Preparation And Luminescent Properties Of Rare Earth Doped NASICON Phosphors

White LEDs have attracted the attention ofresearchers because of their high reliability,long life and environmental protection.At present,the main production scheme of white LED on the market is the electro-optical-light conversion method of LED chip with phosphors.It can be seen that the phosphor has a great influence on important parameters such as the life,color temperature and color rendering index of the white LED.Especially for red phosphors,how to improve the luminous efficiency and stability of phosphors is the direction of the efforts of researchers.The purpose of this research is to develop a new type of rare earth doped red phosphor.?1?Na₃Zr₂Si₂PO₁₂:Eu³⁺phosphor was prepared by high temperature solid phase method.The structure and luminescence properties of theEu³⁺doped samples were studied in detail.Under the excitation of 394 nm,591 nm orange light and 619 nm red light were emitted.The optimum doping concentration is 24%.The concentration quenching mechanism is attributed to the electric quadrupole-electric quadrupole interaction with a thermal activation energy of 0.504 eV.The reactant Li₂CO₃ was added as a charge compensator,and the luminescence intensity was enhanced.LED devices fabricated with Na_2.76Zr₂Si₂PO₁₂:0.24 Eu³⁺and commercial green powder and UV chips have a color rendering index of 75.6 and a color temperature of 6358 K.The color rendering index has room for further improvement.Na_3-xZr₂Si₂PO₁₂:xEu³⁺is expected to be used as a new type of red phosphor in UV-excited white LED products.?2?Na₃Zr₂Si₂PO₁₂:Tb³⁺and Na₃Zr₂Si₂PO₁₂:Eu³⁺,Tb³⁺phosphors were synthesized by high temperature solid phase method.Study its crystal structure,luminescence properties,concentration quenching and energy transfer.As the concentration of doped Tb³⁺ions increases,the intensity of the emitted light first increases and then decreases.The optimal doping concentration of Tb³⁺is 12%.The concentration quenching mechanism is the electric quadrupole-electric quadrupole interaction.At 375 nm,the main emission peaks are located at 489 nm,545 nm,584nm,and 622 nm.Li⁺is added as a charge compensation,and the luminescence intensity is enhanced.The decay lifetime decreases as Tb³⁺increases.The luminescence intensity of the sample Na_2.88Zr₂Si₂PO₁₂:0.12Tb³⁺weakened with the increase of temperature,and the sample activation energy was E=0.295eV.With Na₃Zr₂Si₂PO₁₂:Eu³⁺,the decay lifetime of Tb³⁺decreases with the increase of doping ions,and energy transfer from Eu³⁺to Tb³⁺proves to be electric dipole-electric dipole moment interaction;it has good temperature thermal stability.The results show that Na₃Zr₂Si₂PO₁₂:Eu³⁺,Tb³⁺have the potential to be used as a red phosphor for white LEDs.?3?Na₃Zr₂Si₂PO₁₂:Sm³⁺and Na₃Zr₂Si₂PO₁₂:Eu³⁺,Sm³⁺phosphors were synthesized by high temperature solid phase method.The crystal structure,luminescence properties,energy transfer and temperature stability were studied.At the wavelength of 404 nm,the Sm³⁺-doped samples have main characteristic peaks at560 nm,599 nm and 642 nm,with Sm³⁺doping.When the concentration is increased,the intensity of the emitted light is firstly enhanced and then weakened,and the corresponding maximum doping concentration is 14%.The concentration quenching mechanism is an electric dipole moment-electric dipole interaction.The decay lifetime decreases monotonously with the increase of doped Sm3+ions,and has good heat quenching resistance.With Na_2.92-xZr₂Si₂PO₁₂:0.08Eu³⁺,xSm³⁺the decay lifetime of decreases with the increase of doping ions,and there is energy transfer from Sm³⁺to Eu³⁺,and it is proved to be electric dipole moment-electric quadrupole moment interaction;The temperature is weakened and the temperature is good.Na₃Zr₂Si₂PO₁₂:Eu³⁺,Sm³⁺is expected to be used as a phosphor for white LEDs.