Enhanced Mechanoluminescence of ZnS: Mn at 77K

Manganese-doped zinc sulfide (ZnS: Mn) is one of the brightest mechanoluminescing (ML) materials. While its mechanoluminescing properties at room-temperature have been widely studied, its behavior at cryogenic temperatures remains underexplored. Here, we report on the first set of measurements performed at 77K for two different impact energies: low (indirect) and high (direct), created in a composite form. In this investigation, 4 parameters were studied as a function of temperature and impact energy. These include emission intensity, emission wavelength, rise time, and decay time. Results show up to a fivefold increase in emission intensity at 77K compared to room temperature and a noticeable red shift in the emission band for all cases. Under direct impact the fast and slow decay times reduced from 129.6 ± 4 µs to 55.5 ± 5.7 µs and from 890.6 ± 150.1 µs to 290.9 ± 25.4 µs, respectively while in the indirect case the fast decay increased from 38.3 ± 1.7 µs to 82.2 ± 16.1 µs, and the slow decay increased from 318.3 ± 12.8 µs to 357.8 ± 40.6 µs. The rise time also showed some temperature dependence and efforts are undergoing to isolate the behavior of ZnS:Mn from the encapsulating polymer.