Role of dopant on long-lasting phosphor of strontium aluminate

SrAl2O4 phosphor excited with fluorescent light or sunlight, has been recen tly reported to be a long-lasting afterglow (AG) phenomenon. However, the A G mechanism has not been clarified yet, In this study, the long-lasting AG mechanism of SrAl2O4 phosphors doped with Eu and/or Dy, was investigated on the basis of AG, photoluminescence (PL), and thermoluminescence (TL) measu rements after UV or X-ray irradiation. A hole trap is presumed to be ascrib ed to Sr defects, which increases and is stabilized by a charge compensatio n behavior upon doping Dy ion. An electron trap probably originates from ox ygen defects, as produced by firing in a reductive atmosphere. Furthermore, the role of dopants (Eu, Dy ion) on SrAl2O4 phosphor co-doped with Eu and Dy ions, was studied by comparing the luminescence (AG and PL) phenomena wi th the distribution of dopant in SrAl2O4 matrix. Eu ion contributed closely to both the AG and PL behaviors, while the Dy ion contributes only to the AG phenomenon.