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基于电介质复折射率的实验数据,采用最小二乘法结合选取的代表频率拟合得到了电介质的介电谱解析表达式,可以得到电介质在全频段的光频常数和介电常数. 研究了三个典型液态电介质,水、乙醇和甲苯的介电谱. 在实验数据可以获取的频率范围内,采用解析表达式得到的光频常数与采用Kramers-Kronig转换得到的折射率实部和实验得到的折射率虚部吻合得很好. 基于介电谱解析表达式可以预测目前实验无法测量的区域的介电谱. 相似文献
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本文介绍了电介质的弛豫研究进展情况和存在的困难.采用对数时间标度,在微分介电谱中,每一种弛豫机构对应一个峰.高分子材料聚丙烯(PP)样品的实验结果表明,多弛豫机构的存在来源于束缚空间电荷的自由扩散 相似文献
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基于电介质-旋电介质的磁表面等离激元(SMPs)模型,从色散方程出发,理论分析了存在表面波时旋电介质介电张量和电介质介电系数的关系,以实现单向传输的SMPs。提出Ce∶YIG/Ag超构旋电材料,根据有效介电张量理论构造满足SMPs条件的旋电介质的介电张量。分析了电介质-旋电介质表面波的色散特性,利用有限元方法对电介质-超构旋电介质模型的传输特性进行了仿真计算,在施加常规磁场(0.2 T)情况下实现了工作于近红外波段的SMPs单向传输,并在该结构中引入缺陷。仿真结果表明该SMPs单向波导具有很好的鲁棒性。 相似文献
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研究了等静压和温度诱导掺镧La的Pb(Zr,Sn,Ti)O3(PLZST)陶瓷材料的铁电反铁电相变、介电压力谱和介电温度谱,研究了温度对压致相变和介电压力谱的影响,结果发现温度使铁电反铁电相变压力降低,介电压力谱具有明显的扩散相变和频率弥散的特点;研究了等静压对介电温度谱的影响,结果表明等静压使铁电反铁电相变温度降低,反铁电顺电相变温度升高.这些现象有利于丰富和拓宽人们对温度和压力诱导的多组元弛豫型铁电体和弛豫型反铁电体扩散相变和弛豫行为的认识和理解.
关键词:
等静压和压致相变
铁电反铁电相变
介电压力谱
介电温度谱 相似文献
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基于界面极化与静电场理论建立了聚醚砜复合超滤膜表面污染层与溶液体系的介电解析模型. 应用参数敏感性分析和介电测量研究了体系中浓差极化层与滤饼层的厚度与电导率对超滤体系介电弛豫的影响机制. 结果表明超滤过程中浓差极化层能快速建立,而滤饼层的形成是一个增长与剥蚀的动态过程;并且浓差极化层与滤饼层的电学性质是影响超滤体系介电谱的关键因素. 比较介电测量与模拟结果证实了建立的超滤体系介电解析模型能够有效可靠地描述与解释超滤体系产生介电驰豫的机制. 相似文献
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采用固相烧结法合成了单相巨介电常数氧化物CaCu3Ti4O12(CCTO).用阻抗分析仪分析了10—420 K温度范围内的介电频谱和阻抗谱特性,并结合ZVIEW软件进行了模拟.结果表明:温度高于室温时,频谱出现两个明显的弛豫台阶,低频弛豫介电常数随温度升高而显著增大,表现出热离子极化特点;温度低于室温时,频谱表现出类德拜弛豫,且高、低平台介电常数值基本不随温度变化,表现出界面极化特点和较好的温度稳定性.频谱中依次出现的介电弛豫对应于阻抗谱中
关键词:
3Ti4O12')" href="#">CaCu3Ti4O12
介电频谱
阻抗谱
Cole-Cole半圆弧 相似文献
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从理论上证明了介电松弛过程在介电谱上等效于电子松弛过程,认为室温下105Hz处特征损耗峰起源于耗尽层处本征缺陷所形成的电子陷阱.在-130—20℃范围内测量了三种配方ZnO陶瓷的介电频谱,发现ZnO压敏陶瓷室温下105Hz处的特征损耗峰在低温下分裂为两个特征峰,认为它们起源于耗尽层中的本征缺陷(锌填隙或/和氧空位)的电子松弛过程.发现ZnO-Bi2O3二元系陶瓷特征峰仅仅由锌填隙引起,而ZnO-Bi2关键词:
ZnO压敏陶瓷
本征缺陷
介电谱
热处理 相似文献
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The dielectric relaxation spectrum of water is calculated from the site-site generalized Langevin/modified mode-coupling theory. The main part of the relaxation follows the Debye-type function, and a small deviation from the Debye relaxation is found on the high-frequency side. This tendency is consistent with recent experiments, although the absolute relaxation time does not agree with the experimental value quantitatively. The time development of the longitudinal polarization function resembles the dielectric part of the memory function, and we consider that this is because the dielectric friction dominates the collective reorientation of the dipole moment of water. We performed calculations with different dielectric constants using the reference interaction-site model integral equation, and found that the large gap between the time scales of the dielectric relaxation and the longitudinal polarization relaxation causes the Debye-type dielectric relaxation in our theory when the dielectric friction is dominant in the friction on the collective reorientation of the dipole moment. Namely, the longitudinal polarization relaxation is fast enough to be considered as a white noise to the dielectric relaxation process, so that the relaxation becomes a Markov process. The large gap between the two relaxation times originates from a large local field correction owing to the large dielectric constant of water. It is also suggested that the deviation from the Debye relaxation at the high-frequency side is the manifestation of the slow memory caused by the long-time part of the longitudinal polarization relaxation in the low-wavenumber region. 相似文献
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The authors' theory of a solvent's influence on heavy particle charge transfer reactions in polar solvents with complex frequency-dependent dielectric constant is applied to treat the dielectric friction on a moving ion. The aim is to demonstrate a relation between the approach used in the theory and other approaches used for treating solute-solvent Coulomb interactions. As a result Zwanzig's formula is recovered. In addition, because this formula is derived by the other method, the relationship between the dielectric friction and the dynamics of nonequilibrium solvent polarization is demonstrated in a very transparent manner. 相似文献
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Due to solvation, excess charge carriers on 1d semiconductor nanostructures immersed in polar solvents undergo self-localization into polaronic states. Using a simplified theoretical model for small-diameter structures, we study low-frequency dynamical properties of resulting 1d adiabatic polarons. The combined microscopic dynamics of the electronic charge density and the solvent leads to macroscopic Langevin dynamics of a polaron and to the appearance of local dielectric relaxation modes. Polaron mobility is evaluated as a function of system parameters. Numerical estimates indicate that the solvated carriers can have mobilities orders of magnitude lower than the intrinsic values. 相似文献
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Influence of polar solvents environment and polymer concentrations on the electrical properties (complex dielectric constant, ac electrical conductivity, complex electric modulus and complex impedance) of the solutions of poly(vinyl pyrrolidone) (PVP) in polar solvents, namely water, ethyl alcohol, ethylene glycol, diethylene glycol, poly(ethylene glycol), glycerol, dimethyl sulfoxide and dimethyl formamide, have been investigated in the frequency range 20 Hz–1 MHz at 25°C. Comparative analysis of the dielectric dispersion curves confirms that the solvent molecular size and number of its hydroxyl groups, and the solutions viscosity, are the major factors which governs the PVP chain segmental motion. The ionic conduction and electrode polarization phenomena has a dominant influence on the large increase of complex dielectric constant values of the solutions of PVP‐polar solvent in the lower frequency region. The values of relaxation times corresponding to these phenomena are also reported. 相似文献
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A. O. Kichigina A. I. Ivanov 《Russian Journal of Physical Chemistry B, Focus on Physics》2012,6(2):175-180
The probabilities of “hot” electronic transitions for inertial (Gauss correlation function) and diffusion (exponential correlation
function) polar solvent relaxation modes were calculated. It was shown that the probabilities of transitions for inertial
and diffusion relaxation could differ by two-three times. The possibility and conditions of the replacement of the inertial
by diffusion relaxation component were studied in the simulation of electronic transition kinetics in real solvents. 相似文献
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Robert Kragler 《Physica A》1982,110(3):373-407
We construct a thermodynamic model for a system of electronic d-bands coupled to the elastic lattice. For the electronic fluctuations a Debye-type of relaxation, for the lattice displacement a modified elastic equation of motion is assumed. As a result a coupling of certain acoustic and relaxational modes is found leading to a soft mode instability. For non-vanishing external fields displacement and dielectric response functions are derived. The special case for wavevector q[110] is worked out explicitly. A comparison between the present phenomenological model and a microscopic multiple-band electron-phonon transport theory, recently given by the author, reveals remarkable agreement between both approaches. 相似文献
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L.V Chebotarev 《Solid State Communications》1983,47(7):549-553
The direct interaction of electrons with impurity field is represented as interelectronic interaction of a special kind which is called “dissipative”. This type of interaction is responsible for relaxation process and generally leads to fluctuations of the relaxation time. The probability distribution function for the mean free time of electrons is found in the white-noise approximation for a one-dimensional conductor. It is shown that the dielectric response function can be obtained in this case by averaging relevant expression over the fluctuations of the relaxation time. 相似文献
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由于CaCu3Ti4O12巨介电常数陶瓷的低频区直流电导较大, 本文采用模量 M"-f频谱表征与分析了低频和高频的两个松弛极化过程. 研究认为, 这两个特征峰属于晶界区Schottky 势垒耗尽层边缘深陷阱的电子松弛过程, 其中高频松弛峰起源于晶粒本征缺陷的电子松弛过程, 而低频松弛峰则为与氧空位有关的松弛极化过程. 对于CaCu3Ti4O12这类低频下具有高直流电导的陶瓷材料, 采用模量频谱能更有效地分析研究其损耗极化机理.
关键词:
3Ti4O12陶瓷')" href="#">CaCu3Ti4O12陶瓷
模量
松弛过程
电导 相似文献