Effect of lithium halide on glass network structure and upconversion luminescence in Er³⁺ co-doped oxyfluoride glass ceramics containing NaGdF₄ nanocrystals

LiR(R = Br, Cl, F) co-doped oxyfluoride glass ceramics containing NaGdF₄ nanocrystals were prepared. The effect on glass network structure by dopants was investigated through the Raman spectra. The crystallization temperature and integrity of the glass network structure was gradually reduced by introducing halogen ions. The types and distribution of nanocrystals were determined by X-ray diffraction and transmission electron microscope. The size of nanocrystals were shown in column type distribution map. The mean size of nanocrystals was bigger from SABr to SAF. The upconversion luminescence of Er³⁺ in SABr, SACl and SAF were study. The intensity ratio of red and green light was reduced in glass ceramics when the content from LiBr turn to LiF.