Understanding the mechanoluminescent mechanisms of manganese doped zinc sulfide based on load effects

In this work, manganese doped zinc sulfide (ZnS: Mn2+) powder was synthesized, which was further composited with epoxy resin. In addition to the bright photoluminescence (PL), two types of mechanoluminescence (ML), i.e., friction and compression induced luminescence, were observed in ZnS: Mn2+/epoxy composites. To deeply understand the mechanoluminescent mechanisms of ZnS: Mnn(2+), the performance differences between PL and ML were investigated. The results suggested that the piezoelectric effect induced electroluminescence should not be the exact mechanism of ML. Moreover, load effects on the friction and compression induced ML as well as the thermoluminescence (ThL) were investigated. The variations of trap depth and carrier density in ZnS: Mnn(2+) before and after mechanics stimulation provided direct evidence that the release of electrons from traps should be responsible for ML. The load effects of ML also supported the proposed trap-based mechanisms, and the underlying theory was discussed in detail. This work first presents solid evidences for the trap-based mechanoluminescent mechanisms of ZnS: Mnn(2+) in elastic region.