Luminescence investigation of Yb3+/Er3+ codoped single LiYF4 microparticle

Tetragonal phase LiYF4:Yb3+/Er3+ microparticles are synthesized via facile hydrothermal method. Single LiYF4 microparticle is excited with IR laser at 980 nm in a confocal setup, and strong green and weak red emissions are observed. It is found that single LiYF4:Yb3+/Er3+ microparticle with sub-structure presents stronger upconversion luminescence emission and smaller intensity ratio of red to green emission than that from LiYF4:Yb3+/Er3+ microparticle with no sub-structure. The possible mechanism, the influence of particle size and the existence of EDTA on the upconversion luminescence emission are investigated. The current study suggests that the luminescence observation with single micropaticle can effectively avoid the influence of environment and neighbor particles, which is important for investigating the luminescence properties of micro- or nano-crystals and for extending their application.