Luminescence behavior of Er3+ ions in glass-ceramics containing CaF2 nanocrystals

The upconversion luminescence and near infrared luminescence of the Er3+ ions in transparent oxyfluoride glass-ceramics containing CaF2 nanocrystals have been investigated. The formation of CaF2 nanocrystals in the glass-ceramics was confirmed by XRD. The oscillator strengths for several transitions of the Er3+ ions in the glass and glass-ceramics have been obtained and then the Judd-Ofelt parameters were calculated. The split near infrared emission peaks of the Er3+ ions in the glass-ceramics can be observed because the Er3+ ions have been incorporated into crystalline environment of the CaF2 nanocrystals. The upconversion luminescence intensity of Er3+ ions in the glass-ceramics increased significantly with increasing heat treated time. The transition mechanism of the upconversion luminescence has been ascribed to a two-photon absorption process.