Preparation And Properties Of Eu³⁺:Tb₃Ga_5-xAl_xO₁₂ Orange-emitting Phosphors

The concept of sustainable development of energy conservation and environmental protection has gained worldwide consensus,and the concept of high efficiency,energy conservation and environmental protection is also followed in the lighting field.White light emitting diodes?WLED?will gradually become a new generation of light sources because they have advantages that traditional light sources do not have.At present,the research focus of synthesizing white light LED is white light synthesized by combining near-violet LED and fluorescent powder that can be efficiently excited by it.The more kinds of fluorescent powder used,the easier it is to synthesize white light with high color rendering index and appropriate color temperature.In this paper,a new type of high-efficiency Tb₃Ga₅O₁₂:Eu³⁺orange phosphor was synthesized.Tb₃Ga₅O₁₂:Eu³⁺phosphor was prepared by chemical coprecipitation and high-temperature solid-state method respectively.The advantages and disadvantages of the two methods for preparing Tb₃Ga₅O₁₂:Eu³⁺phosphor were systematically investigated.By means of X-ray diffraction,scanning electron microscope,thermogravimetric comprehensive thermal analysis,infrared spectrum analysis,excitation and emission spectrum,the optimal process conditions for preparing Tb₃Ga₅O₁₂:Eu³⁺phosphor were determined,and the properties of Tb₃Ga₅O₁₂:Eu³⁺phosphor were changed by Al³⁺doping.The orange fluorescent powder with excellent luminous performance,excellent thermal stability and high internal quantum efficiency is prepared.Finally,orange light emitting diode devices were fabricated and their practicability was tested.The main work and conclusions of this paper are as follows:?1?Tb₃Ga₅O₁₂:Eu³⁺phosphor was prepared by co-precipitation method,and its structure and luminescent properties were studied.When the pH value was maintained at 9and the Eu³⁺doping concentration was 5 mol%,the Tb₃Ga₅O₁₂:Eu³⁺phosphor prepared had the highest luminous intensity when calcined at 1200?for 4 h.The synthesized powder has a particle size of about 50 nm and has good dispersibility.Under the excitation of near-ultraviolet light at 379 nm,the strongest emission peak is located near 592 nm,which is attributed to the magnetic dipole transition to ⁵D₀/⁷F₁ of Eu³⁺ions,indicating that Eu³⁺ions occupy highly symmetrical sites in the main lattice.?2?The particle size distribution of the powder synthesized by the high-temperature solid-phase method is uniform and there is no obvious agglomeration.The Tb₃Ga₅O₁₂:Eu³⁺phosphor prepared by calcination at 1400?for 4 h has the highest luminous intensity.Compared with the phosphor prepared by chemical co-precipitation,although the calcination temperature is 200?higher,the luminous intensity is twice that of the powder by the liquid phase method.The luminescence thermal stability of Tb₃Ga₅O₁₂:Eu³⁺phosphor prepared by high-temperature solid-phase method was tested,and the activation energy was 0.250 eV.The internal quantum efficiency of Tb₃Ga₅O₁₂:Eu³⁺phosphor was measured to be 83.3%.?3?Tb₃Ga₅O₁₂:Eu³⁺phosphor is modified by Al³⁺ions doping.When the Al³⁺ions concentration is 12 mol%,the relative luminous intensity is maximized,which is 2.07 times the luminous intensity of the Tb₃Ga₅O₁₂:Eu³⁺sample that is not doped with Al³⁺ions.By testing the fluorescence decay curve of Tb₃Ga_5-x-x Al_xO₁₂:Eu³⁺phosphor,it was determined that the fluorescence lifetime was about 2.8 ms.By testing its temperature-varying spectrum,it was found that it has excellent optical thermal stability,its activation energy is0.244 eV,and the internal quantum efficiency of the phosphor is measured to be 95.6%.Finally,an orange light-emitting diode device was manufactured,indicating that Tb₃Ga_5-x-x Al_xO₁₂:Eu³⁺orange light-emitting phosphor has potential applications in near-UV pumped white light-emitting diodes.