EAGER: SUPER: Non-Hexagonal 2D Boride and Borocarbide Superconductors

本项目由材料研究部，教授。Kirill Kovnir， Kai Ming Ho和Vladimir Antropov和他们在爱荷华州立大学的研究小组将专注于发现新的高温超导体，这将极大地造福社会。高温超导体在环境压力下是稳定的，有可能在许多与能源有关的领域彻底改变现代技术：发电、透射、转换和运输。这种超导材料目前还无法获得。先前对传统超导体的广泛研究指出，基于轻元素（如氢、碳和硼）的系统是有希望的。在目前的项目中，计算和实验工作结合起来，在两种或两种以上过渡金属的层状硼化物和硼碳化物中寻找新的超导体。这些特殊的目标系统还没有得到充分的研究，并且有望通过金属或硼/碳取代来调整材料的性质。本研究将计算与实验相结合，为研究生研究人员提供多样化的训练。本项目所考虑的基本问题适用于新兴能源技术。所获得的知识和建立的方法可能适用于其他领域的功能材料开发。本项目由材料研究部支持，重点研究两种或两种以上过渡金属的非六方硼化物和硼碳化物中的高温超导体。不同过渡金属的组合允许实现基于5元和7元B环的层，为调整硼网络中的电子-声子相互作用提供了杠杆。寻找新的超导体开始于广泛的计算筛选三元和多金属硼化物和硼碳化物，这些硼碳化物含有至少两种不同的过渡金属，具有非六边形B或B- c层。结合自适应遗传算法和快速先进的机器学习算法，对大量硼化物和硼碳化物进行了筛选。用更高层次的理论评价了有希望的候选者，并利用DFT估计了与电子-声子超导性相关的性质（态密度、声子频率、电子-声子耦合）。利用离散傅立叶变换的结果，对选定的候选分子进行了实验合成和表征。实验反馈提供给结构优化和超导组，以进一步估计通过共价取代优化电子-声子相互作用的潜在方法，在过渡金属亚晶格（调整电子性质）和硼亚晶格（硼/碳取代调整声子相互作用）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYWith this project, supported by Division of Materials Research, Profs. Kirill Kovnir, Kai Ming Ho, and Vladimir Antropov and their research groups at Iowa State University will be focused on the discovery of novel high-temperature superconductors which will greatly benefit society. High-temperature superconductors which are stable at ambient pressure have the potential to revolutionize modern technology in many energy-related fields: generation, transmittance, transformation, and transportation. Such superconducting materials are currently unavailable. Extensive previous studies on conventional superconductors pointed to promise of the systems based on light elements, such as hydrogen, carbon, and boron. In the current project, computational and experimental efforts are joined to find novel superconductors among layered borides and borocarbides of two or more transition metals. These particular target systems are severely understudied, and hold promise for tuning of the materials properties by means of metal or boron/carbon substitutions. The proposed research integrates computational and experimental studies to provide diverse training for graduate student researchers. The fundamental issues considered in the project are applicable to emergent energy technology. The acquired knowledge and established methodology may be applicable for functional materials development in other areas. TECHNICAL SUMMARYThis project, supported by the Division of Materials Research, is focused on the discovery of high-temperature superconductors in non-hexagonal borides and borocarbides of two or more transition metals. A combination of different transition metals allowed for realization of layers based on 5- and 7-membered B rings providing a lever to tune electron-phonon interactions in the boron network. The search for new superconductors starts with the wide computational screening of ternary and multinary metal borides and borocarbides containing at least two different transition metals with non-hexagonal B or B-C layers. A combination of Adaptive Genetic Algorithm and fast advanced machine learning algorithms is used to screen a large number of boride and borocarbides. The promising candidates are evaluated by higher-level theory and the properties relevant for the electron-phonon superconductivity (density of states, phonon frequencies, electron-phonon coupling) are estimated using DFT. Using the DFT result, selected candidates are experimentally synthesized and characterized. The experimental feedback is provided both to structural optimization and superconductivity groups to further estimate potential ways of optimizing electron-phonon interaction by aliovalent substitutions, in both, transition metal sublattice (to tune electronic properties), and boron sublattice (boron/carbon substitutions to tune phonon interactions).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.