Electronic Instabilities by Design: Defining Pathways for Diffusing Electrons and Ions in Vanadium Oxide Bronzes

第一部分：？？非技术性总结现代技术的许多方面，从计算机芯片到电池，都依赖于在固体长度上移动电荷，无论是电子还是离子。精确控制离子和电子的流动对于这些技术非常重要，这取决于材料中原子的结构排列所定义的路径以及原子结合在一起的方式。该项目由NSF材料研究部的固态和材料化学计划资助，探索了在一种多功能化合物（由钒，氧和可变的第三种金属原子组成）中重新排列原子和改变路径的方式改变电子和离子的流动。通过调整原子之间的距离和管道的宽度，研究人员可以使材料绝缘，金属，或使其达到一个点，当施加外部刺激时，它可以在绝缘和金属行为之间切换。这些材料对于设计处理信息的新方法具有极大的意义。或者，调整离子存储和移动的管道有望设计出新型电池。 因此，该项目通过解开基本机制和指导电子和储能新材料的设计来促进国家繁荣和福利。了解原子需要连接以实现电荷流的有效路径的特定方式，为创造新的精确设计的化合物铺平了道路，这些化合物在可调电导和存储离子的能力方面表现出前所未有的功能。为了进一步推动美国在教育领域的全球领导地位的目标，首席研究员通过暑期实习计划和研讨会吸引了不同群体的学生参与他的研究，重点是从社区学院转学的学生。??第二部分：？？技术总结？当电子和空穴在扩展的固体中传播时，电荷载流子的速度、能量和有效质量由它们穿过的特定路径决定。通过原子结构的特定改变来精确和连续地调节轨道重叠和调制带宽的能力是固体化学和物理学中长期期望的目标，但是由于在独立控制结构和组成方面的困难，在实践中非常难以实现。该项目由NSF材料研究部的固态和材料化学计划资助，旨在通过改变组成，框架连接性和阳离子化学计量，使用具有分子式MxV2O5（其中M表示阳离子和x其化学计量）的化合物的多功能调色板精确定义电子和离子传导途径。该项目包括两个重点：第一个重点是开发基于结构，成分和化学计量调制的电子电导率调整设计规则，重点是设计处于电子跃迁尖端的新材料。第二个推力是集中在设计嵌入主机的锂，镁，钙，铝离子的基础上，系统地了解特定的结构图案，允许每个阳离子的扩散。这两个重点汇集了理论，合成，平均和局部结构的表征，电子结构的测量，以及设计新的电子相关材料和多价插入阴极的描述符的搜索。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

PART 1:?? NON-TECHNICAL SUMMARYMany aspects of modern technology, spanning the range from computer chips to batteries, rely on moving charge, either electrons or ions, across the length of solids. Precisely controlling the flow of ions and electrons is of great importance for these technologies, and it depends on the pathways defined by the structural arrangement of atoms within the material as well the manner in which the atoms are bonded together. The project, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, explores the way in which rearranging atoms and changing pathways within a versatile class of compounds (built from atoms of vanadium, oxygen, and a variable third metal) alters the flow of electrons and ions. By adjusting the distance between atoms and the width of the conduits, the researchers can make a material insulating, metallic, or bring it to a point where it can be switched between insulating and metallic behavior when applying external stimuli. Such materials are of great interest for designing new ways to process information. Alternately, tuning conduits for storage and movement of ions holds promise for enabling the design of new types of batteries. As such, the project advances national prosperity and welfare by unravelling basic mechanisms and guiding the design of new materials for electronics and energy storage. Understanding the specific manner in which atoms need to be connected to realize effective paths for charge flow paves the way to creating new precisely designed compounds exhibiting unprecedented function in terms of tunable electrical conductance and the ability to store ions. In order to further the objective of US global leadership in education, the principal investigator engages a diverse group of students in his research through summer internship programs and workshops, with an emphasis on students transferring from community colleges. ??PART 2:?? TECHNICAL SUMMARY?As electrons and holes propagate across extended solids, the velocity, energy, and effective mass of the charge carriers are determined by the specific pathways that they traverse. The ability to precisely and continuously tune orbital overlap and modulate bandwidths through specific alterations of atomistic structure is a long-desired goal in the chemistry and physics of solids, but it is exceedingly difficult to achieve in practice given difficulties in independently controlling structure and composition. The project, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, seeks to precisely define electronic and ionic conduction pathways using a versatile palette of compounds with the formula MxV2O5 (where M denotes a cation and x its stoichiometry) by alteration of composition, framework connectivity, and cation stoichiometry. The project comprises two thrusts: the first thrust is focused on developing design rules for tuning electronic conductivity based on modulation of structure, composition, and stoichiometry with an emphasis on designing new materials that are at the cusp of undergoing electronic transitions. The second thrust is focused on designing intercalation hosts for Li-, Mg-, Ca-, and Al-ions based on a systematic understanding of specific structural motifs that allow for diffusion of each of the cations. Both thrusts bring together theory, synthesis, characterization of average and local structure, measurements of electronic structure, and the search for descriptors to design new electron correlated materials and multivalent insertion cathodes.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.