A structural approach of the flux effect on blue phosphor BAM: Eu (BaMgAl_(10)O_(17):Eu~(2+))

摘要

In the aim of understanding the relations between the spectroscopic properties of blue phosphor BaMgAl_(10)O_(17):Eu~(2+) and its crystal structure, microstructure and chemical composition, three fluoride fluxes (LiF, MgF_2 and NH_4F) have been added before final thermal treatment and their effect analyzed. LiF changes the polycrystalline and spherical grains into hexagonal platelets without significant cations exchange and improves the luminescence. NH_4F and MgF_2 only have a limited effect, the former because of its low point of decomposition, the latter because of the formation of spurious MgAl_2O_4 that reduces the luminescence. In a general way, re-crystallization results in variations of the dopant distribution between the three host sites of the structure. Chromaticity is only faintly affected, but important variations of the absorption and excitation spectra are observed, allowing a strong increase of photoluminescence intensity under near-UV excitation.