Photoluminescence and persistent luminescence properties of Lu3ScAl4-xGaxO12: Ce3+ ceramics

The application of most afterglow phosphors is greatly limited owing to the ultraviolet excitation. In this study, a series of cyan-emitting Lu(3)ScAl(4-x)GaxO(12):Ce3+ persistent luminescent ceramics which can be excited by visible-light were fabricated, and the photoluminescence and afterglow properties were investigated. The substitution of Ga for Al has tripartite effects on the optical properties of the garnet phosphors, namely making the emission spectrum blue-shift by reducing the crystal field strength, deteriorating the luminescence performance by facilitating thermal ionization from the 5d(1) level of Ce3+ to the conduction band of the host, and inducing afterglow by generating a series of quasi-continuous distribution of traps. It is found that the Lu(2.99)Ce(0.01)ScAl(4-x)GaxO(12) ceramics with Ga content (x) around 2.5 can be efficiently excited by sunlight or indoor/outdoor w-LEDs, and produce bright and long-lasting afterglow that matches human scotopic vision well, thus providing sufficient light intensity for identification or evacuation in the darkness.