Synthesis Research On Rare Earth Doped Strontium Aluminate Long Afterglow Luminescent Material

Aluminate long afterglow luminescent materials have broad application prospects, because of the properties of high brightness,long afterglow time,stable performance,and non-radiation.At present,solid-phase method is widely adopted to synthesis strontium europium dysprosium aluminate phosphors(SAED).The main limitation of this method is that the synthesis temperature is generally above 1350℃,which requires more expensive equipment,and also more energy consumption.Meanwhile,in such a high temperature,the particles are inclined to aggregate together which requires ball milling to reduce particle size.This would seriously deteriorate the luminescence properties,and consequently limit the application.So the most important thing of the synthesis processing is reducing the temperature and at the same time maintaining its excellent properties.We have carried on some previous work on Sr₄Al₁₄O₂₅:Eu,Dy before,which shows some possibility of synthesizing at 1250℃by adding 12.5%B₂O₃ as a kind of fluxing material.In order to confirm this and complete systemic research of it,more work should be done.Firstly,in this dissertation,we carried on systemic research on the effects of the amount of fluxing agent,synthesis temperature,synthesis time and proportion of Sr and Al,to the synthesis process and the performance of afterglow.The results indicate that the effect of B₂O₃ content on luminescent properties depends on the synthesis temperature.At low synthesis temperature,more content of B₂O₃ induce better luminescent brightness and longer afterglow time of samples,while at high synthesis temperature,less B₂O₃ content brings better properties.The adding of flux agent B₂O₃ in the synthesis process will result in change of emission color of the material,which is originate from its assistance to the sintering process and influence to the phase of the outcome materials.X-ray diffraction shows that,when no or little B₂O₃ is added,and lack of complete reaction,the material synthesized atl250℃consists of three kinds of substances,which are mainly SrAl₂O₄ that emits yellow-green color,and some Sr₄Al₁₄O₂₅,and a kind of excess alumina phase.With the increasing of B₂O₃ content,the solid reaction was more thoroughly processed and the matrix crystallized better,which result in single phase of stable blue-green emitting Sr₄Al₁₄O₂₅.The long lasting blue-emitting luminescent material, Sr₄Al₁₄O₂₅:Eu,Dy,with long after-glow of 24h by machine and 50h by eyes,has been synthesized at 1250℃,5h,and with flux of 12.5%B₂O₃,which meets the requiring of the commercial application.Then,our goal of lowering the synthesis temperature but not lowering the properties of aluminates is achieved.Secondly,in this dissertation the research on the effect of synthesis temperature, amount of fluxing agent and synthesis time on the performance of afterglow of SrAl₂O₄:Eu,Dy,another kind of important aluminate long afterglow material,was also carried on.SrAl₂O₄:Eu,Dy with good performance of afterglow has been synthesized at 1250℃,3h,and with flux agent of 12.5%B₂O₃.The research work on Sr₄Al₁₄O₂₅:Eu,Dy and SrAl₂O₄:Eu,Dy,two main kinds of long afterglow luminescent aluminate,indicates that,by adding 12.5%B₂O₃ as the flux agent,the synthesis temperature can be lower down,while the properties remain excellent at the same time.This reduces the synthesis cost and energy consumption,and obviously place better base for future research and develop on application.