Effect of injecting electrodes on TSD behaviour of vacuum deposited PVF films

Depolarization behaviour of vacuum deposited polyvinyl fluoride (PVF) films has been studied as a function of nature of the electrode materials used during polarization such as copper, silver, aluminium and indium using the thermally stimulated discharge current (TSD) technique. TSD spectra of these films show a single relaxation peak centered around 430 ± 1 K with activation energies of ∼ 0.65 eV. The peak current and the charge associated with the relaxation peak depend strongly on the electrode material used. This has been attributed to the electrode-polymer interface barrier controlling the injection of the charge carriers into PVF films that results into space charge effects by subsequent trapping of the injected charge carriers at macroscopic distances. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

聚丙烯孔洞驻极体膜的化学表面处理及电荷稳定性

利用热刺激放电(Thermally Stimulated Discharge, TSD)电流谱、在线电荷TSD、电荷等温衰减测量和衰减全反射(Attenuated Total Reflection, ATR)红外光谱分析，本文系统地研究了经化学表面处理(萃取、氧化及氢氟酸)的聚丙烯(PP)孔洞驻极体膜的电荷储存稳定性及电荷稳定性提高的原因.结果表明：经适当地氧化和氢氟酸室温处理试样的TSD电流谱中在温位约为184℃处出现原膜所没有的非常强的新峰，电荷热稳定性得到显著的提高，这一电荷热稳定性通过高温充电工艺得到进一步地改善；适当延长室温下氢氟酸处理的时间或延长氧化时间，都会使处理膜的电荷稳定性得到提高.理论分析表明在线电荷TSD测量法可给出线性升温过程中电荷重心及驻极体电荷量变化的综合信息，结合TSD电流谱和初始电荷重心位置的测量，可精确地考察线性升温过程中电荷重心的在线变化. 关键词： 聚丙烯孔洞膜 表面氧化 氢氟酸处理 电荷稳定性 在线电荷TSD     

Thermoluminescence and thermally stimulated currents in PbMoO4 crystals

Thermally stimulated depolarization (TSD) currents have been studied in the range from 4 K to room temperature by utilizing direct contacts as well as blocking contacts. Charge carrier injection and subsequent trapping seem to be responsible for internal electric fields. A glow peak near 186 K arises from a dipolar relaxation. The results of additional optical excitation during polarization provide some more information on charge transport involved in relaxation processes. The correlation to the results of photoconductivity and annealing procedure leads to the assumption of oxygen vacancies as the dominant defect centres. The study of thermoluminescence (TL) after X-irradiation gives evidence on defect states in question. In addition, from the results quasi-free charge carriers are assumed to be thermally generated above 100 K.     

电晕充电多孔PTFE/PP复合驻极体过滤材料的电荷存储特性

报道采用电晕充电方法，对用高温熔融粘合工艺制备得到的双向拉伸多孔PTFE与PP复合过滤材料进行驻极体改性，并采用热刺激放电和表面电位测量等方法研究了材料的电荷存储稳定性,根据驻极体相关理论，对实验结果进行了解释. 结果表明，电晕充电的多孔PTFE/熔喷或纺粘PP覆膜材料中，既存在空间电荷又存在极化电荷，复合膜的界面是电荷陷阱的主要来源. 从不同面对复合膜材料进行充电时，材料具有完全不同的电荷存储特性. 由于材料体内空间电荷和极化电荷的极性相反、相互补偿，表面电位测定并不能真正反映材料内部电荷的存储状态. 关键词： 驻极体 电晕充电 聚合物复合膜 热刺激放电     

低密度聚乙烯热压成型过程中的空间电荷

借助开路热刺激放电(TSD)电流及原位实时电荷TSD和电荷等温衰减测量，研究了低密度聚乙烯(LDPE)在热压成型过程中所产生的空间电荷特性.结果表明具有良好室温稳定性的成型电荷被束缚在两类陷阱能级中：浅阱和深阱，其陷阱中心深度分别约为0.92eV和1.31eV.初步的分析进一步表明了它们应该分别位于试样的表层和体内，为近表面陷阱和体陷阱. 关键词： 低密度聚乙烯(LDPE) 热压成型 空间电荷 热刺激放电(TSD)     

氟气处理孔洞聚丙烯膜显著改善的电荷存储特性

通过衰减全反射(attenuated total reflection,ATR)红外光谱分析与开路热刺激放电(thermally stimulated discharge,TSD)电流、原位实时电荷TSD和电荷等温衰减的测量,研究了氟气对孔洞聚丙烯(PP)膜的氟化改性及氟化改性对其驻极性能的影响.研究结果表明：尽管在负压状态且较低的氟气分压及较低的反应温度(约60℃)和较短的反应时间(约15min)下,氟气能有效地氟化孔洞PP膜,更易于氟化预氧化的孔洞PP膜,氟化改性的孔洞PP膜,尤其是预氧化后的氟化改性 关键词： 孔洞聚丙烯膜 氟气 氟化改性 电荷稳定性     

Si基Si3N4/SiO2双层膜驻极体的电荷储存与输运

利用等温表面电位衰减及热刺激放电(thermally stimulated discharge,TSD)方法探讨了恒栅压电晕充电经常压化学气相沉积(APCVD)的Si基Si3N4和热生长SiO₂双层薄膜驻极体电荷的存储特性.结果表明:在常温环境中,300℃高温下,以及95%相对湿度时的60℃条件下,所有试样表现出极好的电荷储存稳定性.对于负电晕充电试样,其电荷输运受慢再捕获效应(slow retrapping effect)控制;用热离子发射模型来描述了正电晕充电Si₃N₄/SiO₂驻极体的正电荷输运特性. 关键词： 驻极体 薄膜 电荷储存 热离子发射     

Generation of surface plasmons in a conductor by moving charges

The surface polarization fields generated by a charge moving near a sphere or cylinder have been considered. This problem is related to the phenomena arising in an arc discharge in a gas near a solid surface during the formation of conducting cylindrical or spherical nanostructures, in particular, carbon nanotubes or fullerenes. The polarization fields, forces, energy losses, and other characteristics have been calculated.     

横向表面放电光泵浦源特性研究

 介绍了一种用以泵浦XeF(C-A)激光的横向表面放电辐射源,比较详细地研究了这种泵浦源的放电击穿特性、放电电流与充电电压及不同气体介质的关系、表面放电均匀性以及不同气体成分对表面放电辐射特性的影响。得到了放电击穿时间、放电峰值电流随充电电压、不同气体介质变化的曲线;分析了提高放电均匀性的途径,在电极长50cm、间距6cm、充电电压25kV条件下获得了均匀放电。获得了各种实验条件下放电辐射的光谱曲线;通过对辐射光谱的分析,研究了有利于光解离XeF₂的最佳实验条件,当p_Ar:p_N2=1:1时,放电在远紫外波段产生的辐射最强。     

Effect of Polarization Temperature on the Chain Segment Motion and Space Charge Detrapping in Polyamide 610 Film Electrets

The effect of polarization temperature on the chain segment motion and charge trapping and detrapping in polyamide 610 films has been investigated by means of thermally stimulated depolarization current (TSDC) and wide-angle X-ray diffraction (WAXD). A small part of the amorphous phase of quenched polyamide 610 changes into the crystalline state with increasing polarization temperature. There are three current peaks (named α, ρ₁, and ρ₂ peak, respectively) in the TSDC spectra. The α peak corresponds to the glass transition, the ρ ₁ peak is attributed to space charge trapped in the amorphous phase, and interphase between crystalline and amorphous phases, and the ρ ₂ peak originates from space charge trapped in the crystalline phase. By analyzing the characteristic parameters of these peaks, it was found that the increase of polarization temperature induced a decrease of the chain segment mobility and promoted the creation of structural traps in polyamide 610. The decrease of the chain segment mobility in the amorphous phase made the intensity of the α peak weak and the activation energy increased. The higher the polarization temperature, the higher the degree of crystallinity and the more charge carriers trapped in the crystalline phase. So, the increase of polarization temperature made the intensity of the ρ ₂ peak strong and increased the stability of trapped charge in the crystalline phase. The increase of polarization temperature also made the intensity of the ρ ₁ peak strong and decreased the stability of trapped charge in the amorphous phase and interphase.     

Electret properties and chemical modification of cellular polypropylene films

The electret properties of virginal cellular polypropylene (PP) films and chemically modified cellular PP films by extraction from CH₂Cl₂ solution, oxidation in a mixture solution of H₂SO₄, CrO₃ and H₂O and fluorination in a hydrofluoric acid (HF) solution, were systematically studied by measuring the open-circuit thermally stimulated discharge (TSD) current spectra, charge TSD spectra and isothermal charge decay. The results point out that there are more deep traps than shallow traps in the surface region while the contrary case occurs in the bulk region. The thermal stability of charge storage of the chemically modified cellular PP film is significantly improved in comparison with that of the virginal one. Light irradiation or reacting at elevated temperature has remarkable promotion effect on the reaction of HF with the extracted and oxidized film. Moreover, a method for investigating the dynamic changes of mean charge depth relative to its initial value during heating was proposed.     

恒流电晕充电对聚四氟乙烯多孔薄膜驻极体驻极态的影响

利用常温下恒流和恒压电晕充电、充电后的等温表面电位衰减、热刺激放电和扫描电镜等实 验手段研究了恒流和恒压电晕充电技术对聚四氟乙烯多孔薄膜驻极体驻极态的影响.与恒压电晕充电相比较，恒流电晕充电时由于流过薄膜的电流恒定，增加了注入电荷在多孔结构厚度方向界面处的俘获概率，使沉积电荷密度上升，改善了驻极体的储电能力.然而，这些位于不同层深多孔界面处的俘获电荷在这类功能膜储存或使用过程中，经外激发从脱阱位置 以跳动（hopping）模式输运至背电极的路径相对缩短将导致脱阱电荷衰减较快. 关键词： 恒流电晕充电 聚四氟乙烯多孔膜 驻极体 电荷稳定性     

A study of thermally stimulated currents in thin films of a good ionic conductor (βPbF2) with blocking electrodes

Thin film samples of βPbF₂ are studied by stimulated currents, the TSC peak of lower temperature, independent of the polarization voltage is attributed to the space charge depolarization. On the basis of simplifying hypothesis an exact analytical solution of this problem is also proposed; the comparison with the experimental results allows to get a value of the activation energy of mobile species and to estimate the thickness of the space charge. Electron transfers at the electrodes are assumed to explain the second peak.     

Transient and thermally stimulated depolarization currents in pure and iodine doped polyvinyl formal (PVF) films

Transient currents, measured with pure and iodine doped polyvinyl formal (PVF) films as a function of poling field (15–100 kV/cm) and temperature (30–95°C), have been found to follow Curie-von Schweidler law characterized with two slopes in short and long time regions. The isochronals (i.e. current/temperature plots at constant times) have been found to give rise to a peak located at 75°C. The order of current has been found to increase with increase in poling field, temperature and iodine mixing. The comparative studies of the isochronals with the thermally stimulated discharge current (TSDC) indicated the strong resemblance between the two studies. It is suggested that both the dipolar orientation due to molecular mechanism of motions with the side chains and space charge due to trapping of injected charge carriers in energetically distributed traps may be responsible for the observed currents. The dependence of current and activation energy on iodine mixing is explained on the basis of a charge transfer type of interaction.     

Thermally stimulated depolarization of a phosphate glass

Thermally stimulated depolarization (TSD) of phosphate glass of the composition 72·9% P₂O₅, 8·5% Al₂O₃, 18·6% CaO, 0·23% MnO has confirmed the existence of two types of slow relaxation. Migration polarization leads to TSD maximum near 0 °C, while the high temperature TSD maximum at 113 °C probably corresponds to space charge polarization. An analysis of the high temperature maximum shows that it is formed by a spectrum of relaxations with a single activation energy 1·0 eV, distributed over the dipole frequency factors with the most probable value ₀ 10¹⁰ sec^–1. Strong dispersion of permittivity points to the space charge polarization, though it is found that the effect is linear and independent of the sample geometry.The authors thank Dr. A.Bohun for the samples and for valuable advice.     

GaMnN铁磁共振隧穿二极管自旋电流输运以及极化效应的影响

通过理论计算研究GaMnN铁磁共振隧穿二极管自旋电流输运特性.理论结果表明在电流特性曲线上出现两个明显的自旋分裂峰.该电流自旋分裂峰和相应的自旋极化随温度的升高而逐渐减小消失.当进一步考虑到GaN异质结界面极化电荷影响时,自旋向下的电流共振峰得到明显增强,同时电流的自旋极化也得到相应的提高.在一定的极化电荷条件下,可以获得较高的自旋极化电流. 关键词： GaMnN 共振隧穿 自旋电流 极化电荷     

Effect of heating treatment on trap level distribution in polyamide 66 film electrets

The effect of heating treatment on the trap level distribution in polyamide 66 film electret is studied by thermally stimulated depolarization current （TSDC） technique. For annealed polyamide 66, there are three trap levels that respectively originate from space charge trapped in amorphous phase, interphase and crystalline phase. There is one peak that originates from space charge trapped in amorphous phase for quenched one. Using multi-point method to fit the experimental curves, the detrapping current peaks can be separated and the trap depth is obtained. The shallower trap levels trapped in amorphous phase and interphase are obviously close to the deeper trap level trapped in crystalline phase for annealed polyamide 66 as the polarization temperature increases, while the trap level distribution remains unaffected by polarization temperature for quenched one.     

实验研究大气压多脉冲辉光放电的模式和机理

采用稍不平行电极进行大气压He气介质阻挡多脉冲辉光放电实验,通过增强电子耦合器件相机短时曝光照片,研究大气压多脉冲辉光放电在不同时刻的放电模式.通过气隙放电电流、表面电荷计算,理论分析了表面电荷、空间电荷、外加电压与气隙电场强度的关系,研究大气压辉光放电形成多脉冲的机理.实验结果表明,放电首先在间隙稍窄的电极左端开始;在第一个脉冲电流峰值,电极右端也开始放电;第一个电流脉冲经历了Townsend放电到辉光放电的过程;电流脉冲之间的时间内,间隙一直维持着微弱的辉光放电;随后的每个电流脉冲均是辉光放电.理论分析表明,大气压辉光放电的多个电流脉冲是表面电荷、空间电荷与外加电压共同演化的结果;除放电伊始出现Townsend放电外,同一半周期内的放电电流脉冲中不会再出现Townsend放电.     

实验研究大气压多脉冲辉光放电的模式和机理

采用稍不平行电极进行大气压He气介质阻挡多脉冲辉光放电实验,通过增强电子耦合器件相机短时曝光照片,研究大气压多脉冲辉光放电在不同时刻的放电模式.通过气隙放电电流、表面电荷计算,理论分析了表面电荷、空间电荷、外加电压与气隙电场强度的关系,研究大气压辉光放电形成多脉冲的机理.实验结果表明,放电首先在间隙稍窄的电极左端开始;在第一个脉冲电流峰值,电极右端也开始放电;第一个电流脉冲经历了Townsend放电到辉光放电的过程;电流脉冲之间的时间内,间隙一直维持着微弱的辉光放电;随后的每个电流脉冲均是辉光放电.理论分析表明,大气压辉光放电的多个电流脉冲是表面电荷、空间电荷与外加电压共同演化的结果;除放电伊始出现Townsend放电外,同一半周期内的放电电流脉冲中不会再出现Townsend放电. 关键词： 介质阻挡放电 增强电子耦合器件 大气压辉光放电 多脉冲     

Significantly improved charge stability of cellular polypropylene films by fluorination and subsequent annealing

An extremely effective and practical approach is proposed and used for improving charge stability of cellular polypropylene (PP) films. The approach is composed of fluorination and subsequent annealing of the PP films. Surface charge stability is significantly improved by the approach, as revealed by the measurements of open-circuit thermally stimulated discharge (TSD) current, charge TSD and isothermal charge decay at 90 °C. As an example, after 7 h at 90 °C, the amount of surface charge of the treated PP film by the approach still remains about 72% of its initial value, while the corresponding value is only 27% for the virgin PP film. The improvement of charge stability is attributed to chemical composition change and structure modification of the PP films due to the fluorination and annealing treatments, as indicated by attenuated total reflection infrared analyses and wide angle X-ray diffraction measurements. The treatments eliminate the shallow charge traps almost completely and produce much deeper ones.