Computation of relaxational dielectric polarization of composites

复合材料弛豫介电极化的计算

• 批准号: 317673443
• 负责人: Professor Dr.-Ing. Herbert Kliem
• 金额: --
• 依托单位: Lehrstuhl für Grundlagen und Materialien der Elektrotechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/317673443?language=en
• 关键词: Computation; relaxational; dielectric; polarization; composites

Effective relaxational polarizations of dielectric composite materials are computed with a microscopic model based on the electrostatic interactions between charges and dipoles as well as based on the Boltzmann statistics. Input parameters of the simulations are the material structure, the polarizabilities of the atoms and molecules with induced dipole moment and the activation energies for charges which fluctuate thermally activated in double well potentials. The fluctuating charges yield the relaxational part of the polarization. The high frequency behavior of the system is determined by the induced dipoles. With iterative algorithms, the fields at the locations of all dipoles and double well potentials are calculated with respect to the fields of all charges and dipoles in the material. The electrodes are taken into account via the method of images for dipoles and charges. With the local fields the induced dipole moments are computed. The charge displacements in double well potentials are calculated using a dynamic Monte-Carlo method regarding the local fields. In this way the method inherently includes all interactions and all depolarizing fields within the material. Particularly with regard to composite materials, the topology, interfaces and the interaction between different phases are considered. We investigate single phase dielectrics and dielectric composites with different interior geometries. The composites are composed of interacting phases which can differ in their relaxational polarization behavior and in their high frequency responses. As the result we calculate polarization responses in the time domain on steps of the applied field and on oscillating applied fields. Frequency dependent complex permittivities are computed from the time domain polarization via Fourier transformation. They are compared to the results obtained by the calculation using oscillating fields. Furthermore the impact of a temperature gradient in a dielectric on its polarization is simulated.

基于电荷与偶极子之间的静电相互作用和玻尔兹曼统计，用微观模型计算了介电复合材料的有效弛豫极化。模拟的输入参数是材料结构、具有诱导偶极矩的原子和分子的极化率以及在双势垒势中波动热激活的电荷的活化能。波动的电荷产生极化的弛豫部分。系统的高频行为由诱导偶极子决定。用迭代算法计算了材料中所有电荷场和偶极子场在所有偶极子和双势的位置处的场。通过偶极子和电荷的成像法考虑了电极。利用局域场计算了感应偶极矩。用关于局域场的动态蒙特卡罗方法计算了双势垒势中的电荷位移。以这种方式，该方法固有地包括材料内的所有相互作用和所有去极化场。特别是对于复合材料，考虑了材料的拓扑结构、界面以及不同相之间的相互作用。我们研究了具有不同内部几何结构的单相介质和介电复合材料。复合材料由相互作用的相组成，它们的驰豫极化行为和高频响应可能不同。作为结果，我们在时间域中计算了外场阶跃和振荡外场下的偏振响应。通过傅里叶变换，由时间域偏振态计算出频率相关的复介电常数。将它们与用振荡场计算得到的结果进行了比较。此外，还模拟了介质中温度梯度对其极化的影响。