Manipulating alkali charge compensation to improve red fluorescence and thermostability in Ba5P6O20:Eu3+ phosphor

Phosphate Ba5P6O20 (BPO) with short absorption edge is a promising phosphor host material. However, the nonequivalent replacement of trivalent rare earth activators for bivalent barium generally induces the defects, which is unfavorable for efficient fluorescence. Meanwhile, the diverse Ba2+ coordination fields bring the challenge for determining the occupancy sites of activator ions. In this study, the alkali charge compensators A+ (A = Li, Na, and K) are co-doped into BPO:Eu3+ to enhance significantly red-emitting properties. Through employing the theoretical and spectral methods, the multiple Eu3+ occupancy sites are revealed in detail. The luminescent intensity is improved by 120 %, 149 %, and 164 %-fold for Li+, Na+ and K+ co-doping, separately. The luminescent efficiency and thermal stability are also remarkably enhanced. Additionally, the indoor and plant lighting applications for the resulting phosphor are investigated, displaying satisfactory performance. The study manifests that the title material compensated with alkali metal ions A+ is expected to become a red-emitting candidate for multifunctional lighting utilizations.