Mechanochemical synthesis of mixed-ligand europium β-diketonates with nitrogen-containing neutral ligands

The solid-phase reaction between europium salts of β-diketones and nitrogen-containing neutral ligands in a planetary mill produces luminescent mixed-ligand compounds Eu(β-dic)3 · D, where β-dic stands for dibenzoylmethane (DBM), benzoylacetone (BA), thenoyltrifluoroacetone (TTA), or benzoyltrifluoroacetone (BTFA); and D stands for 1,10-phenanethroline (Phen), 2,2-dipyridyl (Dipy), or diphenylguanidine (DPG). The mechanosynthesis and yield of lanthanide β-diketonates are studied as affected by the treatment parameters and the nature of the reagents. Powder X-ray diffraction demonstrates a staged course of the mechanochemical synthesis. Examination of formation-rate curves shows that grinding/stirring is the rate-controlling stage of the process. Thermogravimetric analysis (TGA) shows that the mechanosynthesis can proceed in the self-propagation mode. The relative luminescence intensity is determined as a function of treatment time. Particles of the mechanically activated mixture have sizes of 10–100 μm.