Preparation And Research Of Phosphate-based Sr₉Y(PO₄)₇ LED Luminescent Materials

Due to the characteristics of the electronic configuration of the rare earth ion 4f,its compound has a variety of fluorescent properties,making rare earth a popular material in the field of phosphors.In view of the lack of sufficient red light components in the current emission spectrum of phosphors suitable for ultraviolet LED chips,it has become a hot spot to achieve spectral control and improve matching with LED chips.Therefore,this thesis takes Sr₉Y(PO₄)₇ as the research object,introduces the luminescent center into the matrix component through two methods of single doping and multi-doping activator,and studies its luminescence characteristics.It is expected to provide ideas for the production of red phosphors and spectrally adjustable phosphors.The results are as follows:The first part introduces two single-ion excitation systems of rare earth doped luminescent materials.Sr₉Y(PO₄)₇:Eu³⁺and Sr₉Y(PO₄)₇:Tb³⁺series single-doped red and green monochromatic phosphors prepared by high-temperature solid-phase reaction method.Under excitation at 394 nm and 267 nm,Sr₉Y(PO₄)₇:Eu³⁺and Sr₉Y(PO₄)₇:Tb³⁺exhibited the characteristic emission peaks of Eu³⁺(⁵D₀?⁷F₂,red 612nm)and Tb³⁺(⁵D₄?⁷F₅,green,542 nm),respectively.The variable temperature PL spectrum shows that the single-ion excitation system phosphor has good thermal stability,and the calculated activation energies of Eu³⁺and Tb³⁺for luminescence thermal quenching are 0.198eV and 0.291eV,respectively.The second part focuses on the energy transfer and temperature characteristics of the multi-ion excitation system of rare-earth-doped luminescent materials.With the increase of doped ions Mn²⁺,Tb³⁺content,Sr₉Y(PO₄)₇:Ce³⁺,Mn²⁺and Sr₉Y(PO₄)₇:Ce³⁺,Tb³⁺samples gradually transitioned from the blue region to the red and green regions,realizing the controllable adjustment of the luminous color.Research on the thermal stability of phosphors shows that the introduction of Ce³⁺improves the thermal stability of Mn²⁺and Tb³⁺.