Rare Earth Oxysalts Green/Red Fluorescent Material' Preparation And Optical Properties

Because of its excellent optical properties,rare earth oxalate,phosphate and molybdate materials were widely used in the synthesis of LED commercial phosphor.Since white LED is the use of red,green and blue the trichromatic LED chip combination to achieve,so research good color rendering index,strong color reproduction and high luminous efficiency LED chip tricolor phosphor is the most important thing for white LED.In this paper,the rare earth oxalates,phosphates and molybdates with excellent chemical stability were regarded as the research subjects.The green and red phosphors with good luminescence properties were successfully synthesized by means of conventional inorganic materials synthesis methods,and their fluorescence properties discussed in detail.This paper studies the green and red phosphors,mainly including the following three aspects:1.The Tb³⁺-doped Y₂?C₂O₄?₃ phosphors were prepared using the hydrothermal method in the presence of surfactants.XRD,SEM and FP were used to study the structure and luminescence properties of the material.When surfactant CA?Citric Acid?and pH 1.5 were employed,homogeneous cuboid-like structure product was obtained,and it showed higher luminescent intensity than phosphors prepared with surfactants EDTA,Glycine and PEG.Under the 370 nm radiation excitation,Y₂-x?C₂O₄?₃:xTb³⁺ phosphors exhibit green emission?546 nm?corresponding to the 5D4?7F5 transition of Tb³⁺.The luminescence intensity of Y₂-x?C₂O₄?₃:xTb³⁺ phosphors can be influenced by activator Tb³⁺doping concentration,and we can observe that the maximum luminescence intensity of the phosphor is at x=1.4.The corresponding concentration quenching mechanism is verified as quadrupole-quadrupole interaction.2.A series of Sr1-xZn₂?PO₄?₂:xSm³⁺ phosphors were synthesized with two calcination.Under the 407nm radiation excitation,the products show a strong red emission?601 nm?corresponding to the 4G5/2?6H7/2 transition of Sm³⁺ ions.By increasing the Sm³⁺ doped content,the maximum luminescence intensity of Sr1-xZn₂?PO₄?₂:xSm³⁺ phosphors is at x=0.2,with the activator increasing,the concentration quenching occurs.It is found that the dipole-dipole interaction is the major mechanism of concentration quenching for the Sr1-xZn₂?PO₄?₂:xSm³⁺?x>0.02?phosphors.By introducing the charge compensator R+?R=Li,Na,K?into the phosphor,the results indicate that the Na+ and K+ are able to enhance the luminescence intensity obtained product.In addition,the impact of fluxes?NH4F,H3BO3 and NaF?to the phosphors have been discussed.3.MY₂?MoO₄?₄:Sm³⁺,MY₂?MoO₄?₄:xSm³⁺,yEu³⁺?M=Ca,Sr and Ba?and CaY₂?MoO₄?₄:Sm³⁺,Mn²⁺ phosphors were successfully prepared using a simple solid-state reaction route,and their luminescent properties and energy transfer process from Sm³⁺ to Eu³⁺ and Sm³⁺ to Mn²⁺were systematically investigated.The results indicate that MY₂?MoO₄?₄:Sm³⁺phosphors can be effectively excited by UV light 407 nm originating from the 6H5/2?4F7/2 transition of Sm³⁺,and exhibit a satisfactory red emission of Sm³⁺ about 646 nm,in which the emission intensity of SrY₂?MoO₄?₄:Sm³⁺ is the strongest among the MY₂?MoO₄?₄:Sm³⁺?M=Ca,Sr and Ba?.For Eu³⁺ co-doped MY₂?MoO₄?₄:Sm³⁺ samples,with Eu³⁺ doping content increasing,the main emission peaks of Sm³⁺ are decreased,but the emission peaks and intensity of Eu³⁺are increased while the maximum intensity of luminescence at the Eu³⁺ concentration 0.9.The introduction of Eu³⁺ in the MY₂?MoO₄?₄:Sm³⁺ phosphors can remarkably generate a strong emission line at 616 nm,originating from the 5D0?7F2 transition of Eu³⁺ and Sm³⁺?4G5/2??Eu³⁺?5D0?effective energy transfer process.The energy transfer mechanism from Sm³⁺ to Eu³⁺ was discussed in detail.In Sm³⁺-Mn²⁺ co-doped CaY₂?MoO₄?₄ phosphor,with Mn²⁺doping,it occurs energy transfer from Mn²⁺ to Sm³⁺,so enhanced the fluorescence intensity of phosphor.