Effects Of B₂O₃ On The Synthesis And Properties Of Sr₄Al₁₄O₅₁:Eu～(2+), Dy～(3+)

The long lasting phosphorescent materials, strontium aluminates phosphors, with high brilliance, long afterglow and stable performance, has been widely used in emergency illumination, marks, displaying and so on. But the synthesis temperature of strontium aluminates phosphors is very high, which cause the difficulties of synthesis and triturating, and the decreasing of material phosphor properties, and even the impeding of applications for the materials. Primary investigations show that the synthesis temperature can be reduced by adding B₂O₃, and the luminescent properties can also be improved, but the affecting mechanism of B₂O₃ on the preparation and luminescent properties has not been understood clearly. In this paper, by adding B2O3 and adjusting the synthesis process, Sr₄Al₁₄O₅₁:Eu²⁺Dy³⁺ phosphors were synthesized at lower temperature by means of solid reaction method, and the influences of B₂O₃ on preparation process and luminescent properties of this material have been investigated, too.In detail, we investigated the influences of synthesis temperature andflux on the luminescent properties of Sr₄Al₁₄O₅₁:Eu²⁺,Dy³⁺ phosphors, optimized the synthesis technology and reduced synthesis temperature about 100℃. The long lasting blue-emitting luminescent material, Sr₄Al₁₄O₅₁:Eu²⁺,Dy³⁺, with long after-glow for 24 hours, has been synthesized at 1250℃ and with flux of 12.5% B₂O₃. It is obvious that the synthesis technology and products reported above are useful, so the expected result, reducing the synthesis temperature of aluminates phosphor, is obtained.It is found that the effect of B₂O₃ content on luminescent properties depends on the synthesis temperature. At low synthesis temperature, the increasing of B₂O₃ content induce better luminescent brightness of samples, while at high synthesis temperature, better luminescent brightness can only be obtained when B₂O₃ content is low. The flux, B₂O₃ may change the forming process of resultants, accelerate the synthesis process and then change the emission color. Results of X-ray diffraction show that the resultant synthesized at 1250℃ consists of three kinds of substances when no or little B2O3 is added, the main is the yellow-green emitting SrAl₂O₄, the second is Sr₄Al₁₄O₅₁ and the last one with excess aluminum. With the increasing of B2O3, synthesis process is accelerated and reactant with perfect crystalline is formed, so the resultants with stable Sr4Ali4O25 and less SrAl2O4 can be obtained.What more, a new substance whose emission wave length is 460nm has been observed, and has been primarily identified as Sr₄Al₁₄O₅₁:Eu²⁺,Dy³⁺, a transient resultant with excess aluminum.