Luminescent Properties Of Phosphors Doped By Eu Ion For Near-Ultraviolet Excitation

In this paper, some phosphors which could be excited by UV-LED （Ultraviolet-LightEmitting Diode） were prepared by high temperature solid-state reaction. There is a studybased on the best synthesized condition, the best doped concentration of impurity and thecrystal structure of the samples. From the test of the excitation and emission spectra, we studytheir luminescent properties. The chief contents are given as follows:（1） Ba2-xCa（PO4）2:xEu²⁺blue-emitting phosphors were prepared. There is a study basedon the doped concentration of Eu²⁺, the length of sintered time and the synthesizedtemperature which effect on the luminescent properties. XRD indicates that the samples havea little shift in the direction of larger diffraction degree by adding the quantity of Eu²⁺ion.They exhibit wide blue emission spectra at455nm excited by365nm. It is found that the bestsynthesized condition is T4, and the best doped concentration of Eu²⁺is0.04for the phosphor.The study points out that the mechanism of the concentration quenching effect is the electricdipole-dipole interaction.（2） Sr1-xBaxAl2O4:Eu²⁺phosphors were synthesized. The patterns of XRD indicated thatthere were two kinds crystal structures of the monoclinic phase of SrAl2O4and the simplehexagonal phase of BaAl2O4in the samples when x varied. As they were excited by360nm,the emission spectra gradually changed from single green emission （λmax=516nm） toblue-green dual-emission （λmax1=441nm, λmax2=486nm） with the increase of x. There was agood property in Sr0.5Ba0.5Al2O4:Eu²⁺. We get the maximum dual-emission intensity whenconcentration of Eu²⁺is0.29%. and the study points out that the mechanism of concentrationquenching effect is the electric dipole-dipole interaction.（3） BaMg2（PO4）2:Eu3+phosphors were synthesized. XRD indicates the sample is purephase of BaMg2（PO4）2crystal structure. The sample fits UV-LED chip excitation, and themajor emission peaks locate at595nm （⁵D₀�'^<sup>7F_<sub>1）,614nm （⁵D₀�'^<sup>7F_<sub>2） and700nm（⁵D₀�'⁷F₄）. The increase of Eu3+concentration prompt the transition of⁵D₀�'⁷F₁and inhibitethe transition of⁵D₀�'⁷F₂relatively. Charge compensation results show that incorporation ofLi⁺, Na⁺and K⁺could increase the emission intensity. Enlarging ionic radius of compensationcould improve the probability of electric dipole allowed⁵D₀�'⁷F₂transition. （4） The charge compensated phosphors BaMg1.99-x（PO4）2:0.01Eu3+,xN+（N=Li,Na,K）were synthesized. There were a brief analysis of valence stability of Eu3+and the effects of thecharge compensators （Li⁺, Na⁺and K⁺ions） upon the crystal structures and luminescenceproperties of BaMg1.99（PO4）2:0.01Eu3+in this paper. XRD patterns showed that theintroduction of charge compensation influenced the crystal phases. Eu3+single-doped in thesamples would be transformed into Eu²⁺possibly because of the valence instability. From theresults of the emissions affected by charge compensators, it was known that the addition ofappropriate Li⁺ions could increase the probability of the orange light emission （⁵D₀�'⁷F₁）,while the addition of appropriate K⁺ions could increase the probability of the red lightemission （⁵D₀�'⁷F₂）.