Synthesis And Luminescence Properties Of Rare Earth Doped Perovskite-type ABO₃ Luminescence Powder

The perovskite structure oxide has a great variety of crystals and can be replaced by a large number of ions.Therefore,the perovskite structure luminescent matrix materials show a potential application prospect in solid-state lighting,electronic display,detection and other fields.The optical properties of rare earth doped perovskite-type oxides are also favored by many researchers.Therefore,the optical properties of rare earth doped perovskite oxides are favored by many researchers.In this paper,a series of Rare earth doped perovskite ABO₃(A=Ca,Gd,La,B=Ti,Al,RE=Eu³⁺,Er³⁺,Yb³⁺)phosphors were prepared by sol-gel combustion method and hydrothermal method respectively.The crystal structure,morphology and luminescent properties of the phosphor were studied by XRD,SEM,fluorescence and upconversion luminescence spectra.The main contents and analysis results are as follows:1.LaAlO₃:Eu³⁺and GdAlO₃:RE³⁺（RE=Eu/Er-Yb）phosphors prepared by sol-gel combustion method.A series of LaAlO₃:Eu³⁺,GdAlO₃:RE³⁺（RE=Eu/Er-Yb）phosphors were prepared by sol-gel combustion method.The effects of molar ratio of citric acid to rare earth ions（CMMR）,heat treatment temperature and doping ions on the structure,crystal phase and luminescent properties were studied.The results show that the proper amount of citric acid and higher heat treatment temperature are conducive to the synthesis of GdAlO₃:RE³⁺（RE=Eu/Er-Yb）phosphors with orthogonal structure and LaAlO₃:Eu³⁺phosphors with hexagonal structure.When CMMR is 1:1,GdAlO₃:Eu³⁺emits strong red light,and the lattice symmetry of Eu³⁺is high.The strongest emission peaks of LaAlO₃:Eu³⁺,GdAlO₃:Eu³⁺phosphors belong to ⁵D₀→⁷F₂transition of Eu³⁺,but the emission patterns are different.Compared with GdAlO₃:Eu³⁺phosphor,LaAlO₃:Eu³⁺phosphor has a higher local symmetry lattice.The GdAlO₃:Er³⁺,Yb³⁺phosphors synthesized with CMMR of 1:1 show red and green emission peaks under 980 nm laser excitation,while the green emission is stronger.The color coordinates calculated of samples show that GdAlO₃:Eu³⁺,LaAlO₃:Eu³⁺and GdAlO₃:Er³⁺,Yb³⁺are red,orange red and green.2.Ca_1-xGd_xTiO₃:Eu³⁺and CaTiO₃:Er³⁺,Yb³⁺phosphors prepared by sol-gel combustion method.Ca_1-xGd_xTiO₃:Eu³⁺,CaTiO₃:Er³⁺and Yb³⁺phosphors were prepared by sol-gel combustion method.The effects of molar ratio of citric acid to rare earth ions（CMMR）,heat treatment temperature and Gd³⁺doping on the structure,crystal and luminescent properties were studied.The results show that the proper amount of citric acid and higher heat treatment temperature are conducive to the synthesis of orthorhombic Ca_1-xGd_xTiO₃:Eu³⁺and CaTiO₃:Er³⁺,Yb³⁺phosphors with good crystallinity.With the increase of Gd³⁺doping ratio,the lattice distortion occurs,the crystallinity of CaTiO₃:Eu³⁺samples decrease,and the CaTiO₃phases changes to Gd₂Ti₂O₇phases.The luminescence intensity of the main peak of CaTiO₃:Eu³⁺phosphor prepared by heat treatment at 800℃is the strongest.The increase of heat treatment temperature improves the symmetry of Eu³⁺lattice.With the increase of Gd³⁺doping ratio,the luminescence intensity first increases and then decreases.The luminescence intensity of the sample with 15%Gd³⁺doping ratio is the strongest,while Eu³⁺is in a low local symmetry lattice.Under 980 nm excitation,the spectrum of CaTiO₃:Er³⁺,Yb³⁺phosphors consists of 510～585 nm green emission and 630～710 nm red emission,and the emission patterns is almost the same.The relative intensity of red light and green light of the sample decreases with the increase of heat treatment temperature,and the color coordinate of the sample moves to the green light region.At 700℃and 800℃,with the increase of Gd³⁺doping ratio,the luminescence intensity decreases,the relative intensity of red and green light increases,and the color coordinate of the sample moves to the red region.3.CaTiO₃:Eu³⁺luminescent powder by hydrothermal methodCaTiO₃:Eu³⁺phosphors were prepared by hydrothermal method.The effects of ratio of alcohol to water,reaction temperature and reaction time on the crystal structure,morphology and luminescent properties of the phosphors were studied.The results show that higher temperature and longer hydrothermal reaction time are conducive to the synthesis of orthorhombic CaTiO₃:Eu³⁺phosphors.The results show that the proper ratio of alcohol to water promotes the complete growth of the crystal structure,and the morphology of the samples tends to be regular four-prism.With the increase of ratio of alcohol to water,the excitation intensity and emission intensity of the sample increase gradually.When the ratio of alcohol to water is increase,the crystal growth of the sample is complete and the crystal defects are reduced,which provides a better crystal field for Eu³⁺,making the local environment of Eu³⁺conducive to energy transfer and the absorption of excitation light,so as to improve the luminescence intensity of the sample.The relative emission intensity ratios of ⁵D₀→⁷F₂and ⁵D₀→⁷F₁calculated by emission spectra show that the local environment of Eu³⁺ions is related to the ratio of alcohol to water.