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

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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.