Phase formation in LaF3-NaGdF4, NaGdF4-NaLuF4, and NaLuF4-NaYF4 systems: Synthesis of powders by co-precipitation from aqueous solutions

- Five-fold NaF excess is required for precipitation of stoichiometric NaLuF4 phase.
- Continuous cubic solid solutions were precipitated in the NaYF4-NaLuF4 system.
- Hexagonal NaGdF4-type and cubic NaLuF4-type solid solutions phases were prepared.
- Formation of 3 phases has been observed in the LaF3-NaLuF4 cross-section.
- All synthesized phases are metastable (except hexagonal NaGdF4-based phase).