CAREER: Fundamentals and synthesis of new compositions and shapes/microstructures of 3D and 2D carbides, nitrides and carbonitrides (MAX phases and MXenes)

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。新的、更好的材料的发现可以导致新的和创新的技术的进步，例如以电池、传感器和磁铁为中心。因此，这一材料的发现以及了解它们的特征，如它们的结构和性质，以及这些因素在制备过程中可能受到的影响，对于我们的经济和社会确保国家的繁荣至关重要。凭借这一职业奖，亚利桑那州立大学的克里斯蒂娜·伯克尔教授将研究含有不同金属和碳或氮(或两者兼有)的材料，分别称为碳化物或氮化物(碳氮化物)。这些材料为发现具有有用性能的新型材料提供了一个巨大的游乐场，因为研究人员(I)混合和匹配不同的元素，(Ii)以不同的形状生产它们。(中空)球体、薄膜或金属丝的制造为这些材料在更多领域的应用铺平了道路。例如，人们可以设想将电线集成到面料中，并生产出可穿戴的电子产品，以监测汗液水平或在旅途中产生能量。此外，该团队可以将这些层状固体分解成原子薄片，厚度不到十亿分之一米(不到一纳米)。达到这种大小范围时，就会出现在较大结构中无法达到的特殊物理现象。所有这些新型材料都是一个理想的平台，可以(通过研讨会和学生参与)连接和教育公众、当地高中和校园社区，并(通过冬季学校和社交媒体)提高材料科学和化学在亚利桑那州、美国和世界各地的影响力和知名度。伯克尔教授将制定一项包容性计划，通过在STEM(科学、技术、工程和数学)中树立榜样和创造未来的榜样来加强教育、指导和招聘工作。技术摘要亚利桑那州立大学的克里斯蒂娜·伯克尔教授将利用这一职业奖项，合成属于Max阶段和MXenes家族的三维和二维层状化合物的新成员以及新的形状和微观结构。主要的目标材料是：(I)(Carbo)氮化物，因为它们很稀少，因此比各自的碳化物被探索得少得多，但有望改善机械稳定性(固溶强化)和更高的导电性(氮的额外电子)和(Ii)含铬、锰和钼的相，因为其有趣的磁性(铬、锰)和催化行为(钼)，其研究仍处于起步阶段。这项建议侧重于湿化学辅助技术，这些技术(I)受益于前体在原子/分子尺度上的亲密混合，反应时间和温度通常较低(这导致最大相颗粒而不是典型的笨重结构，还可以稳定亚稳定相)，以及(Ii)允许将液体/凝胶前体混合物高级加工成其他形状，如线状和中空微球，这是固相反应中使用的粉末所不可能做到的。为了评估它们的稳定性/降解性和功能特性，这些材料将接受机械测试(纳米压痕)和量热，以及电子/磁性传输和催化测量。这一提议的结果将是合成全新类型的结构和功能材料，并将为各种基于应用的领域奠定基础，如建筑(自我修复材料、耐火材料)、能源技术(磁热、催化剂、传感器)、消费电子产品(涂层)和电子纺织品(“智能”/功能织物)。这些材料是联系和教育公众、当地高中和校园社区的理想平台(通过研讨会和学生参与)，并通过冬季学校和社交媒体提高材料科学和化学在亚利桑那州、美国和世界各地的影响力和知名度。该团队制定了一项包容性计划，通过在STEM中树立榜样和创建未来的榜样来加强教育、指导和招聘工作，目标是打破障碍，证明科学中有为每个人服务的空间。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).The discovery of new, and better, materials can lead to advances in new and innovative technologies, for example centered around batteries, sensors, and magnets. This materials discovery together with understanding their characteristics, such as their structure and properties, and how these factors can be influenced during their preparation are therefore of utmost importance for our economy and society securing the country’s prosperity. With this CAREER award, Professor Christina Birkel at Arizona State University will investigate materials that contain different metals and either carbon or nitrogen (or both), called carbides or nitrides (carbonitrides), respectively. These materials offer a huge playground for the discovery of new types of materials with useful properties since the researchers (i) mix and match different elements, and (ii) produce them in different shapes. The creation of (hollow) spheres, films, or wires paves the way to even more areas where these materials can be utilized. One can, for example, envision to integrate the wires into fabrics and produce wearable electronics that monitor sweat levels or produce energy on-the-go. Furthermore, the team can break these layered solids down into atomically thin sheets, which is less than one-billionth of a meter (less than a nanometer). Reaching this type of size regime, special physical phenomena occur that are not accessible in the larger structures. All of these new types of materials are an ideal platform to connect to and educate the public, local high-school and campus communities (through seminars and student involvements), and to increase the impact and visibility of Materials Science and Chemistry within Arizona, the US and worldwide (through winter schools and social media). Prof. Birkel will develop an inclusive program to strengthen education, mentoring and recruitment efforts through being role models and creating future role models in STEM (science, technology, engineering, and math).TECHNICAL SUMMARY With this CAREER award, Professor Christina Birkel at Arizona State University will synthesize new members as well as new shapes and microstructures of the three- and two-dimensional layered compounds that belong to the families of MAX phases and MXenes. The main target materials are: (i) (Carbo)nitrides, because they are scarce and therefore much less explored than the respective carbides yet hold promise for improved mechanical stability (solid solution strengthening) and higher conductivities (additional electron of the nitrogen) and (ii) Cr-, Mn- and Mo-containing phases, because of intriguing magnetic (Cr, Mn) and catalytic behavior (Mo) whose investigations are still in their infancy. This proposal has a strong and distinguishing focus on wet chemical-assisted techniques which (i) benefit from intimate mixing of the precursors on the atomic/molecular scale and with that typically reduced reaction times and temperatures (this leads to MAX phase particles instead of the typical bulky structures and can also stabilize metastable phases), and (ii) allow for advanced processing of the liquid/gel precursor mixture into additional shapes, e.g. wires and hollow microspheres, that would not be possible with powders used in solid-state reactions. To evaluate their stability/degradation and functional properties, the materials will be subject to mechanical testing (nanoindentation) and calorimetry as well as electronic/magnetic transport and catalytic measurements. The outcome of this proposal will be the synthesis of entirely new types of structural and functional materials and will lay the groundwork for various application-based areas, such as construction (self-healing materials, refractory materials), energy technologies (magnetocalorics, catalysts, sensors), consumer electronics (coatings) and electronic textiles (“smart”/functional fabrics). These materials are an ideal platform to connect to and educate the public, local high-school and campus communities (through seminars and student involvements), and to increase the impact and visibility of Materials Science and Chemistry within Arizona, the US and worldwide (through winter schools and social media). The team develops an inclusive program to strengthen education, mentoring and recruitment efforts through being role models and creating future role models in STEM with the goal to break down barriers and demonstrate that there is space in science for everyone.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.