Preparation and upconversion luminescent properties of Yb³⁺/Er³⁺ doped transparent glass-ceramics containing CaF₂ nanocrystals

Yb³⁺/Er³⁺ doped high-fluoride glass-ceramics were prepared by the high-temperature melting method. The crystal morphology and structure of the rare-earth doped glass-ceramics were characterized by X-ray diffraction, infrared spectra, and high-resolution transmission electron microscope. The influence of crystal size and distribution on the transmittance of glass-ceramics was analyzed. The upconversion emission intensity of the rare earth doped glass-ceramics at different heat treatment temperatures was evaluated. It is shown that the precipitation of CaF₂ crystals greatly improves the upconversion emission efficiency of rare earth ions. By analyzing different high-power pump lasers and corresponding up-conversion luminous intensities, the mechanism of up-conversion luminescence of this material is further elaborated.