Enhanced blue mechanoluminescence of SrnMgSi2O5+n:Eu alkali-earth silicate induced by defective phase

Obvious enhancement of blue mechanoluminescence (ML) has been observed for SrnMgSi2O5+n:Eu (1 <= n <= 2) (SMSE) fabricated via systematically controlling the defective phases. The existence of defective phases affects not only the concentration of trap centers but also the structure of SMSE. The dependence between ML intensity and thermoluminescence integrated intensity showed that the trap centers created by defective phase play an important role in producing the ML of SMSE. Furthermore, when the effect of trap centers on ML eliminated to the smallest, the sample with the easiest deformation structure possessed the highest ML intensity. The strong piezoelectric ability induced by the existence of defective phase is responsible for this phenomenon. These results indicate that the origin of ML is piezoelectricity-induced electroluminescence, that is, piezoelectricity impelled the trapped electrons to escape from the traps and produce ML.