Collaborative Research: Rare Earth Materials Under Extreme Conditions

Brown University, Providence RI

Investigators

Abstract

Non-technical summary Rare earths are a group of chemical elements used extensively in batteries, cell phones, protective coatings, and high melting ceramics. Their stability and suitability for such applications are governed by their physical, electrical, magnetic, and thermodynamic properties, all of which are closely related to their structure. With support from the Ceramics Program in NSF’s Division of Materials Research, this project brings together computational theory and experimental structural and thermodynamic measurements to provide fundamental data and predictive understanding of the behavior of high-melting solid rare earth compounds containing oxygen, nitrogen, and carbon. The experiments are guided by computational predictions of stability and structure made by state-of-the art physical theory and machine learning. High pressure is used as a tool to discover and synthesize new rare earth materials. Specialized high temperature calorimetric techniques measure thermodynamic properties. The thermodynamic data will be made available in a database for use by both academic and industrial scientists. The new knowledge obtained enables future design of more efficient and earth-friendly materials and devices containing rare earth elements. Additionally, students are trained through this project in a variety of techniques, preparing them for careers in many fields, including materials science, ceramics, semiconductor technology, and aerospace science. Technical summary Continuing a long-standing collaboration between experimental and computational scientists, this project, supported by the Ceramics Program in NSF’s Division of Materials Research, focuses on the thermodynamic and structural properties of refractory rare earth containing ceramic materials. Computations using ab initio thermodynamics at high temperature and pressure combined with machine learning approaches will guide synthesis experiments at atmospheric and high pressures. High pressure samples are synthesized in a multi-anvil apparatus at Arizona State University (ASU). Thermodynamic properties are determined by oxide melt solution calorimetry, high temperature scanning calorimetry, and drop and catch calorimetry. High temperature phase transitions are studied by synchrotron diffraction techniques. Specific systems of interest include rare earth monoxides, oxycarbides, and sesquioxides, with emphasis on their structure and properties at high temperature and pressure. A database of thermodynamic properties will be developed and disseminated. Thereby thermodynamic data will be made available in a database for use by both academic and industrial scientists. The new knowledge obtained enables future design of more efficient and earth-friendly materials and devices containing rare earth elements. Additionally, students are trained through this project in a variety of techniques, preparing them for careers in many fields, including materials science, ceramics, semiconductor technology, and aerospace science. 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.