Luminescent properties of stabled hexagonal phase Sr1−xBaxAl2O4:Eu2+ (x=0.37–0.70)

Stabled hexagonal phase Sr1−xBaxAl2O4:Eu2+ (x=0.37–0.70) was prepared by solid-state method. Result revealed that the structure behavior of the SrAl2O4:Eu2+ calcined at 1350 °C in a reducing atmosphere for 5 h strongly depended on the Ba2+ concentration. With increasing Ba2+ concentration, a characteristic hexagonal phase can be observed. When 37–70% of the strontium is replaced by barium, the structure of the prepared sample is pure hexagonal. Photoluminescence and excitation spectra of the samples with different x and doped with 2% Eu2+ were investigated. Changes in the emission spectra were observed in the two different phases. The green emission at 505 nm from Eu2+ was found to be quite strong in the hexagonal phase. The intensity and peak position of the green luminescence from Eu2+ changed with increasing content of Ba2+. The strongest green emission was obtained from Sr0.61Ba0.37Al2O4:Eu2+. The decay characteristics of Sr1−xBaxAl2O4:Eu2+ (x=0.37–0.70) showed that the life times also varied with the value of x. Furthermore, the emission colors and decay times varying with x could be ascribed to the variation of crystal lattice.