Ionization‐Facilitated Formation of 2D (Alumino)Silicate–Noble Gas Clathrate Compounds

The nanoscale confinement of noble gases at noncryogenic temperatures is crucial for many applications including noble gas separations, nuclear waste remediation, and the removal of radon. However, this process is extremely difficult primarily due to the weak trapping forces of the host matrices upon noble gas physisorption. Herein, the formation of 2D clathrate compounds, which result from trapping noble gas atoms (Ar, Kr, and Xe) inside nanocages of ultrathin silica and aluminosilicate crystalline nanoporous frameworks at 300 K, is reported. The formation of the 2D clathrate compounds is attributed to a novel activated physisorption mechanism, facilitated by ionization of noble gas atoms. Combined X‐ray photoelectron spectroscopy (XPS) and density functional theory (DFT) studies provide evidence of an initial ionization process that significantly reduces the apparent trapping barrier. Noble gas ions become neutralized upon entering the cages, and their desorption requires unprecedentedly high temperatures, even in ultrahigh vacuum conditions. From 2D aluminosilicate films these temperatures are 348 K (Ar), 498 K (Kr), and 673 K (Xe). DFT calculations also predict that Rn can be trapped in 2D aluminosilicates with an even higher desorption temperature of 775 K. This work highlights a new ionization‐facilitated trapping mechanism resulting in the thinnest family of clathrates ever reported.     

SrCaO Protective Layer for High-Efficiency PDPs

The sustain pulse voltage of the panel for 66-kPa Ne + Xe (5%-30%) is 20%-40% lower with a Sr_0.62Ca_0.38O protective layer than with a MgO protective layer. At a normal sustain voltage of 160-200 V, the luminous efficiency of the panel with the Sr_0.62 Ca_0.38O protective layer for Xe (30%) is about twice as high as with the MgO protective layer for Xe (10%). The luminances of these panels are almost the same. This high efficiency at normal sustain pulse voltage and normal luminance is obtained through the combined use of the Sr_0.62Ca_0.38O protective layer and high Xe content. With regard to ion bombardment, the Sr_0.62Ca_0.38O film has a 4.5 times longer life than SrO film and nearly 80% of the life of MgO film. We also calculated the values of theoretical secondary electron emission yield gamma_imin of MgO, SrO, and CaO without energy bands in the band gap for rare gas ions and found that [ gamma_imin of MgO] les [gamma_imin of CaO] < [gamma_imin of SrO] except for the one case with He. The breakdown voltage decreases with higher gamma_imin values. As expected, the discharge voltage of the panel is much lower with the SrO protective layer than with the MgO protective layer. The discharge voltages of the panels with Sr_0.62Ca_0.38O and SrO protective layers are almost the same. These findings show that the life of the SrO protective layer can be made 4.5 times longer without any increase in the discharge voltage by adding CaO (40 at.%)     

拓扑绝缘体光电探测器研究进展

由于拓扑绝缘体具有优异的光学和电学特性以及特殊的能带结构,使其在发展高性能的宽光谱光电探测器方面具有巨大的前景。然而由于拓扑绝缘体的发现较晚,其在光电探测器领域的研究还处于初始阶段。因而存在许多亟待解决的问题,如制备更高质量的拓扑绝缘体材料。本综述概述了拓扑绝缘体材料的发展历程,并从材料制备和材料体系的角度阐述了基于拓扑绝缘体材料的光电探测器的研究进展,并展望了拓扑绝缘体材料在光电探测器领域的发展前景。     

EXPERIMENTAL RESEARCH OF ELECTRO-OPTICAL CHARACTERISTICS OF NOBLE GASES IN AC PLASMA DISPLAY PANEL

Luminous spectra and electric characteristics of gas mixtures:Ar+He,Kr+He,He+Ne,He+Xe,Kr+Ar and Ar+Hg are investigated in order to find out a kind of gas mixture radiatingblue-green light.It was shown in the investigation that the gas mixture of Ar+Hg,which radiates blue-greenlight,and has higher brightness and lower firing voltage,is more satisfactory.     

交流等离子体显示板中惰性气体放电的电光特性实验研究

为了寻求一种供等离子体显示板用的发蓝绿光的混合气体,本文对Ar+He、Kr+He、He+Ne、He+Xe、Kr+Ar和Ar+Hg混合气体的发光光谱和电特性进行了研究。发现混合气体Ar+Hg较为满意,发光颜色为蓝绿色、亮度较高、着火电压较低。     

Hole current in dual dielectric under positive gate voltage

n-channel dual-dielectric transistors with SiO2:Si3N4gate insulators were fabricated with and without boron implant in the channel. Under positive gate voltage stress, electrons can enter the insulator from the silicon, and holes can enter the silicon from the insulator. The electrons and holes were measured by the technique described by Ginovker et al.[1]. For oxides thicker than 30 Å, it is always observed that the silicon hole current is 3-4 orders of magnitude below the silicon electron current. The physical origin of this hole current is shown to be field-enhanced excitation of electrons from the valence band to the conduction band in the silicon prior to entering the insulator, and is not due to the holes from the insulator entering the silicon.     

形成KrⅡ469.5nm激光振荡的动力学过程

用自吸法测试了不同放电条件下在He-Kr空心阴极放电的余辉阶段中Hem(2s3S1)态布居密度随时间的变化.进而计算了这一亚稳态原子和氪基态原子彭宁电离速率常数,从而更深入地讨论了这一激光振荡的激励机制.     

基于紫外图谱的盘式绝缘子放电强度径向分布研究

为研究盘式绝缘子积污放电的紫外图谱特征,提出了一种基于图像分割的光斑面积计算方法。首先,基于C-V模型,开展积污绝缘子紫外图像径向分布的研究。接着,与红外温度场曲线进行对比研究,验证其合理性。最后,研究不同电阻率、风速情况下积污绝缘子的紫外图谱特征。研究结果表明：C-V模型应用于图像处理中,具有较强的抗干扰性,适用于盘式绝缘子径向放电强度的研究;随着表面电阻率的降低,盘式绝缘子紫外光斑面积会增大;风速对盘式绝缘子放电强度有明显的影响;研究结果可为盘式绝缘子径向放电强度的评估提供一定的参考。     

航拍图像中玻璃绝缘子自爆缺陷的检测及定位

在分析输电线路无人机巡检系统航拍图像中绝缘子及其自爆缺陷特征的基础上,提出一种玻璃绝缘子自爆缺陷的检测及定位方法。该方法首先在色调、色饱和度、亮度(HSI)颜色空间分别对 H(Hue)和 S(Saturation)分量运用最大类间方差法(OTSU)分割图像,获取绝缘子前景连通域;之后,运用直方图方法对检测到的前景轮廓的倾角和面积分布进行统计,准确识别绝缘子轮廓;最后,设计了一种特征检测算法,检测并标记自爆绝缘子位置。实验证明该方法能从自然背景中准确检测并定位绝缘子自爆缺陷,具有较好的工程应用价值。     

Quasi-stationary electron and ion processes in dielectric films and diagnostics of films

The principle of quasi-equilibrium in the study of the structures that contain semiconductors and insulators, in particular, dielectric films in the metal-insulator-semiconductor (MIS) structures is discussed. A possibility of the simultaneous measurements of the averaged convection currents in an insulator and the current flows through the semiconductor-insulator interface in the MIS structures is considered. The methods for the measurement of the concentration of mobile ions in a dielectric film are analyzed.     

大尺寸改性聚苯醚绝缘垫片注塑工艺的研究

介绍了一种压缩气体绝缘传输线(CGIT)用大尺寸改性聚苯醚(MPPO)绝缘垫片的注塑成型工艺。该绝缘垫片厚度为26mm,外径为240mm,根据该尺寸设计了注塑成型模具,并通过超声波无损探伤技术对绝缘垫片内部缺陷进行了检测,结果表明绝缘垫片内部缺陷普遍存在于厚度12mm处。因此,对注塑模具和工艺参数采取了改进措施,如增加模具排气孔,增大浇口、流道和喷嘴的尺寸,调整熔融温度、射胶速度、注射压力和保压时间等。工艺改进后,绝缘垫片试样经逐层解剖,内部无肉眼可见缺陷。     

基于红外图像的零值绝缘子自动检测算法

在电力系统中,利用计算机视觉和图像处理技术对零值绝缘子进行检测,对保障电力系统的安全运行具有非常重要的作用。提出了一种基于红外图像的零值绝缘子自动检测算法。该算法首先对输入图像进行预处理,利用GLOH描述子结合机器学习精确定位绝缘子,然后利用图谱方法提取图像的边界点,并搜索初始轮廓线作为初始值,利用GVF Snake模型检测绝缘子串的精确轮廓线,以分割绝缘子,最后通过分析统计直方图,实现零值绝缘子的自动检测。实验结果表明,所提出的算法可以有效地检测零值绝缘子。     

Conductivity switching effect in MIS structures with silicon-based insulators, fabricated by low-frequency plasma-enhanced chemical vapor deposition methods

The current-voltage characteristics of MIS (metal-insulator-semiconductor) structures with insulators based on silicon oxide, fabricated by low-frequency (55 kHz) plasma-enhanced chemical vapor deposition are studied. A specific feature of the used insulators is that there are inclusions of particles of other materials with narrower band gaps present. It is found that such structures possess the property of bipolar conductivity switching. The MIS structures with a multilayer insulator containing additional nanoscale siliconnitride layers exhibit the best characteristics of the conductivity switching effect.     

Multiple Quantum States Induced in 1T-TaSe2 by Controlling the Stacking Order of Charge Density Waves

Van der Waals (vdW) materials afford unprecedented opportunities for control of electronic properties by utilizing the stacking degree of freedom. An intriguing frontier, largely unexplored, is the stacking of charge density wave (CDW) phases that is a broken-symmetry state with periodically modulated charge density and the atomic lattice. Employing density functional theory, it is uncovered that the stacking order can play a significant role in the quantum phase transitions of layered 1T-TaSe₂ with a striking 2D CDW order. By controlling the vertical stacking order of CDWs, bulk 1T-TaSe₂ can host various electronic phases including quasi-1D and 3D metals and band insulators. Particularly, the ground-state stacking configuration shows 3D metallicity due to the enhanced intralayer and interlayer electron hopping, and the second lowest energy configuration shows band insulating behavior via interlayer dimerization, implying potential metal-insulator transition. In ultrathin-layer 1T-TaSe₂, not only the stacking order but also the thickness dictate the electronic properties. While the monolayer is a Mott insulator, the bilayer (trilayer) is a band insulator (metal). More interestingly, the four-layer emerges as an insulator or a semimetal dependent on its stacking order. The wide-tunable electronic properties of 1T-TaSe₂ CDW compound will open a new pathway for designing novel quantum devices.     

Scaling characteristics of the XeF (C→A)excimer laser

The scaling characteristics and medium properties of an injection-controlled XeF(C→A) laser pumped by a 10-ns-high current density electron beam have been investigated. A five-component laser gas mixture, consisting of F₂, NF₃ , Xe, Kr, and Ar was optimized for the scaled laser conditions, resulting in 0.8-J output pulses at 486.8 nm, corresponding to an energy density of small-signal-gain measurements combined with kinetic modeling permitted the characteristics of the dependence of net gain on the electron-beam energy deposition and gas mixture composition, resulting in an improved understanding of XeF(C→A) laser operation     

Features of carrier tunneling between the silicon valence band and metal in devices based on the Al/high-<Emphasis Type="Italic">K</Emphasis> oxide/SiO<Subscript>2</Subscript>/Si structure

The features of electron tunneling from or into the silicon valence band in a metal–insulator–semiconductor system with the HfO₂(ZrO₂)/SiO₂ double-layer insulator are theoretically analyzed for different modes. It is demonstrated that the valence-band current plays a less important role in structures with HfO₂(ZrO₂)/SiO₂ than in structures containing only silicon dioxide. In the case of a very wide-gap high-K oxide ZrO₂, nonmonotonic behavior related to tunneling through the upper barrier is predicted for the valence-band–metal current component. The use of an insulator stack can offer certain advantages for some devices, including diodes, bipolar tunnel-emitter transistors, and resonant-tunneling diodes, along with the traditional use of high-K insulators in a field-effect transistor.     

Ultraviolet ion laser performance and spectroscopy--Part I: New strong noble-gas transitions below 2500 Å

The performance and spectroscopy of UV ion lasers have been investigated to 1850 Å, the limit of available mirrors. New anomalously strong transitions of about 1-kW peak power were found in Xe IV? at 2315.357 Å and Kr IV at 2191.916 Å. The shortest wavelength new laser transition was Kr IV at 1949.623 Å. Wavelengths were measured for 25 new and many previously known UV laser transitions to about 0.006 Å. Optimum output in watts was also measured as a function of bore current density and gas pressure. All measurements were taken from a 7-mm-bore 150-cm-arc-length tube designed for low electrical inductance providing current excitation pulses with 250-ns full width at half maximum (FWHM).     

MOPA脉冲光纤激光清洗电力绝缘子的工艺探索

为了满足多种材质的绝缘子系统应用, 采用自主研发的能量达2mJ的主振荡功率放大器脉冲光纤激光器进行了激光清洗实验。分别进行了玻璃、陶瓷及硅橡胶绝缘子的激光清洗实验验证, 取得了各自的最佳清洗激光参数, 同时分析绝缘子清洗速率、激光脉冲参数与清洗效果的关系。结果表明, 在最高10m/s的激光扫描速率下, 可取得3.4cm2/s的清洗效率, 该激光系统可高效地用于多种材料表面清洁。这一结果对电力绝缘子激光清洗应用提供了重要的参考意义。     

基于GWO-SVM的红外热成像低零值绝缘子识别

为了准确识别电网中的低零值绝缘子,提高劣化绝缘子诊断的准确率,提出了一种使用灰狼算法优化（grey wolf optimizer, GWO）与二进制支持向量机（support vector machine, SVM）分类器相结合的模型,对红外图像中的低零值绝缘子进行自动检测。首先对绝缘子红外图像进行增强,利用Ostu算法对红外图像进行分割,并对得到的二值图像进行倾斜角度矫正和切割,提取绝缘子串的有效区域,然后将图像特征用于向量机的分类识别。实验结果表明,灰狼算法优化支持向量机比常用的网格搜索算法（grid search, GS）、粒子群优化算法（particle swarm optimization, PSO）等得到的分类模型能更准确、有效地对低零值绝缘子进行识别,且准确率更高。     

Comparison of Kr and Xe flashlamps for Nd:YAG lasers

Linear krypton and xenon flashlamps (6-mm bore, 3-inch arc) having various fill pressures between 450 torr and 4 atm have been operated in a single elliptical gold-plated pump cavity to excite a Nd:YAG laser rod (0.25-inch diameter, 3 inches long). Here we describe laser operation as a function of lamp fill, for electrical input energies ranging from 2 to 40 joules (120-μs pulse duration) and for pulse repetition rates from single shot to 20 Hz. We have found that Kr lamps are generally superior to Xe lamps for pumping Nd: YAG except at high current densities. Specifically, for this system (the parameters of which are suitable for commercial and military applications), the optimum Kr fill pressure is approximately 700 torr, while the optimum Xe fill pressure is roughly 1000 torr. The threshold with the 700-tort Kr lamp is 58 percent of that with the 1000-torr Xe lamp; the crossover energy (for equal absolute efficiencies) is 40-joule input, which in our system corresponds to about 375-mJ output.