CAREER: Structure Property Relationships in BiFeO3: A Defect Chemistry Approach

非技术描述：将开发一种新的方法，允许具有挥发性成分的薄膜复合氧化物的组成控制。该技术将在铋铁氧体中得到证明，铋铁氧体是一种晶体固体，具有当前技术感兴趣的材料特性。这种新的加工方法将允许在纳米尺度上显著减少与成分相关的缺陷，并在此过程中显著改善电性能。首要的兴趣是铋铁氧体耦合电场和磁场的能力：这种能力被广泛认为是新一代多功能传感、驱动和数据存储设备的基石。例如，提供前所未有的同时感应电、声和磁场的设备将被启用，并且对远程监视等应用极具吸引力。只有实现这项研究提供的改进，才能充分利用这些机会。在整个项目期间，至少有一名研究生和两名本科生将积极参与，并且每个夏季学期，该项目将支持材料科学教育推广活动。这项活动将包括为K-12科学教师举办学习讲习班，重点是使K-12教育工作者能够将材料科学原理，特别是纳米尺度的材料科学原理纳入他们的课程。技术细节：该计划探索铁电薄膜的缺陷化学，晶体结构和电性能之间的基本关系。本研究的基础涉及一种新的薄膜加工方法，通过气相平衡控制BiFeO3的阳离子化学计量和点缺陷。这代表了对薄膜加工科学的基本贡献，因为几乎所有的商业和军用电子材料都依赖于部分通过缺陷平衡工程进行性能优化。电陶瓷薄膜还没有开发出类似的复杂能力，因此薄膜性能工程的主要机会尚未开发。所提出的综合技术将在许多系统中实现这种优化，这些系统有望实现显著的性能改进，并洞察与缺陷相关的现象。在他们的研究过程中，参与的研究生和本科生将开发一种先进的气相/凝聚相平衡方法，用于主动调整缺陷平衡。在此过程中，他们将确定薄膜中的缺陷平衡-性质关系，这代表了材料科学的重要进步，特别是在纳米尺度上，缺陷的影响变得更加明显。

NON-TECHNICAL DESCRIPTION: A new methodology allowing composition control of thin film complex oxides with a volatile constituent will be developed. This technique will be demonstrated in bismuth ferrite, which is a crystalline solid having material properties of current technological interest. This new processing approach will allow dramatic reduction composition-related defects at the nanoscale, and in doing so, provide for dramatic improvements in the electrical properties. Of premier interest is the ability of bismuth ferrite to couple electrical and magnetic fields: this capability is widely regarded as the cornerstone of a new generation of multifunctional sensing, actuating, and data storage devices. For example, devices offering unprecedented and simultaneous sensing of electrical, acoustic, and magnetic fields will be enabled, and are extremely attractive for applications such as remote surveillance. These opportunities can be fully harnessed only if the improvements offered by this research are realized. Through the duration of this program, a minimum of one graduate student and two undergraduate students will be active participants, and each summer semester, this program will support a Materials Science educational outreach activity. This activity will involve learning workshops for K-12 science teachers, which focus on empowering K-12 educators to incorporate the Principles of Materials Science, specifically at the nanoscale, to their curriculum.TECHNICAL DETAILS: The proposed program explores fundamental relationships between defect chemistry, crystalline structure, and the electrical properties of ferroelectric thin films. The cornerstone of this investigation involves a novel thin film processing methodology controlling cation stoichiometry and point defects in BiFeO3 through gas-phase equilibrium. This represents a fundamental contribution to thin film processing science since nearly all commercial and military electronic materials rely on property optimization in part through defect equilibrium engineering. A similarly sophisticated capacity has not been developed for electroceramic thin films, thus a major opportunity in thin film property engineering remains untapped. The proposed synthesis technique will enable this optimization in numerous systems holding promise for dramatic property improvement, and insight into defect-related phenomena. In the course of their research, the participating graduate and undergraduate students will develop a cutting-edge gas-phase/condensed-phase equilibrium method for actively tuning defect equilibria. In doing so, they will identify defect equilibria - property relationships in thin films, which represents an important advancement in Materials Science, especially at the nanoscale, where the impact of defects becomes more pronounced.