Time evolution of luminescence of Sr2SiO4:Eu2+

In this contribution, the photoluminescence, time-resolved luminescence and luminescence kinetics of alpha'-Sr2SiO4:Eu2+ are studied. The luminescence of Sr2SiO4:Eu2+ consists of two broad bands, peaked at 490 nm (blue-green) and 570 nm (yellow-orange), which originate from two luminescence centers, related to Eu2+ in ten-coordinated SI and nine-coordinated SII sites, respectively. Based on spectroscopic data the energetic structure of Sr2SiO4:Eu2+ has been developed, which includes the bands edges, energies of Eu2+ in the SI and SII sites and energies of strontium and oxygen vacancies. To investigate the long-lasting luminescence phenomenon in Sr2SiO4:Eu2+ the temperature influence on the time evolution of luminescence was analyzed. It has been found that the long-lasting luminescence is related to the Eu2+ in SII site. The shallowest traps responsible for emission decaying within a few seconds are tentatively attributed to the [Eu2+(SII)-V-O(center dot)] centers. The depth of traps responsible for the long-lasting luminescence observed at room temperature has been estimated as equal 0.73 eV.