Preparation And Spectrum Property Of Rare Earth Doped Nitride Phosphors

The LED is called a new generation of solid state illumination light source,it not only has a series of advantages,such as rapid response,high seismic resistance,high efficiency,small volume and environmental friendliness,but also expands the application field and scope of white light LED.Rare-earth doped nitride phosphor is a kind of outstanding fluorescent conversion materials which can be used in white LED,because it has the advantages of high efficiency and stability.However,the synthesis conditions of nitride phosphors are very strict,moreover,the requirements of the experimental equipment are sophisticated and the energy consumption is large.This paper selected three kinds of nitride phosphors doped with different rare-earth elements as the research object,and the influence factors about their structure and fluorescence properties were discussed.And also discussed a method of preparing nitride phosphors with lower cost and better process.Using CaH₂,AlN and Si₃N₄ as the main material,Ca_1-x-x AlSiN₃:xEu²⁺red phosphors,Ca_1-xAlSiN₃:xYb²⁺red phosphors and Ca_1-xAlSiN₃:xCe³⁺yellow phosphors were synthesized by carbothermal reduction nitridation under atmospheric pressure.At the same time,the influence factors such as the amount of graphite powder,the doping concentration of rare-earth ions,the reaction temperature and the holding time were discussed.Finally,the samples were analyzed by X-ray diffraction,excitation spectrum,emission spectrum,fluorescence lifetime attenuation curve and color coordinate.The results are as follows:Under the precondition of the reaction temperature was 1550℃,the holding time was 6h,C/O=0.88.The Ca_1-x-x AlSiN₃:xEu²⁺red phosphor has the best luminescence performance when the doping concentration of Eu²⁺ion was x=0.08,the diffraction peak position of the prepared sample was the same as that of the standard card,under the excitation of 460nm wavelength,the main emission peak was at 665nm,it showed the red emission and the strongest luminous intensity,and the fluorescence lifetime was 1.064μs and the color coordinate was（0.6603,0.3400）,this is very close to the ideal red light standard value（0.67,0.33）specified by the National Standard Committee（abbreviated as:NTSC）.The Ca_1-x-x AlSiN₃:xCe³⁺yellow phosphor has the best luminescence performance when the doping concentration of Ce³⁺ion was x=0.06,the diffraction peak position of the prepared sample was the same as that of the standard card,and under the excitation of 460nm wavelength,the main emission peak was at 585nm,which indicated the yellow emission and the strongest luminous intensity,the fluorescence lifetime was 0.126μs and the color coordinate was（0.4699,0.5099）,this is very close to the ideal red light standard value（0.479,0.520）specified by the NTSC.The Ca_1-xAlSiN₃:xYb²⁺red phosphor has the best luminescence performance when the doping concentration of Eu²⁺ion was x=0.01,the diffraction peak position of the prepared sample was the same as that of the standard card,and under the excitation of 528nm wavelength,the main emission peak was at 629nm,which showed the red emission and the strongest luminous intensity,the fluorescence lifetime was 1.042μs and the color coordinate is（0.6603,0.3400）,belong to the region of red light.This study selected CaH₂ as calcium source to introduce Ca instead of the inert raw material Ca₃N₄,which reduced the synthesis temperature and pressure of nitride phosphors,optimized the preparation conditions.Compared with other methods for the synthesis of nitride phosphors,the method used in this paper makes it easier for phosphors to produce nitride phosphors with good properties by using the existing equipment.