Computation of relaxational dielectric polarization of composites

基于电荷与偶极子之间的静电相互作用以及玻尔兹曼统计的微观模型，计算了电介质复合材料的有效弛豫极化。模拟的输入参数是材料结构、原子和分子的极化率以及双阱势中热激活的电荷的激活能。涨落的电荷产生极化的弛豫部分。系统的高频特性由感应偶极子决定。利用迭代算法，相对于材料中所有电荷和偶极子的场，计算了所有偶极子和双阱势位置处的场。通过偶极子和电荷的图像的方法考虑电极。利用局部场计算了感应偶极矩。采用考虑局域场的动态蒙特-卡罗方法计算了双势阱中的电荷位移。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，拓扑结构，界面和不同阶段之间的相互作用被认为是。我们研究了具有不同内部几何形状的单相介电复合材料。复合材料由相互作用的相组成，这些相在弛豫极化行为和高频响应方面可以不同。作为结果，我们在时域中计算的极化响应的步骤上的应用领域和振荡的应用领域。频率相关的复介电常数通过傅里叶变换从时域偏振计算。将它们与使用振荡场计算获得的结果进行比较。此外，温度梯度在其极化的电介质的影响进行了模拟。

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.