Photoluminescence Features and Mechanoluminescence Mechanism Inherent in Composite Materials Based on a Photopolymerizing Resin and Finely Dispersed Powders of SrAl2O4:(Eu2+,Dy3+) and Sr4Al14O25:(Eu2+,Dy3+,B) luminophores

Abstract

Photoluminescence spectra and kinetics have been studied for finely dispersed powders of such luminophores as SrAl₂O₄:(Eu²⁺,Dy³⁺) and Sr₄Al₁₄O₂₅:(Eu²⁺,Dy³⁺,B). Several lasers with different wavelengths (λ = 355, 404, 440 and 530 nm) were used for the excitation of photoluminescence. The photoluminescence of the materials is revealed to occur in a long-wave spectral range from 550 to 750 μm, which indicates the presence of energy levels, the radiative transitions between which form the radiation spectrum. The structure of the powders has been studied using a scanning electron microscope. It is established that the powder consists of microparticles (granules) up to 100 μm in size with a grain size up to 25 μm. According to the results of studies on the mechanoluminescence of SrAl₂O₄:(Eu²⁺,Dy³⁺) and Sr₄Al₁₄O₂₅:(Eu²⁺,Dy³⁺,B) powders, it is concluded that the mechanoluminescence is excited via an activation of traps when they interact with the electric fields of moving grain-boundary dislocations in the course of intergranular slipping during the deformation of microparticles under an impact load.