CAREER: Harnessing Microfabrication for Chemical Control During High Pressure Synthesis of Non-Equilibrium Carbides

职业：在非平衡碳化物高压合成过程中利用微加工进行化学控制

• 批准号: 2237478
• 负责人: James Walsh
• 金额: $ 69.7万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2028-02-29
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237478&HistoricalAwards=false
• 关键词: CAREER; Harnessing; Microfabrication; Chemical; Control

PART 1: NON-TECHNICAL SUMMARYTechnology often relies on the use of materials with specific properties. Since these properties arise from microscopic interactions between atoms, we depend on chemists to discover and optimize the recipes for making them. For example, the stainless steels used in surgical tools and medical implants rely on the presence of very specific amounts of chromium, which prevents oxygen from converting the iron and nickel into rust. Although many materials can be created using high temperatures, some of them—such as diamond—also require very high pressures to form. High pressure chemistry is much less explored than traditional chemistry, but it has already led to the discovery of many exciting new materials with properties such as lossless electrical conductivity, exceptional hardness, and exotic forms of magnetism. One major obstacle in the field is that the exceedingly small scales required to perform high-pressure reactions make it difficult for chemists to fine tune their recipes for preparing materials as easily as they can for reactions under normal pressure. This in turn makes it much more difficult to investigate and tune the new high-pressure materials being discovered. Through this award, funded by the Solid State and Materials Chemistry program and the Ceramics program in the Division of Materials Research at NSF, Prof. Walsh's research team develops a completely new approach to high-pressure synthesis that uses cutting-edge microfabrication methods to precisely tune elemental ratios to a much higher precision than is possible with current methods. This project supports the expert training of graduate students as they develop these next-generation methods, greatly strengthening our nation’s future scientific workforce. The award also enables the development of new educational kits that provide high school and undergraduate students with hands-on access to high-pressure science, promoting their exposure to forefront scientific disciplines.PART 2: TECHNICAL SUMMARYHigh-pressure synthesis is a rapidly growing field that is enabling the experimental exploration of uncharted phase space in search of novel materials. However, a longstanding issue in the field has been a poor control over elemental composition under the strict constraints required to access extreme pressures. This has precluded experiments that rely on an exact control of stoichiometry, such as site doping studies or high-yield syntheses, which in turn has limited the degree to which the bulk properties and stabilities of unrecoverable phases can be studied. With this CAREER project, Prof. Walsh implements and expands novel methods developed in his laboratory to experimentally examine longstanding predictions surrounding the superconducting properties of high valence electron count mid-row carbides that until now have remained untestable. Alongside these studies, his team also examines the effect that chemical site doping has on the stability fields of unquenchable high-pressure phases. The exquisite control of chemical composition required for these studies is enabled by a completely new approach to sample preparation that uses sputtering and microlithography to prepare micropellet precursors with precise chemical composition and spatial homogeneity. These precursors are readily integrated with the diamond anvil cell method, allowing for the collection of X-ray diffraction and spectroscopic data under extreme pressures. The discovery of new methods for optimizing the properties and recoverability of high-pressure phases would break new ground toward their integration with existing technology infrastructure, greatly enhancing their potential for societal impact.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.

第1部分：非技术摘要技术通常依赖于具有特定特性的材料的使用。由于这些特性来自原子之间的微观相互作用，因此我们依靠化学家发现和优化制造它们的食谱。例如，用于手术工具和医疗叉的不锈钢依赖于非常具体的铬的存在，从而防止氧气将铁和镍转化为生锈。尽管可以使用高温创建许多材料，但其中一些材料（例如钻石）也需要很高的压力才能形成。高压化学的探索要比传统化学少得多，但是它已经导致发现了许多令人兴奋的新材料，这些新材料具有无损的电导率，出色的硬度和异国情调的磁性形式。该领域的一个主要障碍是，进行高压反应所需的较小规模使化学家难以微调其食谱以尽可能轻松地准备材料，以在正常压力下进行反应。反过来，这使得调查和调整发现的新高压材料变得更加困难。通过该奖项，由NSF材料研究部的固态和材料化学计划和陶瓷计划资助，沃尔什教授的研究团队开发了一种全新的高压合成方法，该方法将最先进的微型生物生物元素元素比率确切地调整为比当前方法更高的精确性。该项目支持研究生的专家培训，因为他们开发了这些下一代方法，从而大大加强了我们国家未来的科学劳动力。该奖项还可以开发新的教育套件，这些新教育套件为高压科学提供动手访问，促进他们接触前沿科学学科。第2部分：技术摘要高压合成是一个快速增长的领域，可在搜索新颖的新颖材料方面进行实验探索。但是，该领域的长期问题是，在访问极端压力所需的严格限制下，对元素组成的控制很差。这排除了依赖于化学计量的精确控制的实验，例如位点掺杂研究或高收益合成，这又限制了可以研究不可恢复相的批量特性和系统的程度。通过这个职业项目，沃尔什教授实施并扩展了其实验室中开发的新方法，以实验性地检查了围绕高价电子中部碳化物的超导性能的长期预测，这些预测迄今为止一直无法测试。除了这些研究外，他的团队还研究了化学位点掺杂对不可抑制高压阶段稳定场的影响。这些研究所需的化学成分的独家控制是通过一种全新的样品制备方法来实现的，该方法使用溅射和微观石印来制备具有精确化学成分和空间均匀性的微细胞前体。这些前体很容易与钻石砧细胞方法集成，从而可以在极端压力下收集X射线衍射和光谱数据。发现新方法来优化高压阶段的特性和恢复，将为与现有技术基础设施的融合融为一体，从而大大增强其对社会影响的潜力。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来通过评估来获得的支持。