Structural evolution and enhancement of luminescence in the Eu-doped oxyfluoride glass ceramics containing NaGdF4 nanocrystals

Abstract

Cubic-to-hexagonal phase evolution, narrow crystalline size distribution and enhancement of luminescence are simultaneously achieved by modifying the ratio of SiO2/B2O3 content in the Eu3+-doped oxyfluoride borosilicate glass ceramics containing NaGdF4 nanocrystals. The mechanisms of phase evolution of NaGdF4 nanocrystals are discussed on the basis of IR spectra, viscosity, XRD and TEM data. The results indicate that the stresses developed during the thermal treatment process play an important role in the phase evolution, which provides an experimental evidence of pressure-induced disorder-to-order phase evolution during the crystallization process for the first time. It is also found that the excitation and emission spectra as well as the luminescence lifetimes of the Eu3+ ions in the oxyfluoride glass ceramic are sensitive to the crystal lattice of NaGdF4.