Effect of host compositions on the afterglow properties of phosphorescent strontium aluminate phosphors derived from the sol-gel method

The effect of compositions of host precursors on the afterglow and phosphorescent decay properties of Eu²⁺- and Dy³⁺-coactivated strontium aluminates (SAED) synthesized by a sol-gel process has been investigated. A variety of strontium aluminates such as Sr₃Al₂O₆, SrAl₂O₄, and SrAl₁₂O₁₉ have been identified in the samples prepared from starting precursors with Al/Sr ratios ranging from 1 to 12, respectively. The initial afterglow intensity (I₀) for SAED phases was found to vary with Al/Sr ratio of the sol-gel precursor, with a maximal I₀ appearing in the sample with Al/Sr of 2 in which SrAl₂O₄ dominated. The afterglow decay rate was found to be fastest for sample with Al/Sr ratio of 1:1 in which Sr₃Al₂O₆ phase dominated. Moreover, the afterglow decay rates for those with Al/Sr ratio of 2:1 to 12:1, in which SrAl₂O₄ and SrAl₁₂O₁₉ dominated, were found to be slow and similar.