High-Pressure Synthesis of Missing Pnictide Superconductors

第1部分：非技术概述：电力的无损传输意味着进入材料的所有电力都是无损耗地传输的。如果实现，这将带来惊人的能源节约，彻底改变能源产生，并显著提高医学成像技术。所谓的超导体展示了这种无损的电力传输，这使得它们对新技术非常重要。超导体还为基础科学发现提供了潜力。超导体实现这种节能现象的机制在很大程度上还不是很清楚。了解这一机制并创造出更好的超导体对技术应用至关重要，因为目前超导在很大程度上是一种低温现象，超导体的临界温度类似于火星上的极低温度，甚至是外层空间最冷的地区。通过这一奖项，弗里德曼的研究团队致力于以理论为灵感寻找特定类型的新超导体，这可能使人们能够从根本上洞察超导的机制。该奖项由NSF材料研究部的固态和材料化学以及凝聚态物理项目资助。她的团队使用高压合成来获得化学家长期以来一直未能获得的新化合物。这项工作为研究生和博士后研究员提供跨学科培训，使他们受益于固态化学、物理和地球物理的科学交叉。培养研究生进行跨领域协作将加强我们下一代从事科学工作的劳动力。第二部分：技术总结：实现高温超导将是一项变革性的进步，其影响范围从改进的医学成像到容错电力传输。到目前为止，绝大多数新的超导体要么是偶然发现的，要么是对已知超导系统的改进，要么是通过对理论上不太可能的候选者的调查发现的。与之形成鲜明对比的是，由于预测新的超导材料存在固有的困难，新体系的定向合成还不够发达。为了实现合理的进展，需要一个明确的设计策略，这需要了解给定类别的超导体中的操作超导机制。弗里德曼提出了通过高压合成来合成明显缺失的铁铋锂盐超导体的亚类。这项工作的动机是弗里德曼最近发现的第一个固态铁-铋键，通过施加高压实现，并通过形成铋-铋相互作用来稳定。该奖项由美国国家科学基金会材料研究部的固体和材料化学以及凝聚态物理项目资助，弗里德曼的团队通过原位和块状X射线衍射和光谱方法表征了新材料。通过磁测量、电阻率和热容测量对材料进行物理探测。这些数据的汇总提供了对超导机制的洞察，以及可能的结构-功能关联。创造和理解不同的超导体为在这个复杂的领域中真正的发现提供了希望。一种新的超导体的实现将促进跨科学的合作，并使人们能够更深入地了解超导。超导体还具有巨大的社会影响潜力，从核磁共振仪器到通过电网增加电力传输。这一奖项反映了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。

Part 1: Non-Technical summary: Lossless transmission of power means that all electricity that goes into a material is transported without loss. If achieved, this would lead to astonishing energy savings, completely transform energy generation, and significantly improve medical imaging technology. So-called superconductors demonstrate this lossless transmission of electricity making them very important for novel technologies. Superconductors also offer the potential for fundamental scientific discovery. The mechanism by which superconductors enable this energy saving phenomenon is largely not well understood. Understanding this mechanism and creating better superconductors is essential for technological application, because currently superconductivity is largely a low-temperature phenomenon, with critical temperatures for superconductors being similar to the extremely low temperatures found on Mars or even in the coldest regions of outer space. Through this award, funded by the Solid State and Materials Chemistry as well as the Condensed Matter Physics programs in the Division of Materials Research at NSF, Freedman's research team engages in a theory-inspired search for new superconductors of a specific type, which could enable fundamental insight into the mechanism of superconductivity. Her team uses high-pressure synthesis to access new compounds that have long eluded chemists. This work enables interdisciplinary training for graduate students and postdoctoral fellows, where they benefit from the scientific intersection of solid-state chemistry, physics and geophysics. Preparing graduate students to collaborate across fields strengthens the next generation of our scientifically engaged workforce.Part 2: Technical summary: The realization of high temperature superconductivity would be a transformative advance, with implications across NSF directorates ranging from improved medical imaging to fault tolerant power transmission. Thus far, the vast majority of new superconductors have been found either by serendipity, modification of known superconducting systems, or through the investigation of theoretically unlikely candidates. In stark contrast, the targeted synthesis of new systems is underdeveloped, owing to the inherent difficulty of predicting new superconducting materials. To enable rational progress, a clear design strategy is needed, which necessitates knowing the operative superconducting mechanism in a given class of superconductors. Freedman proposes the synthesis of the notably missing subclass of Fe-Bi pnictide superconductors via high-pressure synthesis. This work is motivated by Freedman's recent discovery of the first Fe-Bi bond in the solid-state, achieved through the application of high pressure and stabilized by the formation of Bi-Bi interactions. Through this award, funded by the Solid State and Materials Chemistry as well as the Condensed Matter Physics programs in the Division of Materials Research at NSF, Freedman's team characterizes novel materials both through in situ and bulk X-ray diffraction and spectroscopic methods. Materials are physically probed via magnetometry, resistivity, and heat capacity measurements. The aggregate of these data provides insight into the mechanism of superconductivity, and possible structure-function correlations. Creating and understanding different superconductors offers promise for true discovery within this complex field. The realization of a new class of superconductors would foster collaborations across the sciences and enable a deeper understanding of superconductivity. Superconductors also have tremendous potential for societal impact, ranging from MRI instrumentation to increased power transmission through the electric grid.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.