Novel persistent phosphors of lanthanide–chromium co-doped yttrium aluminum gallium garnet: design concept with vacuum referred binding energy diagram

Abstract

We have developed Pr ³⁺–Cr ³⁺ and Tb ³⁺–Cr ³⁺ co-doped Y ₃Al ₂Ga ₃O ₁₂ (YAG G) persistent phosphors with orange (Pr ³⁺) and light green (Tb ³⁺) persistent luminescence.

Abstract

We have developed Pr ³⁺–Cr ³⁺ and Tb ³⁺–Cr ³⁺ co-doped Y ₃Al ₂Ga ₃O ₁₂ (YAG G) persistent phosphors with orange (Pr ³⁺) and light green (Tb ³⁺) persistent luminescence. The duration of their persistent luminance (of 0.32 mcd m ⁻²) can last up to about 8 h and 12 h, respectively. On the other hand, the persistent luminescence intensities of Nd ³⁺–Cr ³⁺ and Dy ³⁺–Cr ³⁺ co-doped YAG G samples are much weaker than those of the Pr ³⁺–Cr ³⁺ and Tb ³⁺–Cr ³⁺ co-doped ones, and the dominant persistent luminescence is mainly due to the deep-red transition of Cr ³⁺. The mechanisms of different persistent luminescence behaviors of these four samples can be explained by the vacuum referred binding energy (VRBE) diagram of lanthanide ions in the YAG G host. The stability of hole traps at the ground states of Pr ³⁺, Nd ³⁺, Tb ³⁺ and Dy ³⁺ ions and the possibility to collaborate with Cr ³⁺ electron traps to induce persistent luminescence are discussed in detail.