Synthesis and characterization of Er super(3+ doped CaF) sub(2) nanoparticles

Er super(3+ doped CaF) sub(2) nanoparticles were synthesized by a chemical co-precipitation method. Effect of the dopant concentrations on the structure and optical properties of the CaF sub(2 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 Er) super(3)+ ions into CaF sub(2 resulted in the decrease in grain size and deterioration of crystallinity, but enlarged the lattice constants of CaF) sub(2). Additional annealing treatment at 400 degree C to the prepared CaF sub(2 removed the NO) sub(3) super(- and OH) super(-) 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.