Controlled Synthesis of Eu3+ doped La2O2S nanophosphors by refluxing method

摘要

A novel refluxing method is presented to synthesize Eu3+ doped La2O2S phosphor nanocrystals. By the reaction of lanthanum formate and europium formate with sulfur powder in mixed solvents of triethylene tetramine and n-dodecanethiol under refluxing conditions for 12 h, pure Eu3+ doped La2O2S nanocrystals can be obtained. The sizes and morphologies of La2O2S: Eu3+ phosphors could be controlled from nanoflakes, micrometer vesicles, to spherical nanocrystals by adjusting the solvent ratios of n-dodecanethiol to triethylene tetramine. Excitation and emission spectra are used to characterize the as-synthesized nanocrystalline phosphors. Eu3+ occupies C3V site in Eu3+ doped La2O2S nanocrystals, which is the same as in bulky La2O2S: Eu3+ crystals. The fluorescent decay curves for 5D0→7F2 transition (624 nm) of Eu3+ doped La2O2S spherical nanocrystals show a long decay time τ1(1.2 ms) and a short decay time τ2 (0.4 ms), which embodies the fluorescent decay feature of nanosized phosphors.