Metal Diborides: Investigating the Structure, Processing, and Properties of a New Class of Two-Dimensional Materials

非技术描述：金属二硼化物是一类化学成分为MB2的陶瓷材料，其中M可以是许多不同的金属。它们有一个共同的结构，由金属原子层隔开的硼层堆叠而成。这些材料的各种出色特性的例子包括二硼化镁的超导性和二硼化钛和二硼化锆对极高温度的耐受性。金属二硼化物还可用于航天器的弹道装甲和隔热罩。然而，制备金属二硼化物的常规方法导致厚的脆性材料，其没有利用其组成硼片的柔性二维（2D）性质。PI最近开发了一种方法来直接产生大量的2D金属二硼化物，其由单层到几层原子级薄片组成。该项目的重点是详细研究这种新型2D陶瓷的结构、性能、加工和性能。测试了悬浮在多孔表面上或掺入聚合物中的少层金属二硼化物的机械性能。薄膜的二维金属二硼化物的研究，其潜在的重量轻，灵活的超导体。总的来说，这些研究旨在利用金属二硼化物在使用常规材料加工技术不可能的应用中的特殊性能，并改善其在常规使用领域中的性能。该项目的教育目标是对研究生和本科生进行先进材料研究方面的培训，将研究成果纳入PI为研究生和本科生开设的跨学科课程，并通过开放式科学活动和家庭虚拟科学工具包向普通公众的学生和家庭进行宣传。该项目的重点是详细了解使用溶液相处理和微机械解理技术制备的金属二硼化物的2D片材的结构和性能。这些2D材料的结构和组成进行了研究，以原子尺度的像差校正透射电子显微镜，扫描隧道显微镜，电子能量损失谱，和能量色散X射线光谱。使用原子力显微镜和拉伸测试设备，正在研究从2D金属二硼化物的单个微观片材到由2D金属二硼化物增强的宏观聚合物复合材料的不同长度尺度的机械测量。溶液处理，柔性薄膜的二维金属二硼化物MgB 2正在研究其潜在的超导行为。因此，该研究项目提供了金属二硼化物的电子和机械特性的新基础知识，一旦它们只有几个原子层厚。对2D金属二硼化物陶瓷的性能和加工的更好理解有助于将其整合到传统大块陶瓷无法实现的可拉伸和柔性形式中，并为这些化合物在结构增强聚合物复合材料和可弯曲超导体中产生新的应用领域。

NON-TECHNICAL DESCRIPTION: Metal diborides are a class of ceramic materials with the chemical composition MB2, where M can be many different metals. They have a common structure of stacked sheets of boron separated by layers of metal atoms. Examples of the diverse, outstanding properties of these materials include superconductivity in magnesium diboride and resistance to extremely high temperatures in titanium diboride and zirconium diboride. Metal diborides also find application in ballistic armor and heat shields for spacecraft. However, conventional methods of preparing metal diborides result in thick, brittle materials that do not take advantage of the flexible, two-dimensional (2D) nature of their constituent boron sheets. The PIs recently developed a method to directly generate substantial amounts of 2D metal diborides composed of single- to few-layer atomically thin sheets. This project is focused on studying in detail the structure, properties, processing, and performance of this new class of 2D ceramics. Few-layer metal diborides suspended across porous surfaces or incorporated into polymers are tested for their improved mechanical properties. Thin films of the 2D metal diborides are investigated for their potential as lightweight and flexible superconductors. Overall, these studies aim to exploit the exceptional properties of the metal diborides in applications not possible using conventional materials processing techniques and to improve their performance in their conventional areas of use. The educational goals of this project are the training of graduate and undergraduate students in advanced materials research, incorporation of research results into the PIs' interdisciplinary courses for graduate and undergraduate students, and outreach to students and families in the general public through open house science events and at-home virtual science kits.TECHNICAL DETAILS: This project is focused on understanding in detail the structure and properties of 2D sheets of metal diborides prepared using solution-phase processing and micromechanical cleavage techniques. The structure and composition of these 2D materials are studied down to the atomic scale by aberration corrected transmission electron microscopy, scanning tunneling microscopy, electron energy loss spectroscopy, and energy dispersive X-ray spectroscopy. Mechanical measurements across different length scales, starting from individual microscopic sheets of 2D metal diborides to macroscopic polymer composites reinforced by 2D metal diborides, are being studied using atomic force microscopy and tensile testing equipment. Solution-processed, flexible thin films of the 2D metal diboride MgB2 are being investigated for their potential superconducting behavior. This research project is thus providing new fundamental knowledge of the electronic and mechanical properties of the metal diborides once they are only a few atomic layers thick. The improved understanding of the properties and processing of 2D metal diboride ceramics is facilitating their integration into stretchable and flexible forms unavailable to their conventional bulk counterparts, and yielding new application areas for these compounds in structurally reinforced polymer composites and bendable superconductors.