Combustion synthesis of blue‐emitting submicron CaAl 4 O 7 :Eu 2+ , Dy 3+ persistence phosphor

Long persistence phosphor CaAl 4 O 7 : Eu 2+ , Dy 3+ were prepared by a combustion method. The phosphors were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), decay time measurement techniques and photoluminescence spectra (PL). The CaAl 4 O 7 : Eu 2+ , Dy 3+ phosphor showed a broad blue emission, peaking at 445 nm when excited at 341 nm. Such a blue emission can be attributed to the intrinsic 4f → 5d transitions of Eu 2+ in the host lattices. The lifetime decay curve of the Dy 3+ co‐doped CaAl 4 O 7 : Eu 2+ phosphor contains a fast decay component and another slow decay one. Surface morphology also has been studied by SEM. The calculated CIE colour chromaticity coordinates was (0.227, 043). We have also discussed a possible long‐persistent mechanism of CaAl 4 O 7 :Eu 2+ , Dy 3+ phosphor. All the results indicate that this phosphor has promising potential for practical applications in the field of long‐lasting phosphors for the purposes of sign boards and defence. Copyright © 2011 John Wiley & Sons, Ltd.