CAREER: Flexoelectricity of Nanomaterials on Deformable Substrates

该学院早期职业发展（CAREER）计划奖的研究目标是测试这一假设，即可以通过控制无机纳米材料（包括二维（2D）原子层）的形态，尺寸和衬底诱导的屈曲来增强挠曲电响应。与描述由均匀机械变形引起的电极化的压电性相反，由应变梯度引起的电极化（称为挠曲电性）长期以来一直被忽视，这是由于其在大块陶瓷中的相对弱点，其将在实现大的应变梯度之前破裂。另一方面，纳米材料可以经受住由微尺度屈曲和弯曲产生的更高数量级的应变梯度。最近，增强的机电耦合在纳米尺度已被发现，并假设归因于挠曲电没有直接的实验证据。该项目将通过将实验与建模和模拟相结合，在四个研究方向进行：i）钛酸钡（BaTiO 3）纳米线、纳米带和纳米膜在可变形衬底上的挠曲电响应，ii）由可变形衬底支撑的原子级薄六方氮化硼（h-BN）和二硫化钼（MoS 2）中的机电耦合，iii）可变形衬底上的挠曲电纳米材料的失效机制和断裂力学，以及iv）通过nacre启发的多层堆叠的缩放挠曲电响应。该研究将使传感器、执行器和基于挠曲电原理的能量采集器的合理化设计、优化和放大成为可能。该计划的一个中心目标是促进跨学科研究和教学，并使代表性不足的群体接触尖端的跨学科研究。PI将在全校范围内开设一门跨学科课程“柔性和可拉伸电子器件的力学和材料”。PI将通过工程研究中心（ERC）-移动的计算和移动的能源技术纳米制造系统（NASCENT）和德克萨斯大学奥斯汀分校工程项目（WEP）中的女性建立的联系，为少数民族学院的本科生和高中生提供专门设计的跨学科研究机会。PI和学生们还将为实验室开放日和大学范围内的推广活动准备可穿戴可拉伸电子产品和发电机的演示。PI计划通过出版物，会议和在线期刊俱乐部和视频在全球范围内分发她的研究和教育成果。

The research objective of this Faculty Early Career Development (CAREER) Program award is to test the hypothesis that the flexoelectric response can be enhanced by controlling the morphology, the size, and the substrate-induced buckling of inorganic nanomaterials including two-dimensional (2D) atomic layers. In contrast to piezoelectricity, which describes electrical polarization induced by uniform mechanical deformation, electrical polarization induced by strain gradients known as flexoelectricity has long been overlooked due to its relative weakness in bulk ceramics which will rupture before large strain gradients are achieved. Nanomaterials, on the other hand, can survive orders of magnitude higher strain gradient generated by microscale buckling and wrinkling. Recently, enhanced electromechanical coupling at nanoscale has been discovered and was hypothetically attributed to flexoelectricity without direct experimental evidence. The project will be carried by combining experiments with modeling and simulations in four research thrusts: i) flexoelectric response of barium titanate (BaTiO3) nanowires, nanoribbons and nanomembranes on deformable substrates, ii) electromechanical coupling in atomically thin hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2) supported by deformable substrates, iii) failure mechanisms and fracture mechanics of flexoelectric nanomaterials on deformable substrates, and iv) scaled flexoelectric response by nacre-inspired multilayer stacking. This research will enable rationalized design, optimization and scaleup of sensors, actuators and energy harvesters based on the principle of flexoelectricity. A central goal of this program is to promote interdisciplinary research and teaching and to expose underrepresented groups to cutting edge interdisciplinary research. The PI will initiate a school-wide interdisciplinary course on "Mechanics and Materials of Flexible and Stretchable Electronics". The PI will provide interdisciplinary research opportunities specifically designed for undergraduate and high-school students from minority institutes through the connections established by the Engineering Research Center (ERC) - Nanomanufacturing Systems for Mobile Computing and Mobile Energy Technologies (NASCENT) and the Women in Engineering Program (WEP) at the University of Texas at Austin. The PI and the students will also prepare demos of wearable stretchable electronics and generators for lab open houses and for university-wide outreach activities. The PI plans to distribute both her research and education outcomes globally via publications, conferences, and online Journal Clubs and videos.