Synthesis of M1-3xAl2O4:Eu2+x/Dy3+2x (M2+= Sr2+, Ca2+ and Ba2+) phosphors with long-lasting phosphorescence properties via co-precipitation method

The long afterglow fluorescent material of M1-3xAl2O4:Eu2+x/Dy3+2x (M2+ = Sr2+, Ca2+ and Ba2+) phosphors are successfully synthesized by calcining precursor obtained via co-precipitation method at 1300 oC for 4 h with reducing atmosphere (20% H2 and 80% N2. The phase evolution, morphology and afterglow fluorescent properties are systematically studied by the various instruments of XRD, FE-SEM, PLE/PL spectroscopy and fluorescence decay analysis. The PL spectra shows that the Sr1-3xAl2O4:Eu2+x/Dy3+2x phosphors display vivid green emission at ~519 nm (4f65d1→4f7 transition of Eu2+) with monitoring of the maximum excitation wavelength at ~334 nm (8S7/2→6IJ transition of Eu2+), among which the optimal concentration of Eu2+ and Dy3+ is 15 at % and 30 at %, respectively. The color coordinates and temperature of Sr1-3xAl2O4:Eu2+x/Dy3+2x phosphors are approximately at (~0.27, ~0.57) and ~6700 K, respectively. On the above basis, the M0.55Al2O4:Eu2+0.15/Dy3+0.3 (M2+ = Ca2+ and Ba2+) phosphors is obtained by the same method. The PL spectra of these phosphors shows the strongest blue emission at ~440 nm and cyan emission at ~499 nm under ~334 nm wavelength excitation, respectively, which are blue shifted comparing to Sr1-3xAl2O4:Eu2+x/Dy3+2x phosphors. The color coordinates and temperatures of M0.55Al2O4:Eu2+0.15/Dy3+0.3 (M2+ = Ca2+ and Ba2+) phosphors are approximately at (~0.18, ~0.09)，~2000 K and (~0.18, ~0.42), ~11600 K, respectively. In this work, long afterglow materials of green, blue and cyan aluminates phosphors with excellent properties have been prepared, in order to obtain wide application in the field of night automatic lighting and display.