Novel Mechanical Functionality in Nano-Architectured Ferroelectrics via Rational Design of Free Energy Landscapes

铁电材料是用于传感和通信的重要材料。通过施加电场，可以在铁电材料中诱导机械运动，电场可以控制纳米尺度的电偶极子簇的方向，也就是众所周知的磁区。薄膜生长的进步现在允许通过将化学成分或磁区不同的层组合到单个结构中来制造人造铁电材料，一次一个原子层。与传统的铁电材料相比，人工系统提供了新的方法来操纵磁畴，从而实现机械行为。该奖项旨在了解如何在人造铁电材料中设计“智能”机械行为，如用光诱导机械运动的能力，或用光或应力调整机械共振的能力。这项研究将把先进的计算技术与基于人工铁电体的微尺度机械设备的制造和表征结合起来。该项目还将提供在材料科学、物理、设备工程和数据科学等跨学科领域教育和培训研究生和本科生的机会。外展和传播工作将包括为当地初中生和高中生提供教育模块，以及为达拉斯和沃斯堡地区的科学博物馆进行展示。铁电材料是微电子机械系统(MEMS)的关键材料。薄膜外延的最新进展使人工铁电系统能够通过将组成不同的层组合成单片异质结构来创建。与均匀组成的系统相比，人工系统提供了前所未有的途径来调整自由能格局，从而实现机械响应。这项提议旨在阐明如何在人工铁电异质结构中合理地设计自由能景观，从而实现机械功能。特别令人感兴趣的是在自由能环境中处于接近不稳定状态的材料，这些材料可能会导致对微扰的戏剧性机械反应。这种材料还可以显示出智能功能特性，包括光致机械驱动和可以按需调谐的机械共振。该方法包括铁电异质结构的相场模拟，这些铁电异质结构由不同成分的钙钛矿ABO_3(A=Sr，Ba；B=Ti，Zr)组成。通过高通量相场模拟生成的数据库上的机器学习将识别异质结构的关键材料特征(或“指纹”)并将其与机械响应相关联。异质结将通过氧化物分子束外延技术在硅上外延实现。微梁谐振器和悬臂梁将从这些异质结构中制造出来，并将在机械应力和光激励的扰动下探索机电行为，以形成闭环研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Ferroelectrics are important materials used for sensing and telecommunication. Mechanical motion can be induced in ferroelectrics by applying electric fields, which manipulate the orientation of nanoscale clusters of electric dipoles, known as domains. Advances in the growth of thin films now allow artificial ferroelectric materials to be created by combining layers that differ in chemical composition or domains into a single structure, one atomic layer at a time. In comparison to traditional ferroelectric materials, artificial systems offer new ways to manipulate domains and thereby mechanical behavior. This award aims to understand how “smart” mechanical behaviors, such as the ability to induce mechanical motion with light or the ability to tune mechanical resonance with light or stress, can be engineered in artificial ferroelectrics. This research will integrate advanced computational techniques with the fabrication and characterization of microscale mechanical devices based on artificial ferroelectrics. The project will also provide opportunities to educate and train graduate and undergraduate students in the cross-disciplinary areas of materials science, physics, device engineering, and data science. Outreach and dissemination efforts will include educational modules for local middle and high school students, as well as displays for Dallas and Fort Worth area science museums. Ferroelectrics are key materials in microelectromechanical systems (MEMS). Recent advances in thin-film epitaxy have enabled artificial ferroelectric systems to be created by combining compositionally diverse layers into monolithic heterostructures. In contrast to systems of homogeneous composition, artificial systems offer unprecedented pathways to tune the free energy landscape, and thereby mechanical response. This proposal aims to elucidate how free energy landscapes, and thereby mechanical functionality, can be rationally engineered in artificial ferroelectric heterostructures. Of particular interest are materials poised near instabilities in the free energy landscape that may lead to dramatic mechanical response to perturbations. Such materials could also exhibit smart functional characteristics, including light-induced mechanical actuation and mechanical resonance that can be tuned on-demand. The approach involves phase-field modelling of ferroelectric heterostructures comprised of perovskite ABO3 (A = Sr, Ba; B = Ti, Zr) layers of varying composition. Machine learning on a database generated by high-throughput phase-field simulations will identify and correlate key material characteristics (or “fingerprints”) of heterostructures to mechanical response. Heterostructures will be experimentally realized through epitaxial growth on silicon using oxide molecular beam epitaxy. Microbeam resonators and cantilevers will be created from these heterostructures, and electromechanical behavior will be probed under perturbation of mechanical stress and optical excitation to form a close-loop study.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.