Method Of Decreasing The Synthesis Temperature For Strontium Aluminates Europium Dysprosium Phosphors

Aluminates long afterglow phosphors possess a great deal of good performances, for instance, high brightness, long persistence time, chemical stability and non-radiation pollution, and have extensive applicable prospect. At present, the synthesis temperature of strontium aluminates Europium Dysprosium (SAED) phosphors is higher than 1350℃generally, by means of solid phase method. In this article, we focused on the influences of synthesis temperature, flux and Ca²⁺ on luminescent properties of SAED phosphors, and synthesized high quality SAED phosphors at low temperature relatively.It is found that the effect of B₂O₃ content on luminescent properties of SAED phosphors depends on the synthesis temperature. At low synthesized temperature relatively, the increasing of B₂O₃ content induces better luminescent brightness and longer afterglow of samples, but at high synthesized temperature relatively, luminescent brightness and afterglow of samples get better first and worse later with the increasing of B₂O₃ content. The adding of B₂O₃ decreases the synthesis temperature of samples, and also, in favor of reducing the synthetic cost of SAED phosphor. Fluorescent spectral analysis indicates that excitation spectrum is in range of ultraviolet and visible light, and the emission spectrum has some change: when B₂O₃ content is low relatively, the emission peak of samples is quite near, when B₂O₃ content attains to 15%, there is obvious blue shift comparing with that of the non B₂O₃ content samples. For the samples with nominal composition of 2SrO·3Al₂O₃:Eu²⁺,Dy³⁺, the effect of adding Ca²⁺ on the luminance and lasting time of afterglow depends on the synthesis temperature and B₂O₃ content, at high synthesis temperature or with much B₂O₃, adding Ca²⁺ reduce the luminance and lasting time of afterglow, while at low synthesis temperature or with less B₂O₃, CaCO₃ can used as flux, and the adding of Ca²⁺ will increase the luminance and lasting time of afterglow. For 4SrO·7Al₂O₃:Eu²⁺,Dy³⁺, same result can be obtained with the adding of Ca²⁺. X-ray diffraction results indicate that no new phase can be observed. The excitation spectrum of samples for adding Ca²⁺ is a broadband spectrum between 200nm and 480nm, so this material can be easily excited by visible light. Yet, there is obviously red shift for the emission peak of the adding Ca²⁺ samples when comparing with that of no adding Ca²⁺ ones.At last, it is necessary to mention the 2SrO·3Al₂O₃:Eu²⁺,Dy³⁺ samples synthesized at 1250℃for 100 minutes, there are almost the same afterglow luminance and lasting time between the one adding 5% B₂O₃ and 5% CaCO₃ and the other one adding 12.5% B₂O₃.