毫米级栅型电场分布FEP薄膜驻极体的制备及其电荷存储性能研究

采用电晕注极和热注极技术,在厚度为25μm的氟化乙丙烯共聚物(FEP)表面制备了宽度为2 mm和3mm的具有栅型电场分布的驻极体,研究了注极温度和电极宽度对其电荷存储性能的影响.样品注极后经150天的存储,栅型电场分布变得清晰而有规律,覆盖铝电极区电位已衰减至接近零,未覆盖铝电极区仍保持高电位;对电极宽度为2 mm和3 mm的样品,覆盖铝电极区与未覆盖铝电极区的表面电位差分别为110 V和130V(电场强度差分别为44 k V/cm和52 k V/cm).表面电位跟踪测试结果表明:电晕注极样品初始表面电位高于热注极样品;在相同的注极方法下,注极温度越高初始表面电位越高,电极宽度越小初始表面电位越低.依据电晕注极和热注极原理对实验结果的分析表明,FEP和金属铝在电荷存储性能上的差异是FEP表面蒸镀铝电极后能获得栅型电场分布的原因所在.

高压直流电缆用LDPE/EPDM复合绝缘材料的性能研究

为改性高压直流电缆与复合介质之间的空间电荷积聚,规避绝缘击穿的问题,采用开炼式熔融共混法和热压成型方法制备LDPE/EPDM复合绝缘材料,探究表层分子结构改性对LDPE/EPDM界面电荷性能的调控机理及规律。结果表明,经过表层分子改性的LDPE/EPDM电荷积聚性能有明显改善,但是受改性时间和试样匹配的影响,其呈现先上升后下降的趋势,存在既定的临界值,由此引致的电场畸变性存在显著差异。该结论对于LDPE/EPDM复合绝缘材料性能的优化设计具有指引作用。

聚丙烯薄膜的表面结构与驻极体性能相关性研究

以聚丙烯颗粒为原料、表面纳米化石英玻璃为模板,通过热压法制得表面具有不同形貌的聚丙烯薄膜,再经电晕充电形成驻极体。采用原子力显微镜技术分析了薄膜的表面结构,并用表面电位跟踪和热刺激放电技术测试了不同表面结构聚丙烯薄膜的电荷存储性能。表面电位测试结果表明,其电荷存储性能与薄膜表面的微观结构密切相关,薄膜表面越粗糙,捕获电子的能力越强,但其电荷存储稳定性差异不大。热刺激放电技术测试结果表明,其陷阱能级与表面粗糙度无关。

N_2O气氛退火对SONOS非易失性存储器性能的优化研究

SONOS(Silicon-Oxide-Nitride-Oxide-Silicon)型非易失性存储器件的电荷保持能力与Si-SiO2界面态的质量密切相关。通过在SONOS的隧穿氧化层工艺流程中增加适当的N2O退火工艺,改善了器件的擦除深度和编程速度,从而使得SONOS器件的存储器性能得到优化。通过进一步电荷泵测试表明,电荷泵电流值Icp由1.8×10-6A减小到1.3×10-6A,减小27.8%,即隧穿氧化层与衬底之间的界面态显著减少。因此,在SONOS工艺中增加适当的N2O退火工艺,能有效地优化存储器的存储能力,提高SONOS存储性能。

Effect of ultrasonic on structure and electrochemical performance of α-Ni(OH)_2 electrodes

Al/Co co-doped α-Ni（OH）2 samples were prepared by either ultrasonic co-precipitation method （Sample B） or co-precipitation method （Sample A）. The crystal structure and particle size distribution of the prepared samples were examined by X-ray diffraction （XRD） and laser particle size analyzer, respectively. The results show that Sample B has more crystalline defects and smaller average diameter than Sample A. The cyclic voltammetry and electrochemical impedance spectroscopy measurements indicate that Sample B has better electrochemical performance than Sample A, such as better reaction reversibility, lower charge-transfer resistance and better cyclic stability. Proton diffusion coefficient of Sample B is 1.96×10-10cm2/s, which is two times as large as that （9.78×10-11cm2/s） of Sample A. The charge-discharge tests show that the discharge capacity （308 mA·h/g） of Sample B is 25 mA·h/g higher than that of Sample A （283 mA·h/g）.

Pb^(2+)与Al^(3+)掺杂对SiO_2薄膜电荷贮存性能的影响

较高的表面能是ＳｉＯ２薄膜产生亲水性并导致体内贮存电荷失稳的重要原因。极性Ｐｂ２＋离子的掺入有效地降低了ＳｉＯ２薄膜的表面能，使表面趋于中性，增强了疏水性。此外，Ｐｂ２＋、Ａｌ３＋离子作为填隙式离子和替位式离子的掺入较好地改善了ＳｉＯ２薄膜的网络结构并使其致密化，使样品在保持原有良好的负电荷存储性能基础上，又对称地增加了优良的正电荷贮存能力。这表明降低表面能和增强网络结构是提高ＳｉＯ２薄膜驻电性能的有效途径，ＳｉＯ２ＰｂＯＡｌ２Ｏ３复合膜有希望成为一种新型无机驻极体材料。

Nonlinear Current-Voltage Characteristics and Electroluminescence of cBN Crystal

The current-voltage（I-V） characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, and the resulting curves are all similar in shape. When a voltage of about 560V is applied to the cBN crystal, the emitted light is visible to the naked eye in a dark room. We explain these phenomena by the space charge limited current and the electronic transition between the X and Г valleys of the conduction band.

熔喷非织造布的驻极技术研究进展

为深入了解熔喷非织造布的驻极技术研究现状,系统综述了熔喷非织造布的驻极技术、熔喷非织造布的电荷存储性能及驻极熔喷非织造布的发展前景;归纳了电晕充电、摩擦起电、静电纺丝和水驻极等6种驻极技术的特点与驻极机制,重点剖析了电晕驻极和水驻极处理技术和应用现状;介绍了静电存储及其稳定性的机制,进一步分析了驻极体材料、驻极工艺、聚合物晶体结构对熔喷非织造布静电存储性能的影响。此外,针对目前驻极技术在应用领域面临的挑战指出,开发多功能、高附加值的新型驻极材料和多重驻极技术结合是驻极熔喷非织造布未来的主要发展方向。

Specific Heat and Charge Density of Quasi-One-Dimensional Interchain Coupling Organic Ferromagnets

On the basis of a generalized SSH model, an organic polymer ferromagnet theory is proposed at the finite temperature in the self-consistent mean field approximation, and the specific heat and charge density of the quasione-dimensional interehain coupling organic ferromagnets are presented. We find that an obvious feature is to present itself the round peak for the specific heat with the temperature. This indicates unambiguously the presence of the phase transition in the system. The transition temperature plays down with increasing of the interchain coupling t2 or decreasing of the electron repulsion u. The curves of charge density with the temperature debase monotonously. This result illustrates that the higher the temperature is, the more electrons are excited.

Effects of Sintering Atmosphere on the Microstructure and Surface Properties of Symmetric TiO2 Membranes

The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerimental results show that the symmetric TiO2 membranes display better sintering activity in the air than in argon, and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature. The surface compositions of the symmetric TiO2 membrane sintered in the air and in argon at different temperatures, as studied by X-ray photoelectron spectroscopy, are discussed in terms of their chemical composition, with particular emphasis on the valence state of the titanium ions. The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti^3＋, introduced at the surface of the symmetric TiO2 membranes by sintering in a lower partial pressure of oxygen, is related to a significant decrease in the isoelectric point. TiO2 with Ti^4＋ at the interface has an isoelectric point of 5.1, but the non-stoichiometric TiO2-x with Ti^3＋ at the interface has a lower isoelectric point of 3.6.

Experimental investigation of effect of refrigerant gases,compressor lubricant and operating conditions on performance of a heat pump

In the field of heat pumps,there are a number of parameters that affect the performance and efficiency of the apparatus,which have been the subject of studies by individual researchers in the literature.This study describes an experimental method in order to investigate the effects of some significant parameters on heat pump performance.In this regard,a laboratory heat pump setup has been utilized to operate in different working conditions for achieving an appropriate estimation to find out effects of mentioned parameters such as refrigerant type and charge amount,compressor oil viscosity,compressor cooling fan,secondary fluids temperature and flow rate.Different refrigerants have been selected and used as circulating fluid in the installed heat pump.Although this work has been devoted to a detailed attempt to recognize the effects of various parameters on the coefficient of performance(COP) value,an appropriate method has been carried out to survey the obtained results by using economic analysis.It was revealed that one of the main parameters is refrigerant charge amount which has a notable effect on COP.The temperature of the heat source was also tested and the performance of the system increased by more than 11% by employing mentioned modifications and various operating conditions.In addition,by selecting a low viscosity compressor oil,the system performance increased by 18%.This improvement is more than 6% for the case that cooling fan is installed to cool the compressor element.

First-principles study on mechanical properties of LaMg_3 and LaCuMg_2

Abstract： With the substitution of part Mg in LaMg3 by Cu, the elastic constants CH and C12 increase while C44 decreases, implying an enhanced Poisson effect and smaller resistance to 〈001〉（100） shear. Furthermore, the bulk modulus B increases, while the shear modulus G, elastic modulus E and anisotropie ratio A are reduced. The calculated Debye temperature of LaCuMg2 is lower, implying the weaker interaction between atoms in LaCuMg2. Then, the stress-strain curves in entire range and the ideal strength at critical strain are studied. The present results show that the lowest ideal tensile strength for LaMg3 and LaCuMg2 is in the 〈100〉 direction. The ideal shear strength on the 〈 1 ^-1 0〉（110） slip system of LaMg3 is greater than LaCuMg2. The density of states and charge density distribution are further studied to understand the inherent mechanism of the mechanical properties.

Electronic and Optical Properties of Cubic SrHfO_3

In order to clarify the mechanism of optical transitions for cubic SrHfO_3, we have investigated the electronicstructure and optical properties of cubic SrHfO_3 using the plane-wave ultrasoft pseudopotential technique based on thefirst-principles density-functional theory (DFT).The ground-state properties, obtained by minimizing the total energy,are in favorable agreement with the previous work.From the band structure and charge densities as well as the theoryof crystal-field and molecular-orbital bonding, we have systematically studied how the optical transitions are affected bythe electronic structure and molecular orbitals.Our calculated complex dielectric function is in good agreement withthe experimental data and the optical transitions are in accord with the electronic structure.

Factors Affecting Sensitivity of Variable Charge Soils to Acid Rain

The sensitivity of a large number of variable charge soils to acid rain was evaluated through examiningpH-H_2SO_4 input curves. Two derivative parameters, the consumption of hydrogen ions by the soil and theacidtolerant limit as defined as the quantity of sulfuric acid required to bring the soil to PH 3.5 in a 0.00lmolLi￣(-1) Ca(NO_3)_2 solution, were used. The sensitivity of variable charge soils was higher than that of constantcharge soils, due to the predominance of kaolinite in clay mineralogical composition. Among these soils thesensitivity was generally of the order lateritic red soil >red soil >latosol. For a given type of soil within thesame region the sensitivity was affected by parent material, due to differences in clay minerals and texture.The sensitivity of surface soil may be lower or higher than that of subsoil, depending on whether organicmatter or texture plays the dominant role in determining the buffering capacity. Paddy soils consnmedmore acid within lower range of acid input when compared with upland soils, due to the presence of moreexchangeable bases, but consumed less acid within higher acid input range, caused by the decrease in claycontent.

Economic Load Dispatch with Daily Load Patterns Using Particle Swarm Optimization

ELD （economic load dispatch） problem is one of the essential issues in power system operation. The objective of solving ELD problem is to allocate the generation output of the committed generating units. The main contribution of this work is to solve the ELD problem concerned with daily load pattern. The proposed solution technique, developed based PSO （particle swarm optimization） algorithm, is applied to search for the optimal schedule of all generations units that can supply the required load demand at minimum fuel cost while satisfying all unit and system operational constraints. The performance of the developed methodology is demonstrated by case studies in test system of six-generation units. The results obtained from the PSO are compared to those achieved from other approaches, such as QP （quadratic programming）, and GA （genetic algorithm）.

Exergetic Performance Analysis of a Cogeneration Plant at Part Load Operations

A cogeneration plant can run at off-design due to change of load demand or ambient conditions. The cogeneration considered for this study is gas turbine based engine consists of variable stator vanes （VSVs） compressor that are re-staggered for loads greater than 50% to maintain the gas turbine exhaust gas temperature at the set value. In order to evaluate the exergetic performance of the cogeneration, exergy model of each cogeneration component is formulated. A 4.2 MW gas turbine based cogeneration plant is analysed for a wide range of part load operations including the effect of VSVs modulation. For loads less than 50%, the major exergy destruction contributors are the combustor and the loss with the stack gas. At full load, the exergy destructions in the combustor, turbine, heat recovery, compressor and the exergy loss with stack gas are 63.7, 14.1, 11.5, 5.7, and 4.9%, respectively. The corresponding first and second law cogeneration efficiencies are 78.5 and 45%, respectively. For comparison purpose both the first and second law efticiencies of each component are represented together. This analysis would help to identify the equipment where the potential for performance improvement is high, and trends which may aid in the design of future plants.

基于星射状三苯胺敏化剂的分子设计

以性能优良的三苯胺星射状分子WD8为母体,通过密度泛函理论方法,探讨了取代基团在不同位置时,对母体分子电子性质、光谱性质和电荷传输性能的影响.结果表明,取代基团位置的不同,对分子的前线分子轨道组成基本没有影响.当2-氰基-3-呋喃基-丙烯酸基团取代位置由对位变为间位时,分子的吸收范围最大.当2-氰基-3-呋喃基-丙烯酸基团和1个吩噻嗪-苯基团取代位置由对位变为间位时,分子的EHOMO最大,ELUMO和Eg最小,分子的最大吸收波长最长.当2-氰基-3-呋喃基-丙烯酸基团和2个吩噻嗪-苯基团取代位置由对位变为间位时,分子的电荷传输性能最强.

Cooperation of oxygen vacancies and 2D ultrathin structure promoting CO2 photoreduction performance of Bi4Ti3O12

Reduction of CO2to solar fuels by artificial photosynthesis technology has attracted considerable attention. However, insufficient separation of charge carriers and weak CO2adsorption hamper the photocatalytic CO2 reduction activity. Herein, we tackle these challenges by introducing oxygen vacancies (OVs) on the two-dimensional Bi4Ti3O12ultrathin nanosheets via a combined hydrothermal and postreduction process. Selective photodeposition experiment of Pt over Bi4Ti3O12discloses that the ultrathin structure shortens the migration distance of photo-induced electrons from bulk to the surface, benefiting the fast participation in the CO2reduction reaction. The introduction of OVs on ultrathin Bi4Ti3O12 nanosheets leads to enormous amelioration on surface state and electronic structure, thereby resulting in enhanced CO2adsorption, photoabsorption and charge separation efficiency. The photocatalytic experiments uncover that ultrathin Bi4Ti3O12nanosheets with OVs reveal a largely enhanced CO2photoreduction activity for producing CO with a rate of 11.7 lmol g-1h-1in the gas–solid system, 3.2 times higher than that of bulk Bi4Ti3O12. This work not only yields efficient ultrathin photocatalysts with OVs, but also furthers our understanding on enhancing CO2reduction via cooperative tactics.

Effect of high temperature annealing on the performance of MANOS charge trapping memory

We have investigated the effect of post deposition annealing (PDA) temperature of Al2O3 blocking layer on the performance of charge trapping memory capacitors. Two splits of PDA were performed in N2 ambient at 850°C/60 s and 1050°C/60 s, respectively. The 1050°C annealed capacitor could be programmed and erased normally by using Fowler-Nordheim (FN) injection. In contrast, the 850°C annealed device could not be erased, even though it could be programmed properly. By measuring the gate leakage current and the flatband voltage shift, we found the erase failure in the 850°C annealed device was due to a larger gate back-injection leakage current at Vg<0. The trend of gate leakage current was further verified in two Al/Al2O3/SiO2/p-Si control capacitors with the same PDA splits. In addition, constant voltage stress measurements on control capacitors in the FN regime showed that the change of gate leakage current followed an empirical Curie-von Schweidler law at Vg<0. The data pointed out the importance to further study the relation between PDA conditions and the defect generation properties in Al2O3 blocking layer.