Photoluminescent material with long afterglow is a kind of energy storage material that can absorb both ultraviolet (UV) and visible lights from sunlight, and gradually releases the energy in the dark at a certain wavelength. These sorts of materials have great potential for various device applications and have been widely studied by many researchers. In recent years, it has also been reported that 2SrO.3Al2O3/Eu 2+ and 4SrO.7Al2O3/Eu 2+ phosphors as green and blue emitters have even higher quantum efficiencies. To determine the initial particle size effect on the phosphorescence behaviour, Eu2+ /Dy 3+ doped Sr4Al 14O25 phosphors were synthesised by mixing 4SrO and 7Al2O3 with a flux (H3BO3) through high temperature solid state reaction method under weak reducing atmosphere. Such an influence on the crystalline structure and emission colour of phosphorescent pigments was studied by means of X-ray diffraction, scanning electron microscope (SEM), particle size analysis, excitation and emission spectroscopy. The results showed that the emission wavelength of the phosphorescence pigments shifted from green to blue region due to the decrease in average particle sizes of the phosphor batches, forming different types of strontium aluminate crystals. © 2012 Institute of Materials.