1972年第1卷至1982年第11卷《物理》分类目录索引(续)

题 目 卷 年 页 电介质、快离子导体高压陶瓷变压器 2(1973)183压电陶瓷的高温极化 3(1974)268驻极体及其应用 5(1977)287反铁电陶瓷的研究和应用 7(197)163核磁共振在铁电相变研究中的应用 7(1978)217多晶β氧化铝固体电介质的电导及激活 能的测定 9(1980)1超离子导体 9(1980) 135铁电体低频电滞同线的测量 9(1980)207PLZT电光开关特性及其应用 9(1980)264铁电体介电常数和热电系数的测量 9(1980) 407电介质的热噪声 9(1980)486离子导体薄膜 9(1980)518氧离子导体离子迁移数的测量与温差电势10(1981)222快离子导体的核磁共振研究 10(1981…     

铁电材料与铁电物理的进展

自从1920年发现了酒石酸钾钠(罗息盐)的铁电性以来,迄今巳发现了超过一千种铁电体,其中一些已经对经济和技术的发展起到积极的作用[1].铁电体具有自发极化,而且在外加应力、电场(电磁波)或温度改变时,其自发极化大小也相应地变化,因此铁电体可以表现出具有力、声、光、热、电等交互响应的物理效应,从而成为高技术领域中制造多功能器件以及敏感元件的理想材料之一. 从铁电体研究的发展历程看,铁电体研究的特点有:(1)基础研究与固体物理发展密切相关.例如,铁电体相转变理论的研究正是从推广朗道的现代相变理论开始的,现今的重整化群理论也用来…     

激光-等离子体相互作用过程中离子发射的各向异性

用波长为1.06μm、强度为10~(12)～10~( 14)W/cm~2的激光辐照金属平面靶,在点状聚焦和线状聚焦方式下,离子发射速度及其动量呈现各向异性;通过分析低Z靶和高Z靶在不同能量的激光照射下的离子发射速度V_p和消融质量M,研究离子发射的定标规律.     

铁电体阴极的发射性能

研究了不同铁电体阴极样品的发射行为表明在同样激励条件下，不同材料的铁电样品发射电流密度有显著差别，在集电极接地情况下，ＰＬＺＴ２／９５／５陶瓷测得的最大发射电流密度为３５Ａ／ｃｍ＿２，透明的ＬｉＮｂＯ＿３单晶为３８Ａ／ｃｍ＿２。样品的击穿阈值是极化难以达到完全翻转的主要障碍。分析了阴极表面金属栅的存在对铁电体发射的不利影响，“Ｅ⊥Ｐ”激励模式是克服这些困难的一个新途径。对两种最近试制的材料作了发射试验，观测到的最大发射电流密度超过了１００Ａ／ｃｍ￣２，估算该发射束的归一化均方根发射度为１０￣（－６）ｍ·ｒａｄ和归一化峰值亮度为１０￣（１２）Ａ／ｍ￣２·ｒａｄ￣２量级。     

芳羧酸功能化的聚苯乙烯与Tb(Ⅲ)离子形成的 高分子-稀土配合物的荧光发射性能

通过大分子反应将苯甲酸(BA)键合在聚苯乙烯(PS)侧链, 制得芳羧酸功能化的聚苯乙烯PSBA。以PSBA为大分子配基, 以邻菲啰啉(Phen)为小分子配体, 与Tb(Ⅲ)离子配位, 分别制备了二元配合物PS-(BA)₃-Tb(Ⅲ)与三元配合物PS-(BA)₁-Tb(Ⅲ)-(Phen)₂及PS-(BA)₁-Tb(Ⅲ)-(Phen)₃,采用红外光谱(FTIR)和紫外吸收光谱(UV) 对配合物进行了表征, 深入研究了配合物(溶液与薄膜)的荧光发射性能。 研究结果表明, 大分子配基PSBA与Tb(Ⅲ)离子所形成的二元或三元高分子-稀土配合物均能发射出很强的Tb(Ⅲ)离子特征荧光, 即键合在PSBA侧链的配基BA能有效地敏化Tb(Ⅲ)离子的荧光发射。与二元配合物相比较, 以小分子Phen为第二配体所形成的两种三元配合物具有强度更高的荧光发射。     

近玻尔速度Ne2+离子穿过碳膜引起的电子发射

本文测量了入射能为2–25 keV/u的Ne²⁺离子穿过不同厚度碳膜诱导的前向、后向 (分别对应出射表面和入射表面) 电子发射产额. 实验中通过改变炮弹离子的能量, 系统的研究了势能沉积、电子能损以及反冲原子对前向、后向电子发射产额的贡献. 结果表明, 离子的势能沉积只对后向电子发射有贡献, 前向、后向电子发射产额分别与Ne²⁺离子在薄膜出射、入射表面的电子能损近似成正比关系, 其中电子能损很低 (对应于离子能量很低) 的时候, 反冲原子对电子发射的贡献不能忽略. 关键词： 近玻尔速度 电子发射 电子能损 反冲原子     

铁电体阴极的实验研究

铁电体阴极是一种具有很大发展潜力的新型高亮度、高重复率、强流电子束源。电子发射的基本机制是利用铁电体中的快极化反转产生的极化值变化,其转换时间为纳秒量级,因此,重复率可达数百兆赫;最大电子发射密度为10~(14)/cm~2;发射电流的大小取决于样品上激励电压的上升时间;发射电子的最大能量决定于样品厚度,初步估算,在电流强度相同的情况下,铁电阴极的亮度可比激光照射的光阴极高4倍,与传统电子源相比,它具备许多特殊的优点,本文报导了E∥P和E⊥P两种实验模式,测得的最大发射电流密度分别为12A/cm~2和21A/cm~2。     

反铁电陶瓷的强电子发射特性研究

采用掺镧锆锡钛酸铅反铁电陶瓷作为阴极材料,研究了脉冲电压激励下陶瓷的电子发射特性.当激励电压为800V、抽取电压为0V时,得到1.27A/cm²的发射电流密度;当抽取电压增加到4kV时,获得1700A/cm²的发射电流密度.分析了发射电流随抽取电压的变化关系,讨论了反铁电陶瓷强电子发射的内在机理.结果表明：掺镧锆锡钛酸铅反铁电陶瓷能够在较低的激励电压(400V)下实现电子发射,发射电流远大于按照Child-Langmuir定律计算出的电流,三接点附近局域反铁电—铁电相变产生初始电子发射,初始电子电离中性粒子形成等离子体,增强了电子发射. 关键词： 铁电阴极 反铁电体 电子发射     

萘甲酸功能化的聚苯乙烯与Eu(Ⅲ)离子所形成的高分子-稀土配合物的荧光发射特性

通过大分子反应将萘甲酸(NA)键合在聚苯乙烯(PS)侧链, 制得萘甲酸功能化的聚苯乙烯PSNA。 以PSNA为大分子配基, 以邻菲罗啉(Phen)为小分子配体, 与Eu(Ⅲ)离子配位, 分别制备了高分子-稀土二元发光配合物PS-(NA)₃-Eu(Ⅲ)与高分子-稀土三元发光配合物PS-(NA)₃-Eu(Ⅲ)-Phen。 采用红外光谱(FTIR)和紫外吸收光(UV)谱对配合物进行了表征, 深入研究了配合物的化学结构与发光性能的关系, 并应用Antenna效应理论, 从微观机理上进行了深入分析。 制备了配合物的固体薄膜, 考察了固体薄膜的荧光发射性能。 研究结果表明, 大分子配基PSNA与Eu(Ⅲ)离子所形成的二元或三元高分子-稀土配合物, 均能发射出很强的Eu(Ⅲ)离子的特征荧光, 即键合在PSNA侧链的配基NA能有效地敏化Eu(Ⅲ)离子的荧光发射。 大分子侧链的萘甲酸配基比苯甲酸配基对Eu(Ⅲ)离子荧光发射具有更强的敏化作用。 第二配体的协同配位效应导致三元配合物的荧光发射强度高于二元配合物。     

（EUxRE1-x）（FTFA）3Phen配合物的合成、表征及荧光性能

在无水乙醇溶液中用氯化稀土与4,4,4-三氟-1-(2-呋喃基)-1,3-丁二酮(FTFA)和邻菲啰啉(Phen)反应,合成了标题配合物;对其进行了元素分析、摩尔电导、红外光谱分析及荧光性能的研究。结果表明其化学组成分别为Eu(FTFA)3Phen、Sm(FTFA)3Phen;(Eu0.5RE0.5)(FTFA)3Phen(RE=Y,La和Gd)及(EuxGd1-x)(FTFA)3Phen(x=0.1,0.3,0.4,0.7,0.9)。配体FTFA通过烯醇式氧负离子与稀土离子双齿螯合配位,Phen的两个氮原子与稀土离子呈环状配位;所有配合物均为非电解质。光谱实验结果表明,铕配合物的荧光发射强度要远大于钐配合物的荧光强度;对于铕系列掺杂配合物来讲,所有激发光谱都为一宽带峰,表明配体能很好的吸收能量;在荧光惰性Gd3 离子的含量0.1相似文献   

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Characteristics of ion emission from the ferroelectric media was investigated under low pressure condition. By utilizing high-speed camera photography, spectral analysis, and particle-in-cell simulation coupling with Monte Carlo collision, the optical emission composition and images from ferroelectric surface, plasma evolution of ferroelectric surface discharge, the mechanism of ion generation and the forming of ion current are discussed. These results are useful for further understanding to ferroelectric ion sources.     

Photoluminescence properties of porous InP filled with ferroelectric polymers

Photoluminescence properties of porous InP are found to be strongly affected by infilling ferroelectric polymers. Based on the temperature- and excitation-power-dependent photoluminescence, the intensity suppression and blue shift of the near-band-edge emission are supposed to result from the passivation of surface states by introducing ferroelectric polymers. On the other hand, the significant enhancement of deep-level emission is caused by the increased concentration of phosphorus vacancies due to ion exchange when infilling the ferroelectric polymers into porous InP. The surface passivation of porous InP by ferroelectric polymers is useful for improving the performances of InP-based electronic and optoelectronic devices.     

Coulomb microexplosions of ferroelectric ceramics

Energetic neutral and extreme ultraviolet emission initiated by the dense plasma propagation along a ferroelectric surface has been found. It was shown that the emission of neutrals is characterized by a large divergence and velocities up to 7 x 10(7) cm/s. This phenomenon is explained by an extremely large electric field with amplitude > or =10(6) V/cm and rise time approximately 10(-10) s which appears at the plasma front due to the fast fall in the driving pulse. This electric field causes microexplosions of the ferroelectric surface due to inertia in the ion polarization response.     

Potential relief on the surface of polarized ferroelectric electrets from an analysis of the anomalous electron emission spectra

A technique is proposed for determining the specific features in the potential distribution over a free surface of polarized ferroelectric electrets from analyzing the anomalous electron emission spectra. This technique is applied to examine the potential distribution over the surface of a lead magnoniobate single crystal and ferroelectric ceramics. Reasoning from the results obtained for the lead magnoniobate crystal, the inference is drawn that the degree of perfection of surface layers of ferroelectric single crystals can be controlled using the anomalous electron emission spectra.     

Energetic electron emission from a ferroelectric sample during incomplete surface discharge

In this paper, the results of simplified analytical modeling and particle-in-cell numerical simulations of plasma formation and propagation along the surface of a ferroelectric sample under the application of a negative driving pulse to the rear solid electrode are presented. These models allow one to reproduce the main characteristics of the incomplete discharge. In particular, it is shown that the experimentally observed energetic electrons are related to the secondary emission electron acceleration in the sheath between the plasma and the ferroelectric surface. Also, simulation results show that secondary electron emission significantly decreases the surface plasma density while increasing its propagation velocity and that high desorption rate of the neutrals is required to sustain surface plasma formation.     

Electron emission from charged surfaces of ferroelectrics-electrets: Part 1. Properties of the electron emission

The present paper describes properties of the electron emission from negatively charged surfaces of poled ferroelectrics-electrets. This emission results from the irradiation of the surface with X-rays of weak intensity. It has been shown both experimentally and theoretically that the mechanism of its emergence differs from the photoemission mechanism, it rather roots in the ferroelectric state of the surface layer.     

掺镧锆锡钛酸铅陶瓷极化强度变化量对电子发射电流强度的影响

铁电阴极因其优异的电子发射性能在高功率微波管的电子束源、平板显示技术以及宇航推进器等领域 有着广阔应用前景而日益受到人们的重视.大量研究表明,铁电阴极电子发射性能受阴极材料性能的影响. 在激励电场作用下,铁电阴极材料会产生表面非屏蔽电荷而引起极化强度的变化, 这表明铁电阴极电子发射性能可能与阴极材料的极化强度变化量存在着某种关系. 为研究阴极材料极化强度变化量对铁电阴极电子发射性能的影响,以掺镧锆锡钛酸铅铁电和反铁电陶瓷样品 作为阴极材料,通过正半周电滞回线测试得到阴极材料在不同电场强度下的极化强度变化量, 测量得到电子发射电流强度随激励电场的变化曲线,并分析了电子发射电流强度与极化强度变化量的关系. 结果表明,两种样品电子发射电流强度与极化强度变化量正相关.     

Thermostimulated electron emission from polar cleavage of a triglycine sulfate crystal

This paper reports the results of experimental investigations into thermostimulated electron emission from the positive and negative cleavage surfaces of a ferroelectric triglycine sulfate crystal. It is shown that the current density j of emission from the negative surface is universally higher than that from the positive surface over the entire range from room temperature to the Curie point. The shape of the j(T) curves substantially depends on the degree of natural unipolarity of the studied samples. The results obtained are discussed in the framework of the mechanism of field electron emission from the surface electronic states.     

Low-voltage pulse exciting electron emission from ferroelectric copolymer film cathode: Role of film thickness and emission stability

Ferroelectric copolymer thin films P(VDF-TrFE) are used as a ferroelectric cathode for investigation of their electron emission properties. This ferroelectric copolymer films with different thicknesses are deposited by spin-coating method, and then the annealing process is carried out to improve the crystallinities of as-deposited copolymer films. The measurement results of ferroelectric electron emission showed that the copolymer P(VDF-TrFE) films had a desired ferroelectric electron emission ability excited at low-voltage pulse, and its peak emission current can reach to be ∼1.3 μA when the pulse voltage is 280 V. In addition, the effect of film thickness on electron emission property and emission stability of copolymer thin film P(VDF-TrFE) are discussed.     

Mechanism of negative ion emission from surfaces of ferroelectrics

Experimental studies of the mechanism of negative ion and cluster ion emission from surfaces of ferroelectrics are described. The emission was produced by negative voltage pulses with the amplitude of about 400 V, with a rapid rise-time (below 10 ns) and a slow decay‐time (several μs). The pulses were applied between the back side of the ferroelectric sample and the metal tip touching the front emitting side. The surface of the ferroelectrics could be cleaned in situ by 1 keV Ar⁺ bombardment. The morphologic changes around the tip were observed with an atomic force microscope (AFM). Mostly negative ions and cluster ions were emitted and studied in our experiments. Positive ions were detected with much lower probability and are produced by an entirely different microscopic process than negative ions. Masses as well as energies of emitted ions were measured with a time-of-flight (TOF) spectrometer and compared with available spontaneous desorption (SD) spectra and Cs‐SIMS spectra in order to clarify the mechanism of the emission. The trajectory of ions emitted from the sample was studied by computer simulation. The conclusion of these studies is that the negative ion emission is caused by the Coulomb explosion of a polarization cloud rapidly formed at the front edge of the pulse. The explosion takes place in the vicinity of the tip-sample contact at distances several tens of μm from the contact where the stabilizing effect of the positively charged tip is already small.