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

Abstract

We have developed Pr3+-Cr3+ and Tb3+-Cr3+ co-doped Y3Al2Ga3O12 (YAGG) persistent phosphors with orange (Pr3+) and light green (Tb3+) 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 Nd3+-Cr3+ and Dy3+-Cr3+ co-doped YAGG samples are much weaker than those of the Pr3+-Cr3+ and Tb3+-Cr3+ co-doped ones, and the dominant persistent luminescence is mainly due to the deep-red transition of Cr3+. 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 YAGG host. The stability of hole traps at the ground states of Pr3+, Nd3+, Tb3+ and Dy3+ ions and the possibility to collaborate with Cr3+ electron traps to induce persistent luminescence are discussed in detail.