Identifying a Cyan Ultralong Persistent Phosphorescence (Ba, Li) (Si, Ge, P)2O5:Eu2+, Pr3+ via Solid Solution Strategy

A series of cyan emission (Ba, Li) (Si, Ge, P)(2)O-5:Eu2+, Pr3+ long persistent phosphors (LPP) were designed by solid solution strategy and synthesized by solid-state reaction; the crystal structure and photoluminescence of this long persistent phosphor have been analyzed systematically. Under 256 nm light excitation, the as-prepared (Ba, Li) (Si, Ge, P)(2)O-5:Eu2+, Pr3+ presents a strong cyan emission located at 514 nm, and the decay time of samples can be extended to about 38 h (BaSi2O5:0.008Eu(2+), 0.01Pr(3+)), 47 h (BaSi1.5Ge0.5Os:0.008Eu(2+), 0.01Pr(3+)), and 56 h (Ba0.92Li0.08Si1.92P0.08O5:0.008Eu(2+), 0.01Pr(3+)) after ceasing the excitation source. A number of excitation duration (1 s <= t <= 30 s)-, decay duration (10 min <= t <= 10 h)-, and temperature-dependent thermoluminescence experiments of (Ba, Li) (Si, Ge, P)(2)O-5:0.008Eu(2+), 0.01Pr(3+) were conducted, revealing that the existence of shallow and deep traps caused by Eu2+ and Pr3+ ions in samples gives rise to the excellent LPP property. According to the experimental results, a feasible mechanism of persistent luminescence of (Ba, Li) (Si, Ge, P)(2)O-5:0.008Eu(2+), 0.01Pr(3+) was proposed and illustrated in detail.