Effect Of Rare-earth Ions Doping On The Fiuorescence Properties Of Zirconium Based Nanopowders

Rare-earth ions doped luminescent materials are widely used in LED lamps,optical sensors,biological imaging,luminescent display and other fields.Zirconium-based nanopowders have been widely studied for their excellent chemical stability and low phonon energy.Using the zirconium base as the substrate of the light-emitting material,the preparation method is hydrothermal method and sol-gel method.The fluorescence properties of rare-earth ions Eu³⁺,Tb³⁺,Tm³⁺,Ho³⁺and Er³⁺doped zirconium based nanopowders were studied.The effect of the charge compensator on the fluorescence properties of nanopowders,the energy transfer process between Eu³⁺and Tb³⁺,and the role of Yb³⁺-[WO₄]^2-dimer were also studied.The specific studies are conducted as follows:A series of Li⁺/Eu³⁺co-doped ZrO₂nanopowders were prepared by hydrothermal method.XRD results show that the doping of Li⁺and Eu³⁺does not affect the phase composition of cubic ZrO₂.Fluorescence spectroscopy indicates that the samples can be excited by the wavelength of 394 nm and 464 nm,resulting in red-orange emission at 592nm and 609 nm.The doping concentration of Eu³⁺affects the fluorescence intensity of the nanopowders,and the appropriate amount of Li⁺with valence compensation can improve the energy transfer efficiency.As can be seen from the CIE color diagram,these samples can emit red-orange light under the excitation of 394 nm,which has a very wide application prospects in the field of color display.A series of samples with substrate of 17 mol%Li Cl-33 mol%ZrO₂-50 mol%NH₄H₂PO₄were prepared by hydrothermal method.Different concentrations of Tb³⁺,fixed concentration of Eu³⁺and fixed concentration of Tb³⁺.Tb³⁺single-doped sample has a strong green emission peak at 544 nm.Eu³⁺single-doped samples have red-orange emission at 592 nm and 614 nm.The excitation wavelength of the co-doped sample was377 nm,and the emission spectra of the sample were studied.It was proved that the energy transfer existed between Tb³⁺-Eu³⁺ions,with Tb³⁺as the energy donor and Eu³⁺as the energy receiver.The CIE color map is drawn to show that by adjusting the concentration ratio of Tb³⁺/Eu³⁺to get the light-color adjustable nanopowders that can transition from green to red,which meets the needs of people and can be used in fields such as LED display and decoration.R³⁺/Yb³⁺/W⁶⁺（R=Tm,Ho,Er）doped ZrO₂nanopowders were prepared by the sol-gel method.Under 975 nm excitation,the three samples can emit single-colour up-conversion luminescence with high purity.The colour-purity of the three samples are 82%,93%and97%,respectively.The strong single-colour up-conversion emissionis due to the Yb³⁺-[WO₄]^2-dimer.The energy transfers of GSA(|²F_7/2,¹A₁>→|²F_5/2,¹A₁>)and ESA(|²F_5/2,¹A₁>→|²F_7/2,¹T₁/¹T₂>)play a key role in the up-conversion population processes.The research will be helpful for luminescence labeling,luminescence imaging and colour display domains.