Mild Hydrothermal Crystal Growth Strategies for Complex Inorganic Metal Fluorides

Inorganic metal fluorides have been investigated for their interesting magnetic and optical properties, their electrochemical behavior, and their ionic conductivity. Fluoride materials can accommodate metals in very low oxidation states, which can be advantageous for designing new magnetic materials. Specifically, mixed metal fluorides incorporating transition metal cations often exhibit interesting magnetic behavior, such as frustrated magnetism. However, many challenges are encountered during the synthesis of such fluoride materials, including the inability to perform reactions under ambient conditions and the involvement of toxic gases for fluorination during solid-state reactions. Therefore, solution growth techniques such as mild hydrothermal synthesis are currently utilized for synthesizing fluoride materials. The use of hydrofluoric acid as a solvent and a mineralizer enhanced the capabilities of the mild hydrothermal synthesis for targeting various transition metal fluorides. This thesis concentrates on developing synthetic strategies to obtain mixed transition metal fluorides with geometrically frustrated magnetic behavior and extending the crystal growth to rare-earth fluorides under hydrothermal conditions. Additionally, it focuses on exploring the relationships between different crystal structure types to better understand the interesting magnetic behavior observed in mixed transition metal fluorides.