M. Segura Guererro, A. Karati, T. Parida, H. Parmar, D. Prodius, I.C. Nlebedim
Ames National Laboratory,
United States
Keywords: rare earth fluorides, REMAFS technology, metallization, phase evolution, thermodynamic stability, ternary fluoride systems, metal-making
Summary:
This presentation will explore the phase evolution of Na-RE-F and K-RE-F (where RE = rare earth elements) to identify process windows that can be leveraged to enhance metal-making yield and purity. Ternary rare earth fluorides, M-RE-F (where M = Li, Na, K), exhibit a compelling combination of optical, electronic, and chemical properties [1]. These materials are used in applications such as photonics, biomedical imaging, solid-state lasers, scintillators, and catalysis. We recently reported the use of Na-RE-F as a feedstock for rare earth metal making and have since begun scaling the process through the REMAFS (Rare Earth Metals via Alternative Fluoride Salts) technology. It was reported that changes in the structural and physical properties of M-RE-F impacted their optical properties [2]. Therefore, to ensure robust control of metal-making processes as the technology scales, a deeper understanding of the phase evolution and thermodynamic stability of Na-RE-F, relative to other M-RE-F systems, is essential. This presentation will compare the structural, chemical, and thermal properties of Na-RE-F and K-RE-F across light (LREE), medium (MREE), and heavy (HREE) rare earth elements. We will demonstrate how phase evolution in both Na-RE-F and K-RE-F systems is affected by variations in precursor composition, processing temperature, and duration. The higher solubility of precursor for K-RE-F, compared to Na-RE-F, could support scalability. Ultimately, this work will not only support the continued development of the REMAFS metal-making technology but also inform the identification of other technologies that could benefit from the unique behavior of the M-RE-F salt system. Acknowledgement: This research was funded by the Critical Materials Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Materials and Manufacturing Technologies Office (AMMTO). The work was performed at Ames National Laboratory, operated for the U.S. Department of Energy by Iowa State University of Science and Technology under Contract No. DE-AC02-07CH11358. References 1. Fedorov, P. Systems of alkali and rare-earth metal fluorides. Russ. J. Inorg. 44 (1999) 1703-1727. 2. Sharma, R.K., Mudring, A.-V., Ghosh, P. Recent trends in binary and ternary rare-earth fluoride nanophosphors: how structural and physical properties influence optical behaviour. J. Lumin., 189 (2017) 44-63.