d-f luminescence of Ce^(3+) and Eu^(2+) ions in BaAl_(2)O_(4), SrAl_(2)O_(4) and CaAl_(2)O_(4) phosphors

摘要

Ce^(3+)and Eu^(2+)doped alkaline earth aluminates MAl_(2)O_(4)(M=Ca,Sr,Ba)were prepared by single-step combustion synthesis at low temperature(600°C).X-ray diffraction(XRD)analysis confirmed the formation of BaAl_(2)O_(4),CaAl_(2)O_(4),and SrAl_(2)O_(4).Photoluminescence spectra and optimal luminescent properties of Ce^(3+)and Eu^(2+)doped MAl_(2)O_(4) phosphors were studied.Relation between Eu^(2+)and Ce^(3+)f-d transitions was explained.Spectroscopic properties known for Ce^(3+)were used to predict those of Eu^(2+)by using Dorenbos’method.The values thus calculated were in excellent agreement with the experimental results.The preferential substitution of Ce^(3+)and Eu^(2+)at different Ba^(2+),Sr^(2+),Ca^(2+)crystallographic sites was discussed.The dependence of emission wavelengths of Ce^(3+)and Eu^(2+)on local symmetry of different crystallographic sites was also studied by using Van Uitert’s empirical relation.Experimental results matched excellently with the predictions of Dorenbos’and Van Uitert’s models.