CAREER: Understanding Strain and Strain Relaxation Mechanisms in Complex Two-Dimensional Materials

该学院早期职业发展(Career)奖支持研究二维(2D)薄膜如何变形以释放应变，以及如何利用这一知识来设计2D材料的新应用。由于2D材料的原子很薄，变形机制和缺陷对其力学、电学和化学性质起着至关重要的作用。然而，由于在多个长度尺度上表征的挑战，对于这些材料中的应变松弛如何不同于它们的块体对应物的基本理解仍然是难以捉摸的。该项目旨在开发新的电子显微镜方法来观察和理解新的应变松弛机制。从这项研究中获得的见解将推动复杂2D材料在柔性电子、量子计算、催化和保护涂层中的使用。此外，该项目将支持几项活动，以支持更广泛地参与STEM，重点放在代表性不足的少数群体和妇女身上，包括为当地高中教师制定的教师研究经验方案，与当地博物馆合作为年轻学习者进行的互动科学演示，以及通过课程开发将研究和教育结合起来。这个项目的中心假设是，除了传统上观察到的基于位错的机制外，还有其他新的变形机制有助于2D材料的应力松弛。为了研究这种可能性，本项目将使用最先进的四维扫描电子显微镜(4D-STEM)和相关技术来绘制2D异质结构中的晶格应变和变形。通过研究不同尺寸和形状的2D外延异质结构，有望全面了解复杂2D材料中的新的变形机制。这一知识将使对这些材料及其异质结构中的应变和缺陷进行精确和可预测的工程设计成为可能，对先进器件的开发具有重要意义。该项目由土木、机械和制造创新部门(CMMI)的材料和结构力学(MOMS)计划和材料研究部门(DMR)的固体状态和材料化学(SSMC)计划共同资助。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。

This Faculty Early Career Development (CAREER) award supports research to investigate how two-dimensional (2D) films deform to release strain, and how to leverage this knowledge to engineer new applications of 2D materials. Deformation mechanisms and defects play a critical role in the mechanical, electrical, and chemical properties of 2D materials due to their atomic thinness. However, a fundamental understanding of how strain relaxation in these materials differ from their bulk counterparts remains elusive due to challenges in characterization at multiple length scales. This project aims to develop new electron microscopy approaches to observe and understand novel strain relaxation mechanisms. The insights gained from this study will advance the use of complex 2D materials in flexible electronics, quantum computing, catalysis, and protective coatings. Additionally, the project will support several activities to support broader participation in STEM, with a focus on underrepresented minorities and women, including a Research Experience for Teachers program for local high school teachers, interactive science demonstrations for young learners in collaboration with a local museum, and integration of research and education through curriculum development.Conventional understanding of strain relaxation in bulk materials have not been successful in describing the deformation behavior of 2D materials and heterostructures. The central hypothesis of this project is that additional novel deformation mechanisms besides the traditionally observed dislocation-based mechanisms contribute towards stress relaxation in 2D materials. To investigate this possibility, this project will use state-of-the-art four-dimensional scanning transmission electron microscopy (4D-STEM) and related techniques to map the lattice strain and deformations in 2D heterostructures. By investigating various sizes and shapes of 2D epitaxial heterostructures, a comprehensive understanding of novel deformations mechanisms in complex 2D materials is expected. This knowledge will enable precise and predictable engineering of strain and defects in these materials and their heterostructures, with significant implications for the development of advanced devices. This project is jointly funded by the Mechanics of Materials and Structures (MoMS) program in the Division of Civil, Mechanical and Manufacturing Innovation (CMMI) and the Solid State and Materials Chemistry (SSMC) program in the Division of Materials Research (DMR).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.