Piezoelectrically-induced stress-luminescence phenomenon in CaAl2O4:Eu2+

Piezoelectrically-induced stress-luminescence in the CaAl2O4:Eu2+ was investigated. Blue light that was visible to the naked eye could be observed in the dark when a pulse force of similar to 7.7 kN was applied to the sample. The intensity of the stress-luminescence strongly depended on the magnitude of the applied force during a pulse cycle. The intensity decreased with repetitive application of pulse stress and was completely recovered after irradiation with ultraviolet light. It is suggested that the stress-luminescence effect in CaAl2O4:Eu2+ arises from the piezoelectrically-induced de-trapping of the charge carriers. A CaAl2O4:Eu2+ ceramic that exhibits a stress-luminescence effect has potential applications in smart stress optically-sensing devices. (C) 2015 Elsevier B.V. All rights reserved.