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验证这样一个假设，即通过控制包括二维(2D)原子层在内的无机纳米材料的形貌、尺寸和衬底诱导的屈曲，可以增强弯曲电响应。与描述均匀机械变形引起的电极化的压电性不同，由应变梯度引起的电极化，即挠性电，长期以来一直被忽视，因为它在大块陶瓷中相对较弱，在达到大应变梯度之前就会破裂。另一方面，纳米材料可以经受住由微尺度屈曲和褶皱产生的较高数量级的应变梯度。最近，在没有直接实验证据的情况下，在纳米尺度上发现了增强的机电耦合，并被假想地归因于挠曲电性。该项目将通过实验与建模和模拟相结合的方式在四个研究方向进行：i)钛酸钡纳米线、纳米带和纳米薄膜在可变形衬底上的弯曲电响应；ii)由可变形衬底支撑的原子薄的六方氮化硼(h-BN)和二硫化钼(MoS2)中的机电耦合；iii)在可变形衬底上的弯曲电纳米材料的失效机制和断裂力学；以及iv)珍珠层激发的多层堆积的尺度弯曲电响应。这项研究将使基于柔性电原理的传感器、执行器和能量收集器的合理设计、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，并使未被充分代表的群体接触到前沿的跨学科研究。该协会将在全校范围内开设一门跨学科的课程，主题是“柔性和可伸缩电子设备的力学和材料”。PI将通过工程研究中心(ERC)-移动计算和移动能源技术纳米制造系统(NASCENT)和德克萨斯大学奥斯汀分校女性工程项目(WEP)建立的联系，为来自少数族裔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参观和大学范围内的推广活动准备可穿戴可伸缩电子设备和发电机的演示。PI计划通过出版物、会议、在线期刊俱乐部和视频在全球范围内传播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.