Preparation And Properties Of Ionic Liquid-Assisted Rare Earth Doped Phosphate

Ionic liquid assisted synthesis of nanocrystals is an effective method for preparing luminescent materials.Due to the stabilizing effect of the ionic liquid,the prepared material,which is one of the important components of fluorescent conversion white LED,has good luminescent properties with strong absorption capacity,high conversion efficiency,and strong emission capability in the ultraviolet-visible-infrared region and attracted many attentions.It has been shown that the ionic liquid-assisted phosphate phosphors have good absorption capacity and high luminescence conversion efficiency.In view of this,we had done the following work:1.Dihydrocholine phosphate ionic liquid?CDHP?was synthesized and characterized.2.Na₃Y?PO₄?₂:Eu³⁺phosphors were synthesized by hydrothermal method?with?NH₄?₂HPO₄ as a phosphorus source?and by ionic liquid-assisted hydrothermal method?with CDHP as a phosphorus source?.Fluorescence spectra of the materials prepared by the two methods show two main emission peaks at 593 nm and 615 nm under the excitation of 394 nm ultraviolet light.The addition of the ionic liquid improves the luminous efficiency of the phosphor.3.A series of Na₃Y_1-x?PO₄?₂:xTb³⁺phosphor materials were synthesized by ionic liquid-assisted hydrothermal method.We characterized the samples using XRD and SEM.SEM research shows Na₃Y?PO₄?₂ particles are rice-like materials with a length of 10-20?m and a particle size of 2-5?m.Fluorescence spectra of Na₃Y_1-x?PO₄?₂:xTb³⁺show four emission peaks at 490 nm,545 nm?dominantly?,586nm,and 624 nm under the excitation of 300-400 nm near-ultraviolet light,attributed to ⁵D₄-⁷F_J?J=6,5,4,3?transitions,respectively.Na₃Y_1-x?PO₄?₂:xTb³⁺phosphor has the strongest luminescence intensity when x is equal to 0.22,and of which the fluorescence lifetime is about 0.003 ms.Na₃Y?PO₄?₂:Tb³⁺has good stability and is a potential phosphor material for white LEDs.4.GreenNa₃Y?PO₄?₂:Ce³⁺,Tb³⁺phosphors weresynthesized byionic liquid-assisted hydrothermal method.Fluorescence spectra study show that Ce³⁺ions can effectively transfer the absorbed energy to Tb³⁺ions and sensitize Tb³⁺,which improves the luminous efficiency of phosphors.