Intense Mechanoluminescence in Undoped LiGa 5 O 8 with Persistent and Recoverable Behaviors

The distinctive crystal characteristics of undoped LiGa5O8 allow the production of abundant defects and traps in the structure, contributing to attractive luminescent properties. In this work, the mechanoluminescent pathways of LiGa5O8 are demonstrated in terms of the defect induced localized energy levels and trap levels, which are further optimized by adjusting the synthesis atmosphere. The results suggest that the LiGa5O8 synthesized under a reducing atmosphere exhibits an extremely intense mechanoluminescence, which is even better than that of commercial ZnS:Cu. Because of the existence of shallow trap with the spontaneous transfer activity at room temperature, the mechanoluminescence of LiGa5O8 can also exhibit a persistent behavior, overcoming the transient emitting problem in most of the previous mechanoluminescent materials. In addition, the mechanoluminescence of LiGa5O8 can be easily and quickly recovered by refilling the energy in traps. As a result, the undoped LiGa5O8 is confirmed to be an efficient material with intense, persistent, and recoverable mechanoluminescence, which is promising to substitute the doped ones for various applications.