CAREER: Understanding disorder, defects, and dielectric properties of entropy-stabilized oxides

非技术描述：新材料的发现和发展是微电子技术革命的基础。最近，一个新的材料领域出现了，它利用了大量的化学和结构无序对其有利。该项目将使用原子尺度的结构和化学无序工程来发现和理解这些新材料，以实现前所未有的功能。该项目旨在利用最先进的薄膜沉积技术和原位结构表征以及原子到微米尺度的成像技术来了解结构和化学无序的多组分氧化物的稳定性、其复杂结构以及无序导致新的物理性能的方式。这项研究的结果有望为实现新的氧化物材料和无序-性质关系提供新的见解。这个项目的学生正在接受材料合成和材料结构和介电性能测量方面的专业培训。毕业后，学生有资格在学术界和工业领域就业--特别是与微电子相关的领域。这项研究与教育活动相结合，旨在吸引大学预科学生参与，并为高中阶段教授的物理课程建立一种新的教学法。正在开发课程组成部分，利用陶瓷的介电特性和应用，将科学实践和从原子到宏观的尺度思维引入高中课堂。这项努力是将教师聚集在一起接受培训，将这些新内容融入他们的教学中。正在通过一年两次的调查和面谈来评估这些活动的影响和优点。技术细节：功能化的缺陷和无序可以解锁陶瓷前所未有的特性。为了促进这一功能，该项目寻求全面了解、表征、控制和预测不同长度范围的紊乱。在氧化物中，磁性和电性与其立体化学和电子结构密切相关。无序的引入，无论是化学上还是结构上，都可能导致对称性破坏、掺杂以及与紧急和巨大的物理性质相关的受挫的键和电子配置。由大的构型无序稳定的多组分氧化物的发现，即所谓的熵稳定的氧化物，创造了一种独特的物质状态，在这种状态下，可以实现源于固有的化学和结构无序的增强的功能性质。本项目的目标是：1)利用实时表征来解决沉积过程中吸附原子的弛豫和晶体结构的演变，以了解氧化物薄膜中的熵稳定机制；2)利用透射电子显微镜、X射线光电子能谱、X射线衍射和介电光谱，从原子到宏观尺度上的探针无序、缺陷、电荷和成分不均匀；以及3)了解导致熵稳定氧化物的异常应变弛豫、大的结构变化和巨大的介电性能的微观结构机制。预计结果将阐明对驱动微结构的稳定、演化和无序的热力学和动力学因素、缺陷形成及其对介电性能的影响的新的科学理解。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。

NON-TECHNICAL DESCRIPTION: The discovery and development of new materials underlies technological revolutions in microelectronics. Recently, a new materials field has emerged that harnesses large chemical and structural disorder to its advantage. This project will use atomic-scale engineering of structural and chemical disorder to discover and understand these new materials to achieve unprecedented functionalities. This project aims to leverage state-of-the-art film deposition with in-situ structural characterization and atomic-to-micron scale imaging techniques to understand the stabilization of structurally and chemically disordered multicomponent oxides, their complex structure, and the ways disorder induces novel physical properties. The results of this research are anticipated to provide new insights toward realizing new oxide materials and disorder-property relationships. Students in this project are receiving professional training in materials synthesis and the measurement of structural and dielectric properties of materials. Upon graduation, students are qualified for employment in academia and industrial fields - especially those related to microelectronics. This research is integrated with educational activities to engage pre-college students and establish a new pedagogy for physical science classes taught at the high school level. Curriculum components are being developed to introduce scientific practices and atomic-to-macroscopic scale thinking into the high-school classroom using the dielectric properties and applications of ceramics. The effort is bringing teachers together to receive training to integrate these new components into their teaching. The impact and merit of these activities is being assessed using biannual surveys and in-person interviews. TECHNICAL DETAILS: Functionalizing defects and disorder can unlock unprecedented properties in ceramics. To facilitate this functionality, this project seeks to comprehensively understand, characterize, control, and predict disorder across length scales. In oxides, the magnetic and electronic properties are strongly correlated to their stereochemistry and electronic structure. The introduction of disorder, chemically or structurally, can lead to symmetry breaking, doping, and frustrated bond and electronic configurations that have been associated with emergent and colossal physical properties. The discovery of multicomponent oxides stabilized by a large configurational disorder, so called entropy-stabilized oxides, creates a unique state of matter where enhanced functional properties stemming from the inherent chemical and structural disorder can be realized. This project aims to: 1) utilize real-time characterization to resolve adatom relaxation and evolution of crystal structure during deposition to understand mechanisms of entropy stabilization in oxide thin films, 2) probe disorder, defects, and charge and compositional non-uniformities from atomic- to macro-scale using transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and dielectric spectroscopy, and 3) understand the microstructural mechanisms that give rise to the anomalous strain relaxation, large structural changes, and colossal dielectric properties of entropy-stabilized oxides. It is anticipated that results will elucidate new scientific understanding of the thermodynamic and kinetic factors that drive stabilization, evolution and disorder of the microstructure, defect formation, and their consequences on dielectric properties.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.