Synthesis and characterization of Er3+ doped CaF2 nanoparticles

Er3+ doped CaF2 nanoparticles were synthesized by a chemical co-precipitation method. Effect of the dopant concentrations on the structure and optical properties of the CaF2 nanoparticles was investigated. The X-ray powder diffraction and transmission electron microscopy analysis was used to characterize the structure and morphology of the nanoparticles. The nanoparticles with different dopant concentration exhibited a sphere-like morphology with diameters of about 8–36 nm. The incorporation of Er3+ ions into CaF2 resulted in the decrease in grain size and deterioration of crystallinity, but enlarged the lattice constants of CaF2. Additional annealing treatment at 400 °C to the prepared CaF2 removed the NO3− and OH− groups adsorbed on the particles’ surfaces, and improved the optical properties of the nanoparticles. The fluorescence intensity, with a maximum at approximately 0.4 mol%, decreased with the increase in doping concentration because of concentration quenching.

► Er3+:CaF2 nanoparticles were synthesized by co-precipitation method with particle size of 8–36 nm.
► Increasing dopant concentration increases lattice constants and decreases grain size.
► Annealing treatment has a remarkable effect on luminescence properties.
► Luminescence intensity decrease with the increasing of the dopant concentration.