Lifetime-based measurement of stress during cyclic elastic deformation using mechanoluminescence of SrAl₂O₄:Eu²⁺.

The present study focused on the rise time and decay times of mechanoluminescence (ML) during cyclic elastic deformation of SrAl₂O₄:Eu²⁺. The time constants during compression and decompression, τup and τdown, respectively, did not change from the 2nd to the 5th cycle. Both τup and τdown were expressed by a linear function of the maximum load and the inverse of the loading rate. τup depended only on the loading time, whereas τdown was affected by the loading time and the rate of change of the strain energy. Measuring τdown may enable evaluation of the loading conditions even under cyclic loading and may enhance the practicality of a ML phosphor.