Syntheses And Photoluminescence Properties Of Rare Earth Zirconate System Phosphors

Rare earth ions can produce a large number of radiation and fluorescence spectrums information because of the electron transitions of 4f between the configuration of f-f and f-d.They can emit electromagnetic radiation of various wavelengths from ultraviolet light,visible light to infrared light,and they have many luminous characteristics such as high luminous intensity,bright colors,strong light absorption and emission wavelength tunable,and so on.So in recent years,rare earth inorganic luminescent materials have become an indispensable part in lighting,adisplay,optical communication,medical imaging and other fields.In the new era,research and preparation of high-performance phosphor has become a critical issue in the field of luminescent materials.On account of the chemical and physical properties of rare earth materials,zirconate?Gd₂Zr₂O₇,Y₂Zr₂O₇?matrix photoluminescence was synthesis by hydrothermal method.Doping activating ions(Eu³⁺,Tb³⁺)to realize the red and green light emission,and discuss the different surfactants in improving the role of the phosphor luminescence performance.The main research is focused on the below topics:1.The Gd₂Zr₂O₇:Eu³⁺ red phosphors were prepared by hydrothermal method,and optimum doping ratio of Eu³⁺ concentration was explored.X-ray diffractometer?XRD?,scanning electron microscopy?FE-SEM?,fluorescence spectroscopy?PL?were used to analyze the phosphor's phase composition,microstructure and luminous performance.The XRD patterns showed that all the diffraction peaks were assigned well to the standard card of Gd₂Zr₂O₇?JCPDS no.16-0799?,confirming its orderly pyrochlore structure of crystal microstructure.The FE-SEM confirmed that the diameter of the nanorods was about 300 nm and the length of about 2000-3000 nm.The PL datas indicated that the intensities of emission peaks gradually increased and reached a maximum When the doping concentration of Eu³⁺ at 0.04.Then the luminescence intensities decreased for additional Eu³⁺ substitution.This phenomenon was due to concentration quenching effect.The explanation of the phosphor luminescence mechanism and the influence factors were discussed in detail to optimize the experiment processing.2.The Gd₂Zr₂O₇:Tb³⁺ phosphor was synthesized by hydrothermal method.The experiment results were investigated by XRD,FE-SEM,TEM and PL.The result confirmed that one-dimensional Gd₂Zr₂O₇:Tb³⁺ nanorods with diameter of about 30 nm and length of 150-300 nm were formed.PL study revealed that Gd₂Zr₂O₇:Tb³⁺phosphors presented dominant green emission,which was attributed to the transitions from5D4 excited states to7FJ?J=3-6?ground states of Tb³⁺.The strongest emission peaks appeared at 545 nm?5D4?7F5?,and an obvious concentration quenching was observed when Tb³⁺ion concentration was 5 at.%.The effects of cross-relaxation between Tb³⁺on luminescence intensity and optical purity were discussed.The sample of?Gd0.95Tb0.05?₂Zr₂O₇ was prepared by high temperature solid state method and the microstructure was irregular polygon,uneven size,luminous intensity slightly higher than the hydrothermal method.3.The Y₂Zr₂O₇: Tb³⁺green phosphors were prepared by hydrothermal method.PL shown that the strongest emission peak of?Y1-x Tbx?2ZrO7 phosphor was attributed to the transitions of5D4?7F5?545 nm?of Tb³⁺.The distance between every Tb³⁺in concentration quenching was calculated by formula and drew a conclusion that the cross-relaxation was the main reason.Different magnification FE-SEM images confirmed that the products' structure was the hollow tubular,with internal diameter of about 80-130 nm,wall thickness about 30-70 nm and length between 3-5 ?m.The narrow dispersed and morphology regularity nanorods used as phosphors may be promising.4.In the premise of acknowledge about optimal doping ratio of the Y₂Zr₂O₇:Tb³⁺phosphor.There were four types of surfactants added into that superlative as-product,like Sodium dodecyl benzene sulfonate?SDBS?,sodium dodecyl sulfate?SDS?,nonionic surfactant Povidone?PVP?,and organic salts ethylenediamine tetraacetic acid disodium?EDTA?,to improve the phosphor luminescence.The microstructure of samples with different surfactants was nanorods.Compared with the non-added sample,surfactants can significantly improve the light absorption capacity,quantum efficiency and luminescence intensity of the phosphors.The luminous intensity of doped with surfactant of EDTA was seven times than that of pristine sample,possessing nanorod's microstructure,uniform size,and smooth surface,which revealed extraordinary application in superior performance phosphors.