Mechanoluminescence of ZnS:Mn phosphors and its correlation to impact energy and contact geometry.

The influence of the impulsive mechanical energy and the contact geometrical parameters on stress-induced light emission of ZnS-based phosphors dispersed in polymeric matrix is investigated using modified impact test equipment. At a low to moderate energy region, luminescent pulses consist of two distinguishable peaks that can be assigned to a loading and unloading sequence, respectively. Transient characteristics are found to be independent of the external excitation. An increment of peak emission intensity with higher impact energy and smaller tip diameter indicates a significant relationship of mechanoluminescence to the geometry of contact. Intense emission deviating from the linearity and an absence of the secondary peak are suggested to be the consequence of fractoluminescence.