Correlation of triboluminescence and contact stresses in ZnS:Mn/polymeric matrix composite

A relationship between sliding-induced light emission of ZnS:Mn dispersed in polymer matrix and sliding stress determined by using contact mechanics is investigated. In addition to normal loads, the magnitude of exerting stress is also controlled by frictional force and mechanical properties of the composite so that its linear proportion to the applied force is an imprudent assumption. Emission spectra suggest that manganese-associated energy levels are not influenced by deformation. Not only is the emission probability increased but also the stiffness of the composite is enhanced by higher volume fraction of the phosphors. In accordance with contact mechanics, the quantitative results show that a total emission intensity increases non-linearly with contacting stress. Based on the observations, an empirical relationship might be expressed in the form of an exponential function of a square of the exerting stress.