Stability and Dynamics of Mesoscale Microstructure

9633719 Chen将对相变和材料加工过程中介观微观结构的稳定性和动态演化进行理论研究。 主要目标是开发一个统一的模型，可以有效地用于研究不仅在单晶中具有竞争的短程和长程相互作用的多畴结构，而且在技术感兴趣的陶瓷材料中的多晶粒和多相微观结构。 一个连续场的方法和三个具体的问题将被调查：域的形成和动力学在铁电氧化物作为竞争的静电能，弹性能和畴壁能量的结果;纳米级有序域的形成在弛豫铁电体;和，动力学的微结构演变的多晶粒材料驱动的减少在总的界面能。 该补助金研究材料研究中具有关键技术影响的重要基础问题。 也就是说，分析和数值方法将被用来研究和理解材料中的微观结构的演变，因为它们通过相变。 这是一个非常困难的基本问题，直接影响材料加工。 要研究的特定系统是陶瓷材料，其中微观结构的控制对材料性能有直接影响。 在这项研究中特别感兴趣的将是铁电材料，其可用作传感器和光学元件。 ***

9633719 Chen Theoretical studies will be made of the stability and dynamic evolution of mesoscopic microstructures during phase transformations and materials processing. The main objective is to develop a unified model which can efficiently be employed to study not only the multi-domain structures with competing short- and long-range interactions in a single crystal, but also the multi-grain and multi- phase microstructures in ceramic materials of technological interest. A continuum field approach is used and three specific problems will be investigated: domain formation and dynamics in ferroelectric oxides as a result of competing electrostatic energy, elastic energy and domain wall energy; the formation of nanoscale ordered domains in relaxor ferroelectrics; and, the kinetics of microstructural evolution in multi-grain materials driven by the reduction in the total interfacial energy. %%% This grant studies an important fundamental problem in materials research which has critical technological implications. Namely, analytical and numerical methods will be used to study and understand the evolution of microstructure in materials as they go through changes in phase. This is an extremely difficult fundamental problem which directly impacts materials processing. The particular systems to be studied are ceramic materials in which control of the microstructure has direct bearing on material proerties. Of special interest in this research will be ferroelectric materials which have applications as sensors and optical components. ***