Solution combustion synthesis of bluish-green BaAl2O4: Eu2+, Dy3+ phosphors

Bluish-green phosphors based on Eu and Dy-doped BaAl2O4 were prepared by solution combustion synthesis, without any additional annealing step, with a view to obtain high intensity of the emitted light and long afterglow. The mean crystallite size of the combustion-synthesized samples varied between 72 and 82 nm and the BET surface area was around 1.4 m2/g. The emission spectra of the obtained samples present a single band with a maximum at 499 nm. Increasing the Eu2+ proportion in the samples leads to a slight increase of the emission intensity, whilst increasing the Dy3+/Eu2+ ratio from 0/1 to 3/1 contributes to a sharp increase of the emission band intensity. The samples containing Dy3+ show significantly improved afterglow as compared to the sample doped only with Eu2+ and the wavelength of the emitted radiation remains the same. Supplementary annealing (air atmosphere) of the samples obtained from the combustion reaction was found to lead to a deterioration of the optical properties, as a consequence of reducing the concentration of structural defects.