CAREER: Understanding Quasicrystalline Superstructures Formed from Pyramidal Nanocrystals

非技术概述：结晶材料的特征在于具有规则的重复原子图案的结构，而玻璃等非晶材料则是无序的。 准晶（QC）材料是不寻常的，因为它们是有序的，但不是周期性的，使它们成为一种根本不同的材料类别，既不是晶体也不是玻璃。独特的结构赋予QC材料有趣的热、电、磁、光学和机械性能，使其可用于不粘和隔热涂层或耐腐蚀和极强的医疗器械和手术器械材料等应用。 这个职业奖，由材料研究部内的固态和材料化学计划支持，使研究QC材料自组装从纳米形状的纳米颗粒（纳米晶体）。该项目包括新QC材料结构和形成过程的详细表征，并开发新的表征和生长方法，可适用于研究其他软物质组装系统。该研究提供了丰富的基本和视觉兴趣，以及技术相关性，所有这些都被纳入PI的教育和推广活动。YouTube电影通过各种社交媒体平台创作和推广，没有行话，讲故事的风格。 这些视频独特地利用了这一基础研究所创造的美丽而引人注目的QC图案与现实世界的艺术，装饰和建筑设计之间的联系。此外，该项目还通过每年的STEM日支持对当地高中生的宣传。技术摘要：这个职业项目，由材料研究部内的固态和材料化学计划支持，整合了从纳米晶体（NC）组装的准晶（QC）超结构的教育和研究。将纳米碳自组装成新型超结构是一种很有前途的方法，可以将纳米级的性质转移到宏观材料中，最终实现高效的太阳能电池、低能耗的照明和显示器以及更灵敏的生物传感器。为了实现这些机会，需要对NC上层结构的形成进行合理的控制。准晶是有序的，但不是周期性的，因此无法分类为晶体或玻璃。与传统的NC晶体超结构相比，NC QC超晶格（QC-SL）的研究处于起步阶段。它仍然是一个悬而未决的问题，如何组织成这些长程有序但非周期性的晶格，方法来生产和表征这些独特的材料是有限的。为了解决这些问题，PI的团队首先合成各向异性金字塔NC并将其组装成QC超结构。然后，这些材料的特点是使用原位和非原位真实的空间方法（电子显微镜和断层扫描）的组合，辅以倒易空间测量（电子衍射和X射线散射）。除了2D超晶格，通过微流体生长的3D QC超晶体将使用新的超晶体学技术进行结构表征。总之，这些工具提供了关于这些结构的包装的精致细节，并指定了各个NC的相对取向。这些信息阐明了NC合成、超结构形成和转换如何协同工作以创建QC超结构。 该研究的成果被整合到一系列面向年轻学生和成年人的外展活动中，这些活动旨在激发人们对科学和技术的兴趣。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Summary:Crystalline materials are characterized by a structure with a regular, repeating pattern of atoms, while amorphous materials such as glass are disordered. Quasicrystalline (QC) materials are unusual in that they are ordered but not periodic, making them a fundamentally different category of materials which is neither a crystal nor a glass. The unique structure gives QC materials intriguing thermal, electrical, magnetic, optical and mechanical properties, making them useful for applications such as non-stick and thermally insulating coatings or corrosive-resistant and extremely strong materials for medical devices and surgical instruments. This CAREER award, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, enables study of QC materials self-assembled from pyramid-shaped nano-sized particles (nanocrystals). The project includes detailed characterization of new QC materials’ structures and formation processes and also develops new characterization and growth methods that may be applicable to studying other soft matter assembly systems. The research offers ample fundamental and visual interest, as well as technological relevance, all of which are integrated into the PI’s education and outreach activities. YouTube movies with a jargon-free, storytelling style are created and promoted through various social media platforms. These videos take unique advantage of the connection between the beautiful and eye-catching QC patterns created by this fundamental study and real-world art, decoration and architectural design. Additionally, the project supports outreach to local high school students through an annual STEM Day. Technical Summary:This CAREER project, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, integrates education and research on quasicrystalline (QC) superstructures assembled from pyramid-shaped nanocrystals (NCs). Self-assembly of NCs into novel superstructures is a promising approach for transporting nanoscopic properties into macroscopic materials to eventually enable highly efficient solar cells, low-energy-consumption lighting and displays, and more sensitive biological sensors. To realize these opportunities requires rational control over the formation of NC superstructures. Quasicrystals are ordered but not periodic and as such defy classification as either a crystal or a glass. The study of NC QC superlattices (QC-SLs) is in its infancy compared to efforts on conventional NC crystalline superstructures. It remains an outstanding question how NCs organize into these long-range ordered yet aperiodic lattices; methods to produce and characterize these unique materials are limited. To address these issues, the PI's group first synthesizes anisotropic pyramidal NCs and assembles them into QC superstructures. These materials are then characterized using combinations of in situ and ex situ real space methods (electron microscopies and tomography) complemented by reciprocal space measurements (electron diffraction and X-ray scattering). In addition to 2D superlattices, 3D QC supercrystals grown via microfluidics will be structurally characterized using a new super-crystallography technique. Together, these tools provide exquisite detail concerning the packing of these structures and specify the relative orientation of individual NCs. Such information clarifies how NC synthesis, superstructure formation and transformation work together to create QC superstructures. Results generated in this research are integrated into a series of outreach activities that target younger students and adults alike with compelling, visual stories designed to provoke interest in science and technology.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.