Ba₂GdF₇ Nanocrystals: Solution-Based Synthesis, Growth Mechanism, and Luminescence Properties

Pseudo-octahedrons of Ba₂GdF₇ were successfully synthesized through a solution-based method in a hydrothermal environment for the first time. The preferential adsorption of ethylene glycol (EG) molecules on the {111} planes contributed to the formation of the octahedral shape. Hydrazine was employed as the alkaline source to adjust the adsorption affinity of EG and the hydrolysis rate of NaBF₄ (fluorine supply), thereby controlling the morphology and phase structure. A series of contrast experiments were conducted to investigate the growth mechanism of the Ba₂GdF₇ nanocrystals. As a proof-of-concept experiment, Eu³⁺, Tb³⁺, Dy³⁺, and Yb³⁺/Er³⁺ ions were doped to demonstrate the potential of the Ba₂GdF₇ crystals as host material for phosphors.