Synthesis of the nano-sized SrAl₂O₄ phosphors by wet processing and its photoluminescence properties

Eu²⁺ and Dy³⁺ co-doped strontium aluminate, SrAl ₂O₄ long phosphorescent phoshor was fabricated and its photoluminescence was characterized. The phosphor, SrAl₂O₄ :Eu²⁺,Dy³⁺ was synthesized by a coprecipitation in which metal salts of Sr(NO₃)₂, Al(NO₃) ₃·9H₂O, were dissolved in (NH₄) ₂CO₃ solution with adding Eu(NO₃) ₃·5H₂O and Dy(NO₃)₃· 5H₂O as a activator and coactivator, respectively. The coprecipitated products were separated from solution, washed, and dried in a vacuum dry oven. The dried powders were then mixed with 3 wt% B₂O₃ as a flux and heated at 800- 1400°C for 3 h under the reducing ambient atmosphere of 95%Ar+ 5%H2 gases. For the synthesized SrAl₂O₄ : Eu²⁺ ,Dy³⁺ ,properties of photoluminescence such as emission, excitation and decay time were examined. The emission intensity increased as the annealing temperature increased and showed a maximum peak intensity at 510 nm with a broad band from 400-650 nm. Monitored at 520 nm, the excitation spectrum showed a maximum peak intensity at 315-320 nm wavelength with a broad band from 200-500 nm wavelength. The decay time of SrAl ₂O₄:Eu²⁺,Dy³⁺ increased as the annealing temperature increased.