Abstract
SrAl2O4 phosphor excited with fluorescent light or sunlight, has been recently reported to be a long-lasting afterglow (AG) phenomenon. However, the AG 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) measurements after UV or X-ray irradiation. A hole trap is presumed to be ascribed to Sr defects, which increases and is stabilized by a charge compensation behavior upon doping Dy ion. An electron trap probably originates from oxygen 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 with 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.
