Study On Preparation And Properties Of The Tungstate And Molybda Phosphors For White LED

Because of energy saving,environmental protection,long life,and a series of outstanding advantages,WLED?White Light Emitting Diode?becomes the most promising fourth-generation lighting source.At present,the main program to achieve white LED is fluorescent conversion method.The most widely used phosphor is the blue light In Ga N chip excited Y3Al5O12: Ce³⁺(YAG: Ce³⁺)yellow phosphor.But the yellow phosphor red light bias weak lead to poor color rendering?CRI?.For the purpose of improving the color rendering of white LED and reducing the color temperature to achieve the requirements of indoor lighting,the research of fluorescent materials should be strengthened to improve the luminous performance of the core components of the phosphor,especially the red phosphor.In this paper,rare earth luminescent Eu³⁺ is used as doping ion.Tungsten and molybdate is used as matrix.A series of tungsten and molybdate system fluorescent materials are synthesized by high temperature solid phase method and hydrothermal method.The luminous performance of phosphor is analyzed in detail.The main work is as follows:The matrix of Sr Mo O₄ and the phosphor of Sr Mo O₄: Eu³⁺ is successfully synthesized by high temperature solid phase method.The crystal structure of Sr Mo O₄ and the spectral properties of the phosphor and energy transfer of light-emitting ions are studied.The color coordinates is calculated.The chromaticity diagram is plotted.The optimum concentration of 30% is determined by adjusting the concentration of Eu³⁺.The effect of the flux and its doping on the luminescent properties of the phosphor is studied.The results show that the addition of flux Ba F2 reduces the crystal defect of the sample and increases the emission intensity by 4.5 times.And the synthesis temperature of the phosphor is decreased from 900? 4h to 600? 4h.It shows that the addition of flux Ba F2 reduces the energy loss greatly.The effects of charge compensator type and concentration on the luminescent properties of phosphor are studied.The result shows that the addition of Na2CO₃ can significantly enhanced the luminescence intensity by about 4.7 times when the best concentration is 9%.The WO₃?0.34H₂ O is successfully synthesized by hydrothermal method.The BaWO₄:Eu³⁺ phosphors are synthesized by hydrothermal method and high temperature solid phase method respectively.The spectral properties of the phosphors is discussed in detail.The result shows that BaWO₄: Eu³⁺ prepared by hydrothermal method has the same spectrum as that of high temperature solid phase method.By adjusting the concentration of Eu³⁺,the quenching concentration is determined to be 30%.The color coordinates of the sample is calculated as?0.530,0.447?.The color coordinates of the sample is plotte.This phosphor is a red phosphor that can be matched with the blue LED.And it can be doped in traditional white LED?blue LED + yellow phosphor YAG: Ce?to increase the red light emission to compensate for the low color rendering defects.