Thermally stimulated color-tunable performance of Ca3Ga4O9: Bi3+by co-doping with alkali metal ions

Thermally stimulated color-tunable persistent luminescent materials can serve in many practical applications. Integrating color-tunable luminescence into a stable charge carrier trapping phosphor is a promising strategy but remains a challenge. In this work, by co-doping with alkali metal ions, Ca2.90Ga4O9: 5 mol% Bi3+, 5 mol% A+ (A(+)= Li+, Na+, K+) phosphors show noticeable thermal stimulated luminescence color-tunability. Among these samples, the phosphor co-doped with Na+ shows a dramatic color variation with temperature from cyan (513 nm) at 99 degrees C to yellow (602 nm) at 237 degree celsius. Further studies confirm that the thermally stimulated colortunable feature of the sample is attributed to the interplay between dual traps and different emission centers. This work reports the dynamic color-tunable persistent luminescence under different temperatures in alkali metal ions co-doped gallate and provides a new perspective for the design of thermally responsive dynamic optical materials for the application of visual temperature warning or counterfeiting.