Ultraviolet mechanoluminescence from SrAl2O4:Ce and SrAl2O4:Ce,Ho

Phosphors with ultraviolet (UV) mechanoluminescence (ML) SrAl2O4:Ce (SAOCe) and SrAl2O4:Ce,Ho (SAOHoCe) were reported in this letter. The results reveal that the ML emission band is located at 375 nm similar to photoluminescent (PL) peak, which indicates that ML is emitted from the same center of Ce3+ ions as PL. Furthermore, the addition of Ho3+ increases the UV ML intensity of SAOHoCe (56 nJ/load cycle) considerably [approximately two orders of magnitude greater than that of SAOCe (0.21 nJ/load cycle)]. The formation of many shallow traps (Ho3+-e(-)) may be responsible for this enhancement.