Influence of Yb Concentration on the Optical Properties of CaF2 Transparent Ceramics Codoped with Er and Yb

Er, Yb:CaF2 nanoparticles with different Yb concentrations were synthesized by a coprecipitation method using nitrates as raw materials. X-ray powder diffraction and transmission electron microscopy analysis showed that the nanoparticles were single fluorite phase and the nanoparticle size was found to decrease with increasing Yb concentrations. The obtained nanoparticles were hot-pressed at 800 degrees C under 30 MPa under vacuum environment to fabricate Er, Yb:CaF2 transparent ceramics. The influence of Yb ion concentrations on the optical transmission, microstructure, and luminescence properties of Er, Yb:CaF2 transparent ceramics were investigated. The addition of Yb ions was found effectively to reduce grain size and has a positive effect on improving the optical transmission of Er, Yb:CaF2 transparent ceramics. The highest transmittance in the near-infrared spectral region of the Er, Yb:CaF2 transparent ceramic reached about 90%. The green, red, and near-infrared emission intensities were found to increase with increasing Yb concentration.