Optical Energy Storage Properties of (Ca1−xSrx)2Si5N8: Eu2+, Tm3+ Solid Solutions

While the reddish-orange emitting phosphors M 2 Si 5 N 8 :Eu 2+ (M = Ca, Sr) have been intensively investigated as potential materials for white-light-emitting diodes, in this study, optical energy storage properties of (Ca 1− x Sr x ) 2 Si 5 N 8 : Eu 2+ , Tm 3+ ( x = 0–1) solid solutions were tuned by cation substitution, which was commonly used to tune color point for improving w-LEDs. Partial substitution of either Ca by Sr or Sr by Ca resulted in a redshifted Eu 2+ emission which had a demarcation point at x = 0.5. Furthermore, the (Ca 1− x Sr x ) 2 Si 5 N 8 : Eu 2+ , Tm 3+ materials exhibited similar persistent- and photostimulated luminescence behaviors with a maximum intensity at about x = 0.2. Such optical energy storage characters of the samples were attributed to the more appropriate trap depths (322–333 K) and higher density of energy level traps indicated by the thermoluminescence analysis.