Toward color variation of long persistent luminescence in Pr3+-doped garnet transparent ceramic phosphors

Abstract

Persistent luminescence (PersL) materials with diverse PersL colors hold great promise for glow-in-the-dark applications. However, extensive research has been devoted to merely altering the crystal field surrounding the activators and the opacity of usual power materials diminishes the PersL properties. Herein, Pr³⁺-doped (Ln)₃Al₂Ga₃O₁₂ (Ln = Lu, Y, and Gd) (LnAGG) transparent ceramics with various PersL properties are developed. Due to the variation in crystal field strength and distinct nonradiative relaxation processes from the 5d to 4f level in the three hosts, the intensity ratio of luminescence from the ³P_J and ¹D₂ levels of Pr³⁺ is distinct, and thus the PersL color can be changed from orange pink (Lu), red (Y) to greenish yellow (Gd). Additionally, the trap depth has the range within 0.64–1.21 eV for LuAGG:Pr³⁺, 1.15–1.54 eV for YAGG:Pr³⁺, and 0.62–1.16 eV for GAGG:Pr³⁺. The mechanism of PersL color variation is finally discussed with the aid of a vacuum referred binding energy diagram. These transparent phosphors with deep trap depth can be used as either cover layers for night-vision illumination or information storage applications, and this work may open a route for researchers to explore diverse PersL colors of lanthanide ion activated phosphors.