Preparation And Properties Of Biochar Based Bismuth Bromide Oxide Composite Photocatalyst

White LED has become a new generation of solid-state lighting light source with the advantages of energy saving,environmental protection and high reliability,but its phosphors have some problems,such as poor coloring purity,low luminous efficiency and poor luminous stability,so it is of great significance to find a commercial phosphor with high color purity and good stability.Therefore,in this paper,Eu³⁺,Tb³⁺,Sm³⁺were used as doping ions,Ba WO₄,Ba La₂WO₇,La BWO₆were selected as matrix materials,white LED phosphors were prepared by high temperature solid state method,and the structure and luminescence properties of the samples were studied by XRD and PL.The content is as follows:1.Ba WO₄:Eu³⁺phosphors were prepared by high temperature solid state method,the optimum calcination temperature was 1200?,and the best(mol),concentration quenching of13%Eu³⁺was electric quadrupole-electric quadrupole interaction.Under the excitation of463nm blue light,the strongest emission peak is 617nm,which belongs to the electric dipole transition of Eu³⁺from ⁵D₀to ⁷F₂.The optimum doping amount of Ba WO₄:0.05Eu³⁺x Tb³⁺is0.07,and the concentration quenching is electric dipole-electric dipole interaction.Under the excitation of 394nm ultraviolet light,there are two emission peaks of 545nm and 616nm,which are the ⁵D₄to ⁷F₅transition of Tb³⁺and the ⁵D₀to ⁷F₂transition of Eu³⁺.There is energy transfer between Tb³⁺and Eu³⁺,and the mechanism is electric dipole-electric dipole interaction.The color coordinates showed that with the increase of Tb³⁺concentration,the color coordinates gradually changed from light yellow to green and back to light yellow.2.Ba La₂WO₇:Eu³⁺phosphors were prepared by high temperature solid state method,the optimum calcination temperature was 1300?,and the best(mol),concentration quenching of10%.Eu³⁺was electric quadrupole-electric quadrupole interaction.Under the excitation wavelength of 394nm,the strongest emission peak is 621nm,which belongs to the electric dipole transition of Eu³⁺from ⁵D₀to ⁷F₂.The optimum doping amount of Ba La₂WO₇:0.05Eu³⁺,x Sm³⁺is 0.05,and the concentration quenching is due to the electric dipole-electric dipole interaction.The color coordinates show that the color coordinates of double doped phosphors are closer to the red region than that of single doped Eu³⁺,which indicates that Sm³⁺as a sensitizer transfers energy to Eu³⁺.3.La BWO₆:Eu³⁺phosphors were prepared by high temperature solid state method.The optimum calcination temperature was 1000?.The quenching mechanism of 9%(mol),concentration of Eu³⁺was electric dipole-electric dipole interaction.Under 394nm excitation,the strongest emission peak is 620nm,which belongs to the electric dipole transition of Eu³⁺from ⁵D₀to ⁷F₂.The best doping concentration of La BWO₆:0.05Eu³⁺,x Tb³⁺is x=0.07,546nm emission peak of Tb³⁺and 592nm and 618nm emission peak of Eu³⁺were obtained under UV excitation of 278nm.There is energy transfer between Tb³⁺and Eu³⁺.With the increase of Tb³⁺concentration,the corresponding fluorescence color changed gradually from yellow to green.