CAREER: Polar Ordering in Low-Dimensional Perovskites and Its Control via Colloidal Processing

Gabriel Caruntu获得了大分子，超分子和纳米化学（MSN）和EPSCoR计划的支持，并获得了一项职业奖，该奖项调查了亚微米尺度下铁电性的生存和极化的几何有序性。尽管在过去的几十年里铁电陶瓷的技术重要性大大增加，但这些仍然难以捉摸。该CAREER项目旨在通过关联其结构，振动，电子和其他宏观性质之间的密切关系，开发纳米级钙钛矿中极性有序的稳健预测方法。为此，Caruntu教授设计了一个全面的实验框架，以研究原子水平扭曲，相变，微观结构演变，极化反转和开关机制之间的复杂相互关系，使用无聚集体的单分散钙钛矿纳米晶体作为模型系统。最终的目标是预测在何种程度上的极性有序可以诱导和操纵在纳米尺度上通过微调的组合物，表面结构，横向尺寸和三维限定的钙钛矿的空间有序。从这项工作中获得的知识将在概念上拓宽纳米级铁电体的领域，从而提供新的见解，在这些材料的极性排序的尺寸效应和表面曲率。这可能会导致具有可编程铁电，介电和压电特性的智能钙钛矿材料的实际设计技术的改进。此外，这对于理解极性畸变和表面结构如何影响自发极化以及原子偶极子在铁电钙钛矿量子点中的组织方式至关重要。因此，这项研究的成功有望将这种方法扩展到其他金属氧化物系统，并激发这些纳米结构在能量收集、水分解和其他能源和/或环境相关技术中的应用。考虑到钙钛矿基材料的技术重要性，该项目的社会和教育影响很大。该小组建立的实验方法将为开发具有可控形状/形态和可预测性质的铁电基功能纳米材料奠定坚实的基础。该研究本质上是跨学科的，需要材料和计算化学，器件设计，振动光谱，电子全息，扫描探针显微镜和胶体和表面科学的专业知识。除了这些领域之外，该项目的成果还将对能源转换、压电和纳米材料设计等相互关联的学科产生重大影响。该项目的教育内容丰富多样。研究和教育部分的整合将产生广泛的外联和教育活动，旨在鼓励年轻学生考虑化学、材料科学和纳米技术方面的教育和职业，向高中生、K-12教师、本科生和研究生介绍铁电体跨学科领域，并扩大代表性不足的少数群体的参与。学生将接受纳米材料合成，物理表征，数据分析和钙钛矿纳米结构物理特性测量相结合的培训。这项工作还将导致开发新的课程和协同的本科和高中课堂模块，展示钙钛矿纳米材料集成到不同技术应用中的广泛可能性。该项目的教育目标是培养本科生和研究生未来的材料科学工作，既通过指导学生从大一到研究生水平的研究，并通过将研究整合到本科和研究生水平的课程。

Gabriel Caruntu is supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) and EPSCoR programs in a CAREER award investigating the survival of ferroelectricity and geometrical ordering of the polarization at sub-micrometer length scales. These still remain elusive despite the tremendous increase in the technological importance of ferroelectric ceramics in the past decades. This CAREER project is aimed at developing a robust predictive methodology of polar ordering in nanoscale perovskites by correlating the intimate relationship between their structural, vibrational, electronic and other macroscopic properties. To this end, Prof. Caruntu designed a comprehensive experimental framework to investigate the complex interrelations between the atomic level distortions, phase transitions, evolution of microstructures, polarization reversal and switching mechanisms using aggregate-free monodisperse perovskite nanocrystals chosen as model systems. The ultimate goal is to predict the extent to which the polar ordering can be induced and manipulated at nanometer scales by finely tuning the composition, surface structure, lateral dimensions and spatial ordering of tri-dimensionally confined perovskites. The knowledge obtained from this work will conceptually broaden the field of nanoscale ferroelectrics, thereby providing new insights into size effects and surface curvature on the polar ordering in these materials. This can potentially result in the improvement of the actual design technologies in smart perovskite materials with programmable ferroelectric, dielectric and piezoelectric properties. Also, this is critical for understanding how the polar distortion and the surface structure influence the spontaneous polarization and the way the atomic dipoles are organized in ferroelectric perovskite quantum dots. Success in this research is therefore expected to extend this methodology to other metal oxide systems and inspire the implementation of these nanostructures in energy harvesting, water splitting and other energy and/or environmental-related technologies. The societal and educational impacts of this project are strong, taking into account the technological importance of perovskite-based materials. The experimental methodology established in the group will lay a solid foundation for the development of ferroelectric-based functional nanomaterials with controlled shape/morphology and predictable properties. The research is by nature inter-disciplinary, requiring expertise from materials and computational chemistry, device design, vibrational spectroscopy, electron holography, scanning probe microscopy and colloid and surface science. Besides these fields, the project's outcomes will have a significant impact on inter-related disciplines such as energy conversion, piezoelectricity and nanomaterials design. The educational component of this project is strong and varied. The integration of research and educational components will generate broad outreach and educational activities aimed at inspiring young students to consider education and careers in chemistry, materials sciences and nanotechnology, introducing high school students, K-12 teachers, undergraduate and graduate students to the interdisciplinary field of ferroelectrics and broadening the participation of underrepresented minorities. Students will be trained in a combination of nanomaterials synthesis, physical characterization, data analysis and measurement of the physical proprieties of perovskite nanostructures. The work will also lead to the development of new courses and synergistic undergraduate and high school classroom modules that demonstrate the broad possibilities of perovskite nanomaterials for integration into different technological applications. The educational objective of this project is to train undergraduate and graduate students for future jobs in materials science, both through mentoring students from freshman to graduate level in research and by integrating the research into undergraduate and graduate level courses.