Effect of Oxygen Vacancies on the Persistent Luminescence of Y<sub>3</sub>Al<sub>2</sub>Ga<sub>3</sub>O<sub>12</sub>:Ce<sup>3+</sup>,Yb<sup>3+</sup> Phosphors
Ting Yang, Hongyi Jiang, Ou Hai, Ye Dong, Shuning Liu, Shuai Gao
Abstract
The effect of oxygen vacancies (VO) and the atmosphere influence on persistent luminescence (PersL) in Y3Al2Ga3O12 (YAGG):Ce3+,Yb3+ are investigated by heating it in CO2, air, and 10% H2/90% Ar atmospheres. The VO-rich YAGG phosphors with outstanding PersL are successfully obtained by the common contribution of the reducing atmosphere and the incorporated Yb3+ ions, and the concentration of oxygen vacancies in the phosphors is characterized by X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. Compared to the best sample prepared in neutral CO2, the reduced sample shows an increase of 30% in initial intensity and 100% in duration time, while the oxidized sample decreases drastically and shows a faint and undetectable PersL. The enhancement is mainly caused by the abundant formation of VO, which is achieved by the pairing of VO with Yb2+ ions. The newly created VO by the reducing calcination is inferred to be adjacent to the Yb site and forms a compensation-type defect cluster due to the charge compensation effect. These findings reveal that understanding the effect and formation of VO is of great significance to design a high-performance phosphor.