Search

Transparent oxyfluoride glass ceramics containing LaF3 and ErF3 were prepared and the fluorescent characteristics of Er3+, such as emission spectra and lifetime of excited states were investigated. By heat-treatment of the as-prepared glass above the glass transition temperature, the formation of LaF3 nanocrystals was confirmed by X-ray diffraction (XRD). With increasing annealing temperature and time, the fluorescence intensity at 540 nm and around 1000 nm increased and the lifetime of the 4S3/2 level became longer. Also the 540 nm upconversion intensity by 970 nm pumping increased drastically. These results could be attributed to the change of ligand field of Er3+ ions and the decrease of effective phonon energy because of the precipitation of LaF3 nanocrystals and the incorporation of some of Er3+ ions into fluoride. [Copyright &y& Elsevier]