CAREER: Property Tailoring and Reliability in Ferroic Film Actuators

9502431 Trolier-McKinstry这项研究解决了铁性薄膜行为中尚未解决的基本问题，包括畴壁对薄膜特性的贡献方式，微观结构和机电各向异性之间的相关性，薄膜应力状态的作用以及致动器器件的可靠性。 将利用激光烧蚀来制备0.1 - 10微米厚度范围内的改性锆酸铅和锆酸钛铅膜。 最初的重点将放在开发平面和非平面基板上的厚膜沉积条件。特别感兴趣的研究是了解薄膜的微结构和应力分布如何调制铁电薄膜的机电各向异性的发展。 温度，偏置电场，薄膜应力和应力在下面的电极材料的材料特性的影响将被评估和利用开发一个模型的方式，其中铁弹域与二维应力相互作用。 这些研究将与薄膜和厚膜致动器中的主要退化和失效机制的确定相结合。 将特别强调确定应力集中和裂纹产生的器件几何形状的作用。 有限元建模将用于计算几种不同致动器结构中存在的应力。 将制定薄膜致动器中可接受的应力集中准则。 作为本研究的一个辅助部分，功能梯度薄膜将被研究。 %了解薄膜铁电材料的基本特征将具有科学技术意义。 此外，这个项目还有一个很强的教育部分，强调新课程的开发，重点是指导研究生、本科生和大学预科生。 主要研究者将开发两个新的课程“材料的光学性质和光学表征”和“电子和光子材料的性质”。“为本科生和大学预科生提出的辅导计划的基石是将参与者融入正在进行的研究项目。 计划中的教育活动还包括为目前没有材料科学课程的四年制学院的教师开发课程材料。***

9502431 Trolier-McKinstry This research addresses unresolved fundamental issues in the behavior of ferroic films, including the manner in which domain walls contribute to film properties, correlation between microstructure and electromechanical anisotropy, the role of thin film stress states, and the reliability of actuator devices. Laser ablation will be utilized to prepare modified lead zirconate and lead titanium zirconate films in the range of 0.1 - 10 micrometer thickness. Initial emphasis will be placed on developing deposition conditions for thick films on planar and non-planar substrates. Of especial interest in the research is the development of understanding how film microstructure and stress distribution modulate the electromechanical anisotropy of ferroelectric films. The influence on the material properties of temperature, bias electric field, film stress, and stress in the underlying electrode material will be evaluated and utilized to develop a model for the way in which ferroelastic domains interact with two-dimensional stresses. These studies will be coupled with a determination of the principal degradation and failure mechanisms in thin and thick film actuators. Special emphasis will be placed on determining the role of device geometry in stress concentration and crack generation. Finite element modeling will be used to calculate the stresses present in several different actuator structures. Guidelines for acceptable stress concentrations in film-based actuators will be developed. As a subsidiary component of this research, functionally graded films will be investigated. %%% The understanding of fundamental features of thin film ferroelectric materials will be of scientific and technological significance. Additionally, there is a strong educational segment to this project which stresses development of new courses and a focus on mentoring graduate, undergraduate, and pre-college students. The principal investigator will develop two new courses in ''Optical Propert ies and Optical Characterization of Materials" and ''Properties of Electronic and Photonic Materials." The cornerstone of the proposed mentoring program for undergraduate and pre-college students is integration of participants into ongoing research projects. The educational activities planned also include course materials development for faculty at four year colleges currently without materials science courses. ***