Synthesis Of SrAl₂O₄:Eu³⁺ Red Phosphor Prepared With Metal Chloride

The natural storage capacity of aluminosilicate is great and aluminosilicate is green 、 no pollution.At the same time,the synthesis process of rare earth aluminate phosphor is simple.The excitation and emission spectra region of strontium aluminate phosphors are very wide and strontium aluminate phosphors has stable chemical properties and good luminous performance;Currently,the research of red phosphor used in LED is not mature,so it has a very important significance to study strontium aluminate rare earth red phosphor.In this experiment,the precursor of SrAl₂O₄：Eu³⁺ red phosphor was prepared by chemical coprecipitation method,which can make the raw material mixed in the molecules or ions to obtain a finer powder;At the same time, the raw materials of rare earth ions use instead of the traditional rare earth oxide but its former level product rare earth chloride, reducing the cost、eliminating the need for rare earth chloride charging into rare earth oxide and using acid to dissolve rare earth oxide process, so as to shorten the process.The orthogonal experiment and single factor experiment were used to determine the main sequence and the best process parameters of the factors which affect the luminescent properties of SrAl₂O₄：Eu³⁺ red phosphor.The experimental results show that the PH value is the greatest influence on the luminescence intensity of the phosphor, followed by the addition of Eu3+,and then the amount of H3BO3 added, the holding time and the sintering temperature.The best process parameter determined by orthogonal test is that: PH is 7.5, the amount of incorporation of Eu3+ is 0.02 mol, the amount of H3BO3 is 3%, the holding time is 2h, the sintering temperature is1200 ℃.Compared with the process parameters obtained by the orthogonal experiment, only a parameter obtained by the single factor experiment is difference, namely, the sintering temperature is 1150 ℃.Single factor experiments were made to investigate the effect of various factors on the crystal structure 、the luminescence properties and morphology of phosphor,and the orthogonal experiment has only the luminescence intensity as the index, so the sintering temperature 1150 ℃ determined by the single factoris better.The excitation peak of SrAl₂O₄：Eu³⁺ red phosphors prepared by experiment is line in 395 nm, the emission peak is line in 619 nm.Studied on the effects and mechanism of phosphors’ performance when the alkali metal ions were added to the SrAl₂O₄：Eu³⁺ red phosphors.The results show that: alkali metal ion（Li+, Na+, K+） were added to the balance charge loss which caused by Eu3+ added and point defects which caused by Eu3+ insteaded of Sr2+,so the SrAl₂O₄：Eu³⁺ red phosphors which added alkali metal ions have higher emission intensity.At the same time, the intensity of the SrAl₂O₄：Eu³⁺ red phosphors doped with Li+ is the biggest, the intensity of the SrAl₂O₄：Eu³⁺ red phosphors doped with Na+ is the second, and the intensity of the SrAl₂O₄：Eu³⁺ red phosphors doped with K+ is the lowest,which mainly relate to ionic radius: Li+ has the smallest radius which makes Eu3+ enter the matrix easier.When the Li+ content is 0.04 mol, the luminescence intensity is the best.Studied on the effects and mechanism of phosphors’ performance when the matrix components was Changed.Mixed with Ba2+ 、 Ca2+, when the amount of Ca2+, Ba2+ is between 0.1 and 0.03 mol, the crystal structure of the fluorescent powder is still Sr Al2O4;when the amount of Ca2+, Ba2+ is between 0.4 and 0.9mol, the main phase of the phosphor were changed to Ca Al2O4 and Ba Al2O4.At the same time, the phosphors’ excitation peak and emission peak intensity which mixed with Ca2+ 、 Ba2+ is lower than SrAl₂O₄：Eu³⁺ phosphors’. And the emission peak of phosphors which doped Ca2+ shift to the long wave direction, this phenomenon called “red shift”;the emission peak of phosphors which doped Ba2+ shift to the short wave direction, appear "blue shift" phenomenon.