Synthesis and Characterization of Upconversion FluorescentYb3+,Er3+Doped CsY2F7Nano- and Microcrystals

[摘要] CsY2F7: 78%  Y3+, 20%  Yb3+, 2%  Er3+nanocrystals with a mean diameter of approximately 8 nm were synthesized at  185°Cin the high boiling organic solventN-(2-hydroxyethyl)-ethylenediamine (HEEDA) using ammonium fluoride, the rare earth chloridesand a solution of caesium alkoxide ofN-(2-hydroxyethyl)-ethylenediamine in HEEDA. In parallel with this approach, a microwave assisted synthesis was carried out which forms nanocrystals of the same material,about 50 nm in size, in aqueous solution at200∘C/8 bar starting from ammonium fluoride, the rare earth chlorides, and caesium fluoride. In case of the nanocrystals, derived from the HEEDA synthesis, TEM images reveal that the particles are separated but have a broad size distribution. Also anoccurred heat-treatment of these nanocrystals (600∘Cfor 45 minutes) led to bulk material which shows highly efficient light emission upon continuous wave (CW) excitation at 978 nm. Besides the optical properties, the structure and the morphology of the three products were investigated by means of powder XRD and Rietveld method.

[学科分类] 材料工程