Stress-induced mechanoluminescence in SrAl2O4:Eu2+,Dy3+

Mechanoluminescent materials show promising applications to advance stress-sensing techniques, including no contact, full-field sensing and self-diagnosis structures. In this paper stress-induced mechanoluminescence (ML) in persistent phosphor, SrAl2O4:Eu2+,Dy3+ (SAO:ED), was studied. ML intensity under various loading and unloading conditions were investigated. Samples used are a composite of SAO:ED and epoxy resin. It was found that the ML signals could be only produced by dynamic stress, but not by static stress. Static stress did not change the decay process of the afterglow. Unloading stress from samples could also induce ML. Sensitivity of ML was found to be dependent on the delay time when applying the stress, and also dependent on the ratio of SAO to epoxy in the samples. A possible mechanism of stress-induced mechanoluminescence is discussed.