Synthesis of SrAl2O4:Eu2+ phosphors co-doped with Dy3+, Tb3+, Si4+ and optimization of co-doping amount by response surface method

Abstract Dy 3+ doped SrAl 2 O 4 :Eu 2+ phosphors were synthesized by high temperature solid phase method in a weak reducing atmosphere (5% H 2 + 95% N 2 ). The relationship between the crushed granularity and the phosphors brightness was studied. The effect of co-doping amount of Dy 3+ , Tb 3+ and Si 4+ on the structure and properties of SrAl 2 O 4 :Eu 2+ via response surface method was investigated. Photoluminescence measurement results showed that the initial afterglow brightness of 0.002 mol% Dy 3+ doped SrAl 2 O 4 :Eu 2+ 0.002 phosphors decreased after first increased within the sintering temperature range from 1150 to 1400 °C, which created the highest value of 12,101 mcd/m 2 at 1300 °C. Numerous coarse particles in the powder ought to be crushed for the practical application, however, the brightness became lower accompanied by the decrease of the granularity. The luminescence property of SrAl 2 O 4 :Eu 2+ sintered at 1200 °C improved by co-doping Dy 3 + –Tb 3 + –Si 4+ . The results of response surface method showed that the influence extent on the luminescence property was Dy 3+ > Tb 3+ > Si 4+ . When the co-doping amount in SrAl 2 O 4 :Eu 2+ 0.002 phosphors of Dy 3+ , Tb 3+ and Si 4+ was 0.001 mol%, 0.0005 mol% and 0.002 mol%, respectively, the initial afterglow brightness of SrAl 2 O 4 was up to the highest value of 12,231 mcd/m 2 , which was in good agreement on the predicted maximum value of 12,519 mcd/m 2 with the optimum co-doping amount of 0.0015 mol% Dy 3+ , 0.0005 mol% Tb 3+ and 0.0017 mol% Si 4+ . The brightness of co-doped phosphors not only increased by 56.79% than that of SrAl 2 O 4 :Eu 2+ 0.002 , Dy 3+ 0.002 sintered at 1200 °C, but also was above that of 1300 °C. The emission spectra results showed that, compared with 0.001 mol% Dy 3+ doped phosphor, the emission peak of 0.001 mol% Dy 3 + –0.001 mol% Tb 3+ co-doped phosphor generated red shift and increased by 9.3% in emission intensity; 0.001 mol% Dy 3 + –0.004 mol% Si 4+ and 0.001 mol% Dy 3 + –0.001 mol% Tb 3 + –0.004 mol% Si 4+ co-doped SrAl 2 O 4 :Eu 2+ 0.002 emission peak created blue shift and increased by 37.2% and 47.6% in emission intensity, respectively.