Nanoscale Modulated Checkerboard Structures in Li-based A-site Perovskites

非技术描述：纳米级化学、结构和功能控制方面的进展对于纳米技术应用的新材料工程至关重要。这个研究项目的重点是一种新的无机材料家族，它可以自发地组装成有序的“棋盘”纳米结构，具有前所未有的完美水平。这项工作将研究这些新材料的形成和原子结构，以了解导致其稳定的力，并研究裁剪其组装长度尺度的方法。对这些系统中构建块排列的显著控制水平提供了一个机会，可以使用它们的表面结构作为模板来组织放置在其表面上的纳米级对象。这一目标的实现可能代表了纳米科学和纳米技术领域自组装的新范式，这些领域对美国技术至关重要。这项研究将在纳米材料的合成和结构表征方面培养本科生和研究生，并使他们接触到纳米技术的许多进展。项目负责人和学生将参与为高中学生和教师开发新的实验室模块，以说明电子显微镜在揭示和理解纳米级结构和化学中的使用。技术细节：该项目专注于锂基a位钙钛矿家族，其中自发的纳米级相分离成有序的富锂域和缺锂基质，产生具有非凡完美水平的介观有序棋盘结构。棋盘结构的形成似乎是通过独立分解进行的；机制研究将关注为什么这些锂系统的体化学和键合促进了对纳米尺度周期性的如此显著的控制。这种理解将用于设计新的大块棋盘化学，其中磁性和电子功能将被纳入构建块。棋盘格系统的表面呈现出独特的调制纳米结构；这些将使用自组装的单层来制作图案，随后将用于自发地组装放置在表面上的纳米大小的物体。该项目的实验部分将使参与的学生能够发展最先进的电子显微镜技术的专业知识，并使用国家设施通过中子散射研究他们的样品。

NON-TECHNICAL DESCRIPTION: Advances in the control of chemistry, structure and functionality at the nanoscale are critical in enabling the engineering of new materials for application in nanotechnology. This research project focuses on a novel family of inorganic materials that spontaneously assemble into ordered "checkerboard" nanostructures with unprecedented levels of perfection. The proposed work will study the formation and atomic structure of these new materials to understand the forces responsible for their stabilization and investigate methods for tailoring the length scale of their assembly. The remarkable level of control over the arrangement of the building blocks within these systems provides an opportunity to use their surface structure as a template to organize nano-sized objects placed on their surface. The achievement of this aim could represent a new paradigm for self-assembly in nanoscience and nanotechnology, areas that are vital to US technology. The research will train undergraduate and graduate students in the synthesis and structure characterization of nanomaterials and expose them to the many advances being made in nanotechnology. The PI and students will be involved in the development of new laboratory modules for high school students and teachers to illustrate the use of electron microscopy in revealing and understanding structure and chemistry at the nano-level.TECHNICAL DETAILS: The project focuses on a family of Li-based A-site perovskites where spontaneous nanoscale phase separation into ordered Li-rich domains and a Li-deficient matrix produces mesoscopic ordered checkerboard structures with extraordinary levels of perfection. The formation of the checkerboard structure appears to proceed via spinodal decomposition; the mechanistic studies will focus why the bulk chemistry and bonding of these Li systems promote such a remarkable level of control over the nanoscale periodicity. This understanding will be used to design new bulk checkerboard chemistries where magnetic and electronic functionality will be incorporated into the building blocks. The surfaces of the checkerboard systems present a unique modulated nanostructure; these will be patterned using self-assembled monolayers, which subsequently will be utilized to spontaneously assemble nanometer-sized objects placed on the surface. The experimental parts of the project will enable the students involved to develop expertise in state-of-the-art techniques in electron microscopy and use national facilities to study their samples by neutron scattering.