Characterization of Y 2O 2S:Eu 3+, Mg 2+, Ti 4+ Long-Lasting Phosphor Synthesized by Flux Method

Abstract

Long-lasting phosphor Y 2O 2S: Eu 3+, Mg 2+, Ti 4+ was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu 2O 3 content in Y 2O 2S: Eu x 3+ (0.01 ≤ x ≤ 0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y 2O 2S: Eu 3+ crystal structure, Eu 3+ ions only replaced Y 3+ ions' places in which it posited center position of c axis. With the increase of Eu 2O 3 content, the position of the strongest emission peak changed from 540 nm ( 5D 1→ 7F 2 transition) to 626 nm ( 5D 0→ 7F 2 transition), and the maximum intensity was obtained when x = 0.09 in Y 2O 2S: Eu x 3+ (0.01 ≤ x ≤ 0.10). This is due to the environment of trivalent europium in the crystal structure of Y 2O 2S. Doping with Mg 2+ or Ti 4+ ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg 2+ and Ti 4+ ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd · m −2). Thus the LLP mechanism was analyzed.