From Atoms to Continuum: A Multi-scale Multi-Phenomena Theory

从原子到连续统：多尺度多现象理论。乔治华盛顿大学工程与应用科学学院摘要在ABO 3铁电体中，亚纳米尺度的离子位移是压电性和极化重取向的主要原因。宏观陶瓷的晶粒和晶界结构，从纳米到微米尺度，显著地影响机电响应。铁电物理本质上是多尺度的。本研究的目的是提高对多尺度多物理现象的科学认识。我们将从原子晶格动力学出发，通过统计力学、分子动力学模拟和微连续介质模拟，将原子模型与微机电理论联系起来，研究铁电陶瓷的热-电-力耦合响应。这项研究有望通过从原子模型中找到材料参数，为微连续理论向前迈出重要一步。 它将适用于从纳米到宏观的各种长度和时间尺度的问题。如果成功，它将立即在工程上得到应用，包括传感器、执行器、电容器和存储器等。

From Atoms to Continuum: A Multi-Scale Multi-Phenomena TheoryJames D. Lee and Youping ChenSchool of Engineering and Applied ScienceThe George Washington UniversityAbstractIn ABO3 ferroelectrics, the displacements of ions at sub-nanometer scale account for the piezoelectricity and the polarization reorientation. Grain and grain boundary structures, from nano- to micro-scale, of a macroscopic ceramics remarkably influence the electromechanical response. The physics of ferroelectrics is multi-scale in nature. The objective of this research is to enhance the scientific understanding of multi-scale multi-physics phenomena. We will start from atomistic lattice dynamics, through statistical mechanics, molecular dynamics simulations and microcontinuum modeling, to link atomic model to micromorphic electromechanical theory, and to investigate the fully coupled thermo-electro-mechanical response of ferroelectric ceramics. This research is expected to be an important step forward for microcontinuum theories by finding the material parameters from atomistic models. It will be applicable to problems in a wide range of length and time scales from nano- to macroscopic. If successful, it will have immediate engineering applications, including sensors, actuators, capacitors and memory devices, etc.