THIN FILMS DEPOSITED BY MAGNETRON SPUTTERING

1.IntroductionZnO especially in the form ofthin film shasbeen attracting attention because ofits m any applica-tions,such astransparentelectrodes,varistors,phosphors,gassensors,surface acousticw ave devicesandpiezoelectric actuators[1,2].M ore recently,re…