Enhancement of ultraviolet upconversion photoluminescence of Y7O6F9:Pr, Gd induced by Li+ codoping☆

Ultraviolet upconversion photoluminescence materials have great potential in various fields, but the improvement of the upconversion efficiency is challenging. Codoping of Li+ is considered as an effective strategy and widely used to improve the photoluminescence properties of phosphors. In this paper, Li+ is introduced into a Y7O6F9:Pr3+,Gd3+ system. The effect of Li + codoping on the phase purity, crystal structure, microstructure, downshifting and upconversion photoluminescence as well as the decay dynamic of the phosphors was studied. It is revealed that the overall photoluminescence efficiency and the energy transfer efficiency from Pr3+ to Gd3+ are greatly promoted. The downshifting and upconversion photoluminescence increase by 2.58 and 10 times as 6 mol% of Li+ is codoped. The photoluminescence decay dynamic study shows that the 3P0 state decays slower in the Li + -containing phosphor than the Li+-free one. The improvement of the photoluminescence properties is due to the increase of the crystallinity and the reduce of the quenching center.