Mechanoluminescence of Persistent Luminescent SrAl$lt;inf$gt;2$lt;/inf$gt;O$lt;inf$gt;4$lt;/inf$gt;: (Eu$lt;sup$gt;2+$lt;/sup$gt;, Dy$lt;sup$gt;3+$lt;/sup$gt;) Material Prepared by Electron Beam Reduction

Long persistent luminescent SrAl2O4: (Eu, Dy) was prepared by electron beam reduction. The asprepared material was mechanically ball-milled into fine powder, and the powder was mixed with wear resistant epoxy resin. Then, the epoxy resin mixed persistent luminescent was coated on quartz glass plate by screen printing with thickness of about 1000 nm. The mechanoluminescent properties of the as-persistent luminescence film was characterized by falling ball impact technique with a homemade device for measuring mechanoluminescence intensity based on a single avalanche diode and a pico-amper meter. It is found that electron beam reduced SrAl2O4: (Eu, Dy) shows strong mechanoluminescence with high signal/background ratio of 1.25 and high signal/noise ratio. Further study found that intensity of the mechanoluminescence produced was proportional to exponential of the initial height of the ball (i.e., the final kinetic energy of the ball before impact) before falling down, and a decay curve was similar to that of persistent photoluminescence. These results indicate that mechanoluminescence is caused by impact energy of the ball which promotes electrons into traps, and then release via normal long persistent luminescent.