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

Feng, Peng, Li, Gen, Guo, Haijie, Liu, Dongwei, Ye, Qiangfei, Wang, Yuhua
Journal of physical chemistry 2019 v.123 no.5 pp. 3102-3109
barium, crystal structure, europium, germanium, ions, phosphorescence, photoluminescence, silicon, thermoluminescence
A series of cyan emission (Ba, Li) (Si, Ge, P)₂O₅: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)₂O₅:Eu²⁺, Pr³⁺ presents a strong cyan emission located at 514 nm, and the decay time of samples can be extended to about 38 h (BaSi₂O₅:0.008Eu²⁺, 0.01Pr³⁺), 47 h (BaSi₁.₅Ge₀.₅O₅:0.008Eu²⁺, 0.01Pr³⁺), and 56 h (Ba₀.₉₂Li₀.₀₈ Si₁.₉₂ P₀.₀₈O₅:0.008Eu²⁺, 0.01Pr³⁺) 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)₂O₅:0.008Eu²⁺, 0.01Pr³⁺ 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)₂O₅:0.008Eu²⁺, 0.01Pr³⁺ was proposed and illustrated in detail.