Luminescent properties of Cr3+ doped Sr4Al14O25: Eu/Dy blue–green and red phosphor

Cr3+ doped Sr4Al14O25: Eu2+/Dy3+ persistent phosphor was synthesized for the first time by cheap, easy and efficient combustion method. Persistent phosphorescence in blue–green (495 nm) by Eu2+ and in red (695 nm) by Cr3+ was observed in this phosphor. The persistence time for blue–green emission is over 10 h but for red emission, it’s comparatively short. Red phosphorescence is performed through the persistent energy transfer from Eu2+ to Cr3+, converting the blue–green to red. The energy transfer rate increases on increasing the Cr3+ ions concentration and reach maximum at 4 at%. The comparative results revealed that the relatively regular morphology, smaller particle size and narrow size distribution can be achieved for the phosphor synthesized by the combustion method but the emission intensity is a bit poor, probably, due to low crystallinity. The phosphor after post annealing at 1300 °C showed higher emission intensity.