Luminescence properties of Ho3+ co-doped SrAl2O4:Eu2+, Dy3+ long-persistent phosphors synthesized with a solid-state method

• Published in: Journal of molecular structure 2013-07, Vol.1044, p.87-93
• Main Authors: Győri, Z., Havasi, V., Madarász, D., Tátrai, D., Brigancz, T., Szabó, G., Kónya, Z., Kukovecz, Á.
• Format: Article
• Language: English
• Subjects: Aluminum; Decay rate; Economics; Holmium; ions; Luminescence; Optical properties; Optimization; Phosphor; Phosphors; Solid-state method; SrAl2O4; Strontium
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2012.11.008

In this study our aim was partially substituting or replacing Dy3+ co-dopant ions in SrAl2O4:Eu2+, Dy3+ phosphors with less expensive Ho3+ co-dopant ions in order to open a more economical way towards the industrial scale synthesis of long-persistent strontium-aluminate phosphors while maintaining the good optical properties of Dy3+ co-doped phosphors. This was achieved by finding the optimum ratio between the Dy3+ and Ho3+ co-dopants to get the highest initial intensity and by compensating the fast decay speed caused by Ho3+ co-doping via defect site generation in the host through non-stochiometric Sr/Al ratios. The initial emission intensity was the highest when the co-activator was substituted entirely with Ho3+ ions, and even the phosphors containing mixed co-activators featured higher initial emission intensities than the reference Dy3+ co-doped samples. However, the samples co-activated with Ho3+ or mixed co-activators exhibited faster decay speeds relative to the Dy3+ co-activated samples. This negative effect could be compensated by increasing the relative amount of aluminum in the phosphor.