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

Posted on:2008-07-06Degree:MasterType:Thesis
Country:ChinaCandidate:T R GuFull Text:PDF
GTID:2121360212995660Subject:Materials science
Abstract/Summary:PDF Full Text Request
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.
Keywords/Search Tags:Strontium aluminates europium dysprosium, long afterglow luminescent material, flux, B2O3, CaCO3
PDF Full Text Request
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