Blue–green afterglow of BaAl2O4:Dy3+ phosphors

• Afterglow can be achieved when Eu2+ is absent in the DyAl2O4:Dy3+ phosphors.
• The afterglow of DyAl2O4:Dy3+ phosphors is discernible to naked eyes for minutes.
• Dy3+ introduced trap centers are believed to be responsible for the afterglow.

Dy3+ doped barium aluminate (BaAl2O4:Dy3+) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of the absence of Eu2+ luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl2O4:Dy3+ phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl2O4:Dy3+ in the absence of Eu2+ provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl2O4:Dy3+ phosphors are discussed in terms of the Dy3+ ions introduced trap centers as well as luminescent centers in the crystal lattice.

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