Red persistent luminescent silicate nanoparticles

Red persistent luminescent diopside nanoparticles doped with Mn²⁺ and codoped with RE³⁺ (Eu²⁺, Dy³⁺) have been obtained by sol-gel method. The influence of codoping rare earth ions on the persistent luminescence was studied by wavelength-resolved thermally stimulated luminescence (TSL) measurements from 30 to 650 K after X-ray irradiation. From these first results, a mechanism of persistent luminescence is proposed. In this mechanism Mn²⁺ and Eu²⁺ act as TSL recombination centers, Mn³⁺ and Eu³⁺ being stable hole centers, whereas Dy³⁺ acts as a good electron trap giving rise to a TSL peak at high temperature. Finally, persistent luminescence was measured. Intensity and persistence of the red luminescence of CaMgSi₂O₆: Mn²⁺–Dy³⁺ are better than those of CaMgSi₂O₆: Mn²⁺ and CaMgSi₂O₆: Mn²⁺–Eu²⁺, which are in agreement with the results of TSL.