Luminescence Properties of Blue-green Phosphors Sr_1-xBa_xAl₂O₄∶Eu²⁺for White LED

Abstract

Sr1-xBaxAl2O4∶Eu2+ phosphors were synthesized in a reducing atmosphere by high temperature solid state method at 1 350 ℃.The patterns of XRD indicated that the crystal structure of the phosphors are the monoclinic phase of SrAl2O4 when x0.4 and the simple hexagonal phase of BaAl2O4 when x≥0.4 because of crystal lattice expands with Ba2+ ion substitution for Sr2+ ion.Photoluminescence experiments were carried out to study the luminescence properties of the phosphors excited under 360 nm.The results showed that emission spectra gradually changed from single green emission(λmax=516 nm) to blue-green dual-emission(λmax1= 441 nm,λmax2=486 nm) with the increase of x. When x was 0.5,there was a better property in Sr0.5Ba0.5Al2O4∶Eu2+.From the relationship between the concentration of Eu2+ ion and the intensities of emissions in Sr0.5Ba0.5Al2O4∶y%Eu2+,we get that the maximum dual-emission intensity when y=0.29%.There exist a concentration quenching effect in Sr0.5Ba0.5Al2O4∶Eu2+, and the study points out that the mechanism of concentration quenching effect is electric dipole-dipole interaction.