Intense Mechanoluminescence in Undoped LiGa₅O₈ with Persistent and Recoverable Behaviors

Abstract 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.