Preparation And Optical Properties Of Rare Earth-doped Oxyfluoride Glass Ceramics

In this paper, UV-excited luminescence spectra, upconversion luminescence spectra, Near-infrared luminescence spectra, UV-Vis absorption spectra were used to study the preparation process and luminescence behavior of Er³⁺ ions doped or Er³⁺ and Yb³⁺ co-doped oxyfluoride glass ceramics.Er³⁺ doped oxyfluoride glass ceramics containing LaF₃ nanocrystals were prepared. With increasing heat treatment time and temperature, the size and crystallinity of LaF₃ nanocrystals in the glass ceramics increased. The upconversion luminescence intensity of Er³⁺ ions in the glass ceramics was much stronger than that in the glasses and increased significantly with increasing heat treatment time and temperature. The near infrared emission of Er³⁺ ions in the glass ceramics was found to be similar to that in the glasses. The upconversion luminescence intensity of Er³⁺ in Er³⁺ and Yb³⁺ co-doped glasses and glass ceramics increased significantly due to energy transfer between Er³⁺ and Yb³⁺. Major spectroscopic parameters, spontaneous emission probabilities, branching ratio and radiative lifetimes, of Er³⁺ in oxyfluoride glasses and glass ceramics were obtained. The values of J-O parameters of oxyfluoride glasses and glass ceramics located between fluoride glasses and oxide glasses. The effect of ratio of Er³⁺/Yb³⁺ on luminescence behavior of Er³⁺ and Yb³⁺ co-doped glasses and glass ceramics has been investigated. With increase of Yb³⁺, upconversion luminescence intensity increased gradually due to efficient energy transfer from Yb³⁺ to Er + and large absorption section of Yb³⁺ around 980nm.Novel oxyfluoride glass ceramics containing Ba₂LaF₇ nanocrystals were prepared using BaF₂ and La₂O₃ as raw materials. The glass ceramics containing different kinds of nanocrystals such as Ba₂LaF₇, LaF₃, La₂O₃ can be obtained. Upconversion luminescence intensity of glass ceramics containing fluoride crystals was stronger than that of glass ceramics containing oxide crystals. A novel serial of oxyfluoride glass ceramics containing Sr₂YF₇, Sr₂LaF₇, Sr₂GdF₇ nanocrystals were prepared and relationship between upconversion luminescence intensity and heat treatment temperature was investigated.