Nanomechanics of Ferroelectric Fractures: Phase-Field Simulations and Piezoresponse Force Microscopy Characterizations

本基金的研究目标是阐明铁电体的断裂，这是一个复杂的过程，涉及纳米尺度下裂纹扩展和铁电畴切换之间的相互作用。一个计算相场方法将被开发来模拟裂纹扩展和域切换在铁电体，和压电响应力显微镜将被应用于在现场观察这种微结构的演变在铁电体下的电，机械和热负荷。这两种技术将结合起来研究各种铁电晶体和陶瓷的断裂行为，从而在与底层物理过程最相关的长度尺度上直接比较计算模拟和微观表征。铁电体是一类重要的技术材料，广泛用作传感器，致动器，电容器和非易失性存储器，并且它们的许多应用依赖于由外场触发的铁电畴转换。铁电断裂过程与铁电畴变密切相关，对铁电器件的失效有重要影响。该项目将深入了解目前尚不清楚的铁电材料中复杂的断裂过程，并将有助于提高铁电器件和系统的性能和可靠性。 该项目还将培训研究生和本科生，改善研究生和本科生课程，并为K-12学校的教师和学生提供外展活动。

The research objective of this grant is to elucidate the fracture of ferroelectrics, a complicated process that involves interplay between crack propagation and ferroelectric domain switching at nanometer scale. A computational phase-field method will be developed to simulate crack propagation and domain switching in ferroelectrics, and piezoresponse force microscopy will be applied for in-situ observation of such microstructure evolution in ferroelectrics under electrical, mechanical, and thermal loadings. These two techniques will be combined to investigate the fracture behavior of various ferroelectric crystals and ceramics, enabling direct comparison between computational simulations and microscopic characterization at a length scale that is most relevant to the underlying physical processes.Ferroelectrics is an important class of technological materials that are widely used as sensors, actuators, capacitors, and nonvolatile memories, and many of their applications depend on ferroelectric domain switching triggered by external fields. Ferroelectric fracture process is closely coupled with domain switching, and has important influences on the failure of ferroelectric devices. The project will shed insight on the complicated fracture processes in ferroelectric materials that is not well understood, and will help improve the performance and reliability of ferroelectric devices and systems. The project will also train graduate and undergraduate students, improve graduate and undergraduate curriculums, and offer outreach activities for K-12 school teachers and students.