Preparation And Properties Research Of Oxonitride Phosphor(Sr_1-xBa_x)_2.97SiO₃N_4/3:0.03Eu²⁺

Oxonitride(M-Si-O-N) phosphor developed as new member of phosphors in recent years. With special Si(O/N)4 tetrahedron forming three-dimensional network structure, oxonitrideosilicate not only has excellent photoluminescence properties, but also has excellent chemical stability and thermal stability. Among them, the orange and red oxonitrideosilicate phosphors are preferred by scientific research scholars, specially. It aims to make up for red component shortage of white LED,which will lead to the high color temperature and low color rendering index. In this study, a novel orange-red oxonitrideosilicate phosphor(Sr1-xBax)2.97SiO3N4/3:0.03Eu2+(SBSON) was synthesized by solid-state reaction in a reducing atmosphere. The samples were characterized by X-ray diffraction(XRD), Scanning Electron Microscope(SEM) and fluorescence spectrophotometer. We studied the synthesis system, made a preliminary analysis on its crystal structure and explored the influence of different concentrations of Ba2 + ions doping on crystal structure, microstructure and fluorescence properties of Sr2.97 SiO3N4/3:0.03Eu2+(SSON). Research indicated:The samples prepared at 1550 ? for 4h generates good luminescent intensity and high purity. SSON is isostructural with Sr3SiO5(JCPDS No.26-0984), having tetragonal crystal system, P4/ncc space group. The results of Rietveld refinement indicates that a=b=6.9506 ?,c=10.75977 ?,V=519.813 ?3and the final correction factor Rp = 6.0%, Rwp = 7.9%, ?2 = 8.88. Compared to the initial model Sr3SiO5, lattice volume of SSON is some reduced, which can be attributed to the replacement of smaller Eu2+(rEu2+=1.17?) with Sr2+(rSr2+=1.18?) and unequal amounts replacement between N3- and O2-. At the same time, we investigated the fluxes and found that both BaF2 and NH4 Cl could improve luminescence properties of phosphor SSON.SBSON(x?0.5) are still isostructural with Sr3SiO5. With the increasing of Ba2+ content, the diffraction peaks intensities decline and the unit cell volume has a trend of shrinkage(x=0.05, x=0.1) first and then linearly expansion(x?0.2). Through the doping of Ba2+ ions, the particle morphology, luminescence intensities and thermal stability are all improved obviously. With the doping of Ba2+ up to x=0.2, the grains are crystallized toward nearly spherical morphology and the size is 3-10 um. When the x equals 0.5 the luminescence intensity reaches maximum which is about 1.48 times as that of the phosphor free of Ba. The emission peaks can be tuned from 583 nm to 601 nm by adjusting Ba2+ content. Besides, the doping of Ba2+(x=0.4) can also prolong the average lifetime from 1482 to 2122 ns. With high emission intensity and thermal stability, SBSON shows potential application in white LEDs.