The influence of dipolar species on charge carrier transport in alinear polysilicon

Effect of polar substituents and polar dopants on the transport of charge carriers in poly[methyl(phenyl)silanediyl] (PMPSI) was studied. The transport in undoped PMPSI can be explained within the theory of disordered polarons which postulates that the temperature and field dependence of the charge carrier mobility contain contributions both from the dynamic disorder, i.e. the polaron barrier, and from the environment-dependent static disorder. Polar moieties, chemically attached to the main polymer chain, give rise to a decrease of the on-chain mobility, due to the formation of local electronic polarization states. On the macroscopic level, these moieties and polar dopants give rise to a decrease of the drift (hopping) mobility due to a broadening of the distribution of the density of transport states as a consequence of the electrostatic interaction of the charge carrier with the dipole     

Relaxation of excitons and charge carriers in polymers

In this paper various aspects of relaxation of optically generated excitations in random organic solids are discussed. Examples are spectral diffusion of excitons in organic glasses, or conjugated polymers, involving energy transfer within an inhomogeneously broadened dense manifold of chromophores, and charge carrier transport in random photoconductors. After an outline of the concept of time dependent random walks within an energetically and spatially disordered array of hopping sites, recent results on charge and exciton transport in π-conjugated systems such as conjugated polymers will be presented. The main emphasis will be on site-selective methods. Site selectivity, achieved by means of a spectrally tunable excitation source, is an unique opportunity to identify a subensemble of excitations which will be able to undergo subsequent relaxation probed by time-dependent spectroscopy     

LiFe1-xMgxPO4/C载流子输运性质的研究

以Mg2+为Fe位掺杂离子,聚乙二醇400(PEG400)为碳源,采用液相法合成了LiFe1-xMgxPO4/C复合正极材料。通过X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、电化学阻抗(EIS)等手段对材料的结构、形貌和载流子的输运性质等进行了表征。考察了掺碳量和掺Mg2+量对于目标化合物的电子电导率和Li+扩散性质的影响。结果表明:掺碳有利于改善材料的电子电导率,掺碳后材料的电子电导率比掺碳前提高了近7个数量级;Mg2+掺杂有利于改善材料的Li+扩散性和离子电导率,掺杂10%(摩尔分数)Mg2+材料的电荷迁移电阻Rct由掺杂前的190 W减小到74 W。     

Tailoring the properties of quantum dotmicropillars by ultrafast optical injection of free charge carriers

We review recent studies of cavity switching induced by the optical injection of free carriers in micropillar cavities containing quantum dots. Using the quantu...     

TLM modelling of diffusion,drift and recombination of charge carriers in semiconductors

The paper provides an extension to the one-dimensional TLM diffusion model. The extended diffusion node presented here models the exact transport equation with diffusion drift and recombination of charge carriers in semiconductors. A general algorithm for providing a numerical solution to the transport phenomena is also presented here. The analytical solution for infinitely long semiconductors is compared with the TLM numerical results.     

Effect of polyethylene interface on space charge formation

This paper reports on an investigation into the space charge formation and decay at different material interfaces. In particular, the influence of the interface between electrode and polymer or polymer and polymer on the space charge dynamics has been studied. Planar samples were subjected to high DC electric stresses for extended periods of time and space charge measurements taken using the pulsed electroacoustic (PEA) technique. It has been found that the types of interface between electrode and polymer play a significant role in determining the charge distribution in the insulation and that the interface between polymer and polymer acts as a potential barrier to electrons while allowing positive charge carriers through easily.     

负极添加剂对牵引型蓄电池充电接受能力的影响

通过充电对比试验 ,探讨了无机膨胀剂BaSO4、导电物炭黑及有机膨胀剂对牵引型铅酸蓄电池充电接受能力的影响 ,并优化了提高充电接受能力的负极配方。     

富锂锰基材料充电过程中的动态R_(ct)

以过渡金属乙酸盐原料,通过溶胶-凝胶法制备了两种富锂锰基正极材料Li[Li0.13Co0.61Mn0.26]O2和Li[Li0.2Co0.4-Mn0.4]O2,采用XRD、SEM和电化学技术对所得样品的结构、形貌及电化学性能进行了表征和分析。结果表明富锂锰基材料为层状固熔体,且一次颗粒粒径为纳米级。采用恒电流法研究充电过程中材料电荷转移阻抗的变化,结果表明:在充电过程中富锂锰基正极材料电荷转移阻抗先增大后减小,当SOC大约在30%~50%时Rct达到最大,分别约为2 164~4 341Ω和4 254~6 741Ω,而在其余状态下Rct相对较低。     

A generalized analytical model based on multistage scattering phenomena for estimating the impact ionization rate of charge carriers in semiconductors

A generalized analytical model based on multistage scattering phenomena has been developed in this paper for estimating the impact ionization rate of charge carriers in semiconductors. The probabilities of impact ionization initiated by electrons and holes have been calculated separately by taking into account all possible combinations of optical phonon scattering and carrier-carrier collisions prior to the impact ionization. Finally the analytical expressions of impact ionization rate of electrons and holes have been developed by using the aforementioned impact ionization probabilities. The impact ionization rates of electrons and holes in 4H-SiC have been calculated within the field range of \(2.5\times 10^{8}\) – \(6.5\times 10^{8}\hbox { V m}^{-1}\) by using the analytical expressions of those developed in the present paper. Those are also calculated by using the analytical expressions developed by some other researchers earlier without considering the multistage scattering phenomena. Finally the theoretical results obtained from the analytical model proposed in this paper and the analytical model developed by earlier researchers within the field range under consideration have been compared with the ionization rate values calculated by using the empirical relations fitted from the experimentally measured data. Closer agreement with the experimental data has been achieved when the impact ionization rate of charge carriers in 4H-SiC are calculated from the proposed model as compared to the earlier one.     

脉冲充电对铅酸蓄电池硫酸盐化的影响

设计了一种消除铅酸蓄电池硫酸盐化故障的脉冲充电实验方法 ,其脉冲电流的大小和周期介于正常电池的脉冲充电法和传统的消除硫酸盐化的反复充放电法之间 ,并用该法与传统方法进行对照实验。实验结果表明 ,脉冲充电法充入的电量仅为传统方法的 42 % ,但各个单体电池的电解液密度上升幅度平均为传统方法的 83 %。证明了脉冲充电法比传统方法能更有效地消除硫酸盐化 ,并由此推断出用脉冲充电法对正常电池进行恢复性充电 ,能起到防止硫酸盐化的作用 ,并延长铅酸蓄电池的循环寿命     

催化剂载体对DBFC性能的影响

直接硼氢燃料电池(DBFC),是一种新型的高比能便携式电源,其电池电势(1.64 V)及理论比能量(9 300 Wh/kgNaBH4)均高于直接甲醇燃料电池.为了实现BH4-的8电子完全氧化,分别以Ketjen炭黑、Vxc-72R炭黑为载体,采用溶胶-凝胶法制备了纳米级的Au/C催化剂,并采用分层装配的方法组装了单电池,考察了催化剂载体及载体处理对电池性能的影响.结果表明,溶胶-凝胶法是制备纳米级高分散Au/C催化剂的有效方法,Ketjen炭黑载体明显优于Vxc-72 R炭黑,载体经酸处理后可大大提高电池的性能.     

The incorporation of space charge degradation in the life model forelectrical insulating materials

The time function of the Eyring reaction rate theory of insulation life is modified to demonstrate a physical origin for temperature threshold. Various mechanisms by which trapped charges may be involved in degrading the polymer are examined, and incorporated into the life model through an alteration to the free energies of the reacting system. The corresponding life functions are shown to possess the field-dependent threshold form previously obtained phenomenologically for insulating materials. The physical interpretation of the model parameters is discussed     

有机膨胀剂对小型阀控铅蓄电池充电接受能力的影响

研究了有机膨胀剂如木素等对负极充电接受能力的影响。试验中发现,应用腐殖酸置换铅膏配方中1／3－1／2的VanisperseA能有效地抑制充电接受率的降低。     

Electrically active centers of capture of charge carriers and electret effect in polymeric dielectrics and mica

The results of an experimental investigation of the electret effect and electrically active centers of capture in polymeric dielectrics modified by radiation and subjected to deformation (X-ray radiation of electric gas barrier discharge using the EGBD technique), as well as mica after δCo⁶⁰ radiation and heat treatment, have been presented. It has been shown that electrically active centers of capture in polymeric electrets are polar C-H bonds and, in mica crystals, these centers are radiation defects of K⁺-OH⁻ ionic crystalline sublattice. It was shown that the process of the formation of polymeric and mica electrets is described by the wave-current model of polarization.     

Additional confirmation of a generalized analytical model based on multistage scattering phenomena to evaluate the ionization rates of charge carriers in semiconductors

This paper contains additional validations of a comprehensive analytical model based on multistage scattering phenomena to evaluate the impact ionization rates of charge carriers in semiconductors which was proposed by the authors and reported earlier. The model has been used to evaluate the ionization rates of both electrons and holes in some potential wide bandgap (WBG) semiconductors such as Wurtzite-GaN (Wz-GaN), type-IIb diamond and 6H-SiC. The numerical results obtained from the analytical model within the respective electric field ranges under consideration have been compared with the ionization rate values calculated by using the empirical relations fitted from the experimentally measured data. The calculated values of impact ionization rates of electrons and holes in all the WBG semiconductors under consideration are found to be in close agreement with the experimental results.     

热电池正极材料

过渡族金属硫化物是一类很好的热电池正极材料。利用热重分析(TGA)方法研究了矿物FeS2粉末与人工合成的CoS2的热分解特征,研究表明,矿物FeS2粉末的热分解温度在540 ℃,人工合成的CoS2的热分解温度在640 ℃;扫描电镜(SEM)分析表明人工合成的CoS2为近球形多孔网络状结构,而天然矿石的FeS2粉末表面光滑平坦;电化学性能测试表明,CoS2比FeS2更适于研制工作时间长、脉冲电流大的热电池。通过在正极中引入适宜的添加剂,采用合适的添加剂配比和添加工艺,可以研制出适用于有大负载、快激活要求的热电池正极材料。     

不同炭材料对铅蓄电池性能的影响

炭材料是铅蓄电池负极板重要的添加剂之一,优化其性能和添加量可有效改善电池综合性能。研究不同种类炭添加剂（乙炔黑、炭黑、活性炭）和添加比例（0．2％～0．8％）对铅蓄电池性能的影响。通过充电接受能力、-15℃低温容量、高倍率放电容量等表征电池性能。实验结果表明,不同炭材料对电池性能的影响趋势不同,相同添加量时,添加活性炭电池的充电接受能力最好。     

Effect of water inclusions on charge transport and polarization inporous media

Wideband dielectric spectroscopy measurements (100 Hz to 10 GHz) were carried out on different microporous systems (including sintered glass filters, sandstone and carbonate rocks) saturated with brine (electrolytic water solution) and a hydrocarbon oil at different relative fractions. Three main contributions were singled out in the dielectric spectra: low frequency dispersion (LFD) effects (<100 kHz) related to long range ionic transport and dependent on the connectivity of the water phase; Maxwell-Wagner-Sillars (MWS) polarization effects (100 kHz to 1 GHz), essentially controlled by the shape of the water inclusions; and high-frequency effects (>1 GHz) due to short-range ion transport and related to specific pore surface. For each analyzed system, oil-wet (o-W) and water-wet (w-w) samples were obtained by chemical treatment of the pore surfaces. Systematic differences were observed in the electrical response on varying wettability (and so the respective distribution of the fluids in the pore space). Parameters such as the loss tangent value, the strength and the exponent of the LFD power law, as well as the characteristic time and strength of the MWS relaxation were good indicators of wettability. Results were discussed by using some standard models that account for the pore wettability effects on dielectric spectra. A new method for wettability determination of reservoir rocks from both laboratory and borehole electric measurements was presented