Long afterglow in hexagonal SrAl2O4:Eu2+, Dy3+ synthesized by crystallization of glass and solidification of supercooled melts

High temperature phase of hexagonal SrAl2O4:Eu2+,Dy3+ crystals were synthesized via two paths; (1) heat-treatment on glass (a conventional glass crystallization technique), and (2) solidification of supercooled melts in melt-cooling process with non-contact process, where a levitation melting technique was used to obtain precursor glass and ceramics beads. Hexagonal SrAl2O4 (βʹ-phase) were formed in both samples, not stable phase of monoclinic phase (α-phase), which is well known as one of the best afterglow material. Both samples with hexagonal phase showed brighter broad green emission, higher intensity of PLE peak in visible region (λ=400-500 nm), and longer duration of afterglow compared to monoclinic SrAl2O4:Eu2+,Dy3+ sintered by solid-state reaction.