Structure and Function of Heteroanionic Materials

非技术总结21世纪的微电子和电池技术依赖于由过渡金属氧化物组成的部件，这些部件可以适应电子分布的可逆变化。该奖项支持对异阴离子材料基础科学的理论和计算研究，异阴离子材料是由氧以外的一个以上阴离子组成的化合物，如氮氧化物、氟氧化物和硫氧化物。这些化合物受益于氧化物材料的稳定性，但由于额外的二次阴离子，具有可调的电子、磁性和拓扑性质，允许更好地控制电子分布。该项目的目标是通过在晶体结构和阴离子化学之间建立联系，从理论、模拟和综合实验的耦合中，设计、发现和控制显示铁电性、金属-绝缘体转变和拓扑能带结构的异阴离子材料的性质。该项目利用基于量子力学的计算来建立既具有描述性又具有预测性的模型框架和知识。这些模型和方法可能扩展到异阴离子材料以外的材料，使具有不同电子功能的化合物能够前所未有地扩展到未来技术。学生的教学和培训与项目的发现能力也相互交织在一起，旨在通过公共外联活动、本科生和研究生课程开发以及让学生参与经验性和跨学科培训，扩大未被充分代表的学生对科学、技术、工程和数学学科的参与。通过与高中教师合作开发符合下一代科学标准的材料物理/工程模块，教育影响延伸到高中生。技术和技术复杂过渡金属氧化物因其性质广泛，从铁电到可极化氧化物负离子支持的高温超导，被用于各种技术。设计、发现和控制具有新颖性质和优异性能的新型过渡金属化合物，特别是那些具有多个阴离子(异阴离子材料)而不是多个阳离子(具有单一阴离子的同阴离子氧化物)的过渡金属化合物，对于当前和未来技术的持续发展至关重要。该奖项支持对氮氧化物、氟化物和硫氧化物等异阴离子材料基础科学的理论和计算研究。该项目的目标是实施和扩展异阴离子材料设计方案，以了解原子结构、阴离子顺序和新的电子和量子态上的能带结构之间的复杂相互作用，并开发具有高负离子材料所没有的优异功能和/或响应的新的异阴离子材料。该项目利用一种结合了群论技术、导数结构工具和密度泛函理论的计算策略来理解氮氧化物、氟氧化物和硫氧化物在三个推力下的电子和光学性质，重点放在(I)偏心函数的几何和化学控制；(Ii)探索材料发现的金属-绝缘体转变机制；以及(Iii)获得阴离子有序拓扑半金属的新途径。该项目将提供新的知识，以促进从多个阴离子衍生的具有可调电子态的材料的选择和设计。它通过推进基于结构的设计策略来控制电子性能，从而使社会受益，这可能导致发现用于低功率和大脑启发的微电子、透明光电子学和量子信息系统的可重构材料。此外，该项目的教育目标包括在多个层次对学生进行教学和培训，并扩大代表不足的学生参与STEM的范围。这些目标延伸到高中生，通过与高中教师合作开发符合下一代科学标准的材料物理/工程模块。这些努力将影响下一代劳动力，赋予学生和教师解决问题的技能，使他们在具有全球竞争力的职业生涯中取得成功。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。

NONTECHNICAL SUMMARYTwenty-first century microelectronic and battery technologies rely on components consisting of transition metal oxides that can accommodate reversible changes in the distribution of their electrons. This award supports theoretical and computational research on the fundamental science of heteroanionic materials, which are compounds consisting of more than one anion beyond oxygen such as oxynitrides, oxyfluorides, and oxysulfides. These compounds benefit from the stability of oxide materials, but have the added advantage of tunable electronic, magnetic, and topological properties owing to the additional secondary anion, which allows for greater control over the electron distribution.The project goals are to design, discover, and control the properties of heteroanionic materials displaying ferroelectricity, metal-insulator transitions, and topological band structures by establishing links between crystal structure and anion chemistry, profiting from a coupling of theory, simulation, and comprehensive experimentation. The project utilizes quantum-mechanical based calculations to establish model frameworks and knowledge that are both descriptive and predictive. These models and approaches may be expanded to materials beyond heteroanionic materials, enabling an unprecedented expansion of compounds with varying electronic functions for future technologies.The teaching and training of students and the discovery capabilities of the project are also interwoven and aimed at broadening participation of underrepresented students in Science Technology Engineering and Mathematics disciplines through public outreach events, through undergraduate and graduate curriculum development, and by involving students with experiential and interdisciplinary training. The educational impact extends to high-school students by developing materials physics/engineering modules that meet Next Generation Science Standards in concert with high school teachers.TECHNICAL SUMMARYComplex transition metal oxides are utilized in a variety of technologies owing to their properties ranging from ferroelectricity to high-temperature superconductivity supported by polarizable oxide anions. The design, discovery, and control of new transition metal compounds, particularly those with multiple anions (heteroanionic materials) rather than multiple cations (homoanionic oxides with a single anion), with novel properties and superior performance are crucial to the continued development of present and future technologies. This award supports theoretical and computational research on the fundamental science of heteroanionic materials such as oxynitrides, oxyfluorides, and oxysulfides.The project goals are to implement and extend a heteroanionic materials design scheme for understanding the complex interplay among atomic structure, anion order, and band structure on novel electronic and quantum states and to advance new heteroanionic materials exhibiting superior functionalities and/or responses not found in homoanionic materials. The project utilizes a computational strategy, which integrates group theoretical techniques, derivative-structure tools, and density functional theory, to understand the electronic and optical properties of oxynitrides, oxyfluorides, and oxysulfides within three thrusts focused on (i) geometric and chemical control of noncentrosymmetry for acentric function; (ii) probing metal-insulator transition mechanisms for materials discovery; and (iii) novel routes to anion-ordered topological semimetals. The project will deliver new knowledge to facilitate the selection and design of materials with tunable electronic states derived from multiple anions. It benefits society by advancing the repertoire of structure-based design strategies to control electronic properties, which could lead to discovery of reconfigurable materials for low-power and brain-inspired microelectronics, transparent optoelectronics, and quantum information systems. In addition, educational goals of the project include the teaching and training of students at multiple levels and broadening STEM participation by underrepresented students. These goals extend to high-school students by developing materials physics/engineering modules in concert with high school teachers that meet Next Generation Science Standards. These efforts will impact the next-generation workforce by endowing students and teachers problem-solving skills to be success in globally competitive careers.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.