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

Abstract

Dy3+ doped SrAl2O4:Eu2+ phosphors were synthesized by high temperature solid phase method in a weak reducing atmosphere (5% H2+95% N2). The relationship between the crushed granularity and the phosphors brightness was studied. The effect of co-doping amount of Dy3+, Tb3+ and Si4+ on the structure and properties of SrAl2O4:Eu2+ via response surface method was investigated. Photoluminescence measurement results showed that the initial afterglow brightness of 0.002mol% Dy3+ doped SrAl2O4:Eu2+0.002 phosphors decreased after first increased within the sintering temperature range from 1150 to 1400°C, which created the highest value of 12,101mcd/m2 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 SrAl2O4:Eu2+ sintered at 1200°C improved by co-doping Dy3+–Tb3+–Si4+. The results of response surface method showed that the influence extent on the luminescence property was Dy3+>Tb3+>Si4+. When the co-doping amount in SrAl2O4:Eu2+0.002 phosphors of Dy3+, Tb3+ and Si4+ was 0.001mol%, 0.0005mol% and 0.002mol%, respectively, the initial afterglow brightness of SrAl2O4 was up to the highest value of 12,231mcd/m2, which was in good agreement on the predicted maximum value of 12,519mcd/m2 with the optimum co-doping amount of 0.0015mol% Dy3+, 0.0005mol%Tb3+ and 0.0017mol% Si4+. The brightness of co-doped phosphors not only increased by 56.79% than that of SrAl2O4:Eu2+0.002, Dy3+0.002 sintered at 1200°C, but also was above that of 1300°C. The emission spectra results showed that, compared with 0.001mol% Dy3+ doped phosphor, the emission peak of 0.001mol% Dy3+–0.001mol%Tb3+ co-doped phosphor generated red shift and increased by 9.3% in emission intensity; 0.001mol% Dy3+–0.004mol% Si4+ and 0.001mol% Dy3+–0.001mol%Tb3+–0.004mol% Si4+ co-doped SrAl2O4:Eu2+0.002 emission peak created blue shift and increased by 37.2% and 47.6% in emission intensity, respectively.