Synthesis And Properties Of Rare Earth Ions RE³⁺?RE=Dy,Eu,Tb? Doped Gd₂?WO₄?₃ Phosphors With Colorful Emission

The solution of RE?NO₃?₃?RE=Gd,Tb,Dy,and Eu?and Na₂WO₄·2H₂O was used as the mother salt solution.The pH was adjusted by NaOH solution.Hydrothermal synthesis was usedtosynthesizetheprecursor.Aftercalcination,Gd₂?WO₄?₃:RE³⁺(RE³⁺=Tb³⁺,Dy³⁺,Eu³⁺,Dy³⁺/Eu³⁺,Tb³⁺/Eu³⁺,Dy³⁺/Tb³⁺)phosphors were synthesized.A series of performance characterization of Gd₂?WO₄?₃:RE³⁺phosphors were performed.Clever use of energy transfer between WO₄^2-?RE³⁺,Gd³⁺?RE³⁺,and rare-earth ions during co-doping,detailed study of RE³⁺(RE³⁺=Tb³⁺,Dy³⁺,Eu³⁺,Dy³⁺/Eu³⁺,Tb³⁺/Eu³⁺,Dy³⁺/Tb³⁺)doping The fluorescent properties of the hybrid Gd₂?WO₄?₃,Its innovative results are as follows:?1?the RE?NO₃?₃?RE=Gd,Tb,Dy,and Eu?and Na₂WO₄·2H₂O mixture is used as the mother salt solution.The pH was adjusted by NaOH solution,the precursor was synthesized using a hydrothermal method,and calcined to obtain a phosphor.The Gd₂?WO₄?₃:RE³⁺precursor and the phosphor have a similar functional group structure by FI-IR analysis,and the crystallinity of the precursor after calcination has been significantly enhanced;The doping of RE³⁺(RE³⁺=Tb³⁺,Dy³⁺,Eu³⁺,Dy³⁺/Eu³⁺,Tb³⁺/Eu³⁺,Dy³⁺/Tb³⁺)did not change the crystal structure of Gd₂?WO₄?₃ by XRD analysis;FE-SEM analysis shows that the precursor is basically flaky structure,and after calcination,the plate-like structure of precursor is maintained by fluorescent particles.?2?Gd₂?WO₄?₃:Dy³⁺(the concentration of Dy³⁺is 1 at.%-10 at.%)exhibits good yellow emission under excitation at 452 nm,its main emission peak is located at 574 nm,and Gd₂?WO₄?₃:Dy³⁺quenched at a concentration of 7 at.%of Dy³⁺,and its actual luminescent color was yellow consistent with its color coordinates?0.40,0.49?.Gd₂?WO₄?₃:Tb³⁺(concentration of Tb³⁺is 1 at.%-15 at.%)exhibits good green emission at 270 nm excitation,its main emission peak is at 547 nm,and Gd₂?WO₄?₃:Tb³⁺quenched at a concentration of 10at.%Tb³⁺.Its actual luminescent color is green and its color coordinates?0.33,0.60?are consistent.Gd₂?WO₄?₃:Eu³⁺(Eu³⁺concentration is 5 at.%-40 at.%)exhibits good red emission under excitation of 246 nm,its main emission peak is located at 617 nm,and Gd₂?WO₄?₃:Eu³⁺in Eu³⁺is obtained.The quenching occurred at a concentration of 30 at.%.The actual luminescent color was red and its color coordinates?0.67,0.33?were consistent.The quenching mechanism of Gd₂?WO₄?₃:RE³⁺(RE³⁺=Tb³⁺,Dy³⁺,Eu³⁺)is the interaction between rare-earth ions,and its fluorescence lifetime decreases with the increase of rare earth activated ions.The fluorescence temperature dependence of the material shows that:the Gd_1.93Dy_0.07?WO₄?₃,Gd_1.90Tb_0.10?WO₄?₃,and Gd_1.70Eu_0.30?WO₄?₃ phosphors did not change the shape and position of the excitation and emission peaks at different temperatures,the fluorescence lifetime has not changed,but the excitation and emission intensity decreases with the increase of temperature,and the three have higher activation energy.?3?In order to adjust the luminescent color of rare earth luminescent materials,Gd₂?WO₄?₃:RE³⁺(RE³⁺=Dy³⁺/Eu³⁺,Tb³⁺/Eu³⁺,Dy³⁺/Tb³⁺)phosphors were obtained by hydrothermal method through a series of preparation processes.When Dy³⁺/Eu³⁺is co-doped,the energy transfer functions of WO₄^2-?Eu³⁺,Gd³⁺?Eu³⁺,and Dy³⁺?Eu³⁺are applied.Under the excitation of 270 nm,the emission peaks of Gd₂?WO₄?₃:Dy³⁺/Eu³⁺are respectively located at⁴82 nm(Dy:⁴F_9/2-⁶H_15/2),⁵74 nm(Dy:⁴F_9/2-⁶H_13/2),⁵93 nm?Eu:⁵D₀-⁷F₁?,⁶16nm?Eu:⁵D₀-⁷F₂?,⁶53 nm?Eu:⁵D₀-⁷F₃?and⁷01 nm?Eu:⁵D₀-⁷F₄?,the phosphor gradually changes from yellow to red with the increase of Eu³⁺concentration.The actual luminescent color and color coordinates also change accordingly,and the Eu³⁺quenching concentration is10 at.%;The fluorescence lifetime of Gd₂?WO₄?₃:Dy³⁺/Eu³⁺phosphor at 574 nm decreased with the increase of Eu³⁺content under excitation of 270 nm,which also confirmed that Dy³⁺?Eu³⁺has energy transfer and energy of Dy³⁺?Eu³⁺.The transmission type is electric dipole-electric dipole interaction,and the maximum energy transfer efficiency of Dy³⁺?Eu³⁺is 60.1%.When Tb³⁺/Eu³⁺is co-doped,the energy transfer functions of WO₄^2-?Eu³⁺,Gd³⁺?Eu³⁺,and Tb³⁺?Eu³⁺are applied.Under the excitation of 246 nm,the emission peaks of Gd₂?WO₄?₃:Tb³⁺/Eu³⁺are respectively located in⁵47 nm(Tb³⁺:⁵D₄-⁷F₅),⁵93 nm(Eu³⁺:⁵D₀-⁷F₁),⁶16 nm(Eu³⁺:⁵D₀-⁷F₂),⁶53 nm(Eu³⁺:⁵D₀-⁷F₃),and⁷01 nm(Eu³⁺:⁵D₀-⁷F₄),with the increase of the concentration of Eu³⁺fluorescent powder by gradually changing to green yellow light then turn to turn red to orange red light,The final conversion to red light occurs.The actual luminescent color and color coordinates also change correspondingly,and the Eu³⁺quenching concentration is 20 at.%at 246 nm.The fluorescence lifetime of the excited Gd₂?WO₄?₃:Tb³⁺/Eu³⁺phosphor at 547 nm decreases with the increase of Eu³⁺content,which also confirms that Tb³⁺?Eu³⁺has energy transfer,and the energy transfer type of Tb³⁺?Eu³⁺is electric dipole The sub-electric dipole interaction,Tb³⁺?Eu³⁺maximum energy transfer efficiency of 31.8%.When Dy³⁺/Tb³⁺is co-doped,the energy transfer functions of WO₄^2-?Tb³⁺,Gd³⁺?Tb³⁺,and Dy³⁺?Tb³⁺are used.Under the excitation of 273 nm,the emission peaks of Gd₂?WO₄?₃:Dy³⁺/Tb³⁺are respectively located at⁴90 nm(Tb³⁺:⁵D₄-⁷F₆),⁵47 nm(Tb³⁺:⁵D₄-⁷F₅),⁵74 nm(Dy³⁺:⁴F_9/2-⁶H_13/2),⁵88 nm(Tb³⁺:⁵D₄-⁷F₄),⁶21 nm(Tb³⁺:⁵D₄-⁷F₃)and⁶63 nm(Dy³⁺:⁴F_9/2-⁶H_11/2),with the increase of Tb³⁺concentration,the phosphor gradually changes from yellow to green,and the actual luminescent color and color coordinates also change accordingly,and the quenching concentration of Tb³⁺at 7 at.%,the fluorescence lifetime of Gd₂?WO₄?₃:Dy³⁺/Tb³⁺phosphor at 574 nm decreases with the increase of Tb³⁺content under excitation of 273 nm,which also confirms that Dy³⁺?Tb³⁺has energy transfer and Dy³⁺?Tb³⁺.The type of energy transfer is electric dipole-quadrupole interaction,and the maximum energy transfer efficiency of Dy³⁺?Tb³⁺is 34.9%.