Er 3+ doped transparent oxyfluoride glass ceramics containing LaF3 nanocrystals were prepared and the up-con- version and near infrared luminescence behavior of Er 3+ in glasses and glass ceramics were investigated. With increasing heat-treating time and temperature, the size （varied from 0 to 19 nm） and crystallinity （varied from 0 to 47%） of LaF3 nanocrystals in the glass ceramics are increased. The up-conversion luminescence intensity of Er 3+ ions in the glass ceramics is much stronger than that in the glasses and increased significantly with increasing heat-treating time and temperature. The near infrared emission of Er 3+ ions in the glass ceramics is found to be similar to that in the glasses.
