Carlos R. García
The photocatalytic activity of Bismuth-codoped Sr4Al14O25:
Eu2+, Dy3+ persistent phosphors is studied by monitoring the
degradation of the blue methylene dye UV light irradiation.
Powder phosphors are obtained by a combustion synthesis
method and a postannealing process in reductive atmosphere.
The XRD patterns show a single orthorhombic phase
Sr4Al14O25: Eu2+, Dy3+, Bi3+ phosphors even at high Bismuth
dopant concentrations of 12 mol%, suggesting that Bi ions
are well incorporated into the host lattice. SEM micrographs
show irregular micrograins with sizes in the range of 0.5–
20 lm. The samples present an intense greenish-blue fluorescence
and persistent emissions at 495 nm, attributed to the
5d–4f allowed transitions of Eu2+. The fluorescence decreases
as Bi concentration increases; that suggest bismuth-induced
traps formation that in turn quench the luminescence. The
photocatalytic evaluation of the powders was studied under
both 365 nm UV and solar irradiations. Sample with 12 mol
% of Bi presented the best MB degradation activity; 310 min
of solar irradiation allow 100% MB degradation, whereas
only 62.49% MB degradation is achieved under UV irradiation.
Our results suggest that codoping the persistent phosphors
with Bi3+ can be an alternative to enhance their