Luminescene Properties Of Rare Earth Ions Doped LaF₃ Micro/nano Crystals

The high quality rare earth doped upconversion luminescent nano-materials were prepared since the late 19th century,they have become a hotspot in some areas as photochemistry,biomedicine,materials science rapidly due to the superior chemical stability and unusual light stability proerties.Fluoride materials are considered to be one of the most efficient UCL matrix material because of low phonon energy,rare earth ions doped,wide range of transmittance of light.Therefore,lanthanide-doped micro/nano crystals were prepared with lanthanum fluoride used as matrix via solid state method,hydrothermal/solvent method and microwave hydrothermal method,respectively.The present work in details and summarized as follows:1.Different concentration LaF₃Er³⁺,LAF₃:Yb³⁺,Er³⁺,LaF₃:Yb³⁺,Tm³⁺ and LaF₃:Er³⁺,Tm³⁺ upconversion luminescence materials were synthesized by solid state reaction method with Re₂O₃?Re=La,Er,Yb,Tm?and NH₄HF₂ as precursors.X-ray diffractionand scanning electron microscope characterization results showed that the obtained products are single hexagonal phase LaF₃ with high crystallinity,the size of the particle is about 10 ?m.Meanwhile,the upconversion luminescence properties and energy transfer mechanism of the samples have been studied by doping rare earth ions concentration under 980 and 1550 run excitations.And the optimal doping concentrations of rare earth ions were obtained in each system,which provides abundant experimental data for other preparation methods.2.LaF₃:20%Yb³⁺,2%Er³⁺ nano upconversion luminescence materials were synthesized by hydrothermal/solvent method with Re?NO₃?₃?Re=La,Er,Yb?and NH₄HF₂?or NH₄F?as precursors.The influence of different solvents?deionized water and glycol?and fluorine source on the morphology,size and upconversion luminescence performance were studied.3.LaF₃:6%Er³⁺,5%Yb³⁺/0.3%Tm³⁺ nano upconversion luminescence materials was synthesized by microwave hydrothermal method with Re?NO₃?₃?Re=La,Er,Yb,Tm?and NH₄F as precursors by referring to the optimal doping concentration in system of excitation by 1550 nm.Compared to hydrothermal method,the reaction rate is improve due to its the faster heating speed.In addition,the results show that the productions were annealed at higher annealing temperature,which has greater luminescence performance with bigger partical size.The samples present strong near-infrared emission and the red emissi is enhanced by microwave hydrothermal method compared to that of solid-state reaction.