Microstructure and photoluminescence of Eu-doped Sr3Al2O6 phosphors calcined with and without H3BO3 flux

The development of highly efficient and stable red phosphors fabricated using cost-effective and simple mass-production methods is essential for applications in future displays and lighting devices. Herein, we investigate the phase formation, microstructures, and luminescence properties of Sr 3 Al 2 O 6 :Eu powders synthesized using a solid-state reaction process. Single-phase Sr 3 Al 2 O 6 :Eu phosphors exhibiting excellent photoluminescence with color-tunable orange-red and red colors under different excitation wavelengths were successfully synthesized. The optimal Eu doping concentration of Sr 3 Al 2 O 6 , yielding strong photoluminescence with phase stability, was 5 at. %, with the concentration quenching point determined by systematic exploration. The addition of H 3 BO 3 as a flux significantly affected the grain size and improved the emission intensity of the synthesized (Sr 0.95 Eu 0.05 ) 3 Al 2 O 6 phosphors up to 12.5 wt %, while secondary phases were formed at higher flux concentrations. The photoluminescence intensities of the 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transitions of 12.5 wt % H 3 BO 3 added (Sr 0.95 Eu 0.05 ) 3 Al 2 O 6 increased by 3.4 and 4.2 times compared with the flux-free powders under the 394 nm-wavelength excitation, while the decay time decreased from 7.35 to 5.40 ms. Our report of the enhanced photoluminescence intensity and shortened decay time of (Sr 0.95 Eu 0.05 ) 3 Al 2 O 6 phosphors following the flux addition is promising for production of single-phase phosphors emitting multi-colors, which is needed for optical devices activated by various excitation frequencies.