Development of Approaches to Mass Synthesis of Luminescent Fluoride Nanomaterials

Mass synthesis techniques of photoluminescent β-NaRF4 (R=Y, Er–Lu) nanoparticles by utilizing “topdown” and “bottom-up” technological approaches have been optimized. Technological regimes for high-energy milling of β-NaRF4 polycrystal ingots fabricated by melt directional crystallization have been developed for the synthesis of particles in the size range up to 100 nm with a mass yield of up to 2.5 g per technological process. The subsequent heat treatment of milling nanoobjects in the presence of appropriate trifluoroacetate precursors in a high-boiling organic solvent medium significantly improves their photoluminescent characteristics due to surface passivation. The synthesis of β-NaRF4 nanoparticles by heterogeneous crystallization on ultrafine seed crystals has been developed and optimized. This technique allows to stabilize the growth process and solve the observed synthetic difficulties determined by the polymorphism of this kind of compounds. The simplicity and efficiency of the proposed technology for the mass production of β-NaRF4 nanoparticles based on “heavy” R=Yb, Lu (up to 50 g per synthesis) with a complex “seed–core–shell” structure in a broad size range with controlled morphological and structural characteristics are demonstrated in detail.