Study On Preparation And Photoluminescence Characteristics Of Strontium Aluminates Long Afterglow Materials

This paper discussed the process of coated-precipitation for preparing SrAl2O4:Eu,Dy long afterglow photoluminescence materials. The Sr2+and rare earth ions were deposited on Al(OH)3 substrate by H2C2O4 as precipitator at pH value between 6～6.5 and at 40-45℃. The ratio of the precipitation of Eu3+ and Sr2+ was investigated by ICP , the phase compositions of precursor and production were analyzed by XRD, the particle morphology and grain diameter of the powders inspected by SEM, the uniformity of the coated precursor was examined by EDS, the processes of heat treatment were studied by the TG-DTA and XRD. Excitation and emission spectrum and decay characteristic of afterglow of the phosphor calcined with weak reducing atmosphere were investigated.The precipitator and pH value of solution affect the production effiency. strontium aluminates crystals were formed directly from amorphous state without any intermediate oxides crystals; the SrAl2O4 can be synthesized at low temperatures and the heating temperature is deduced by about 100 to 150 centigrade compared with the solid-state reaction. It is discoved that the emission intensity of phosphors increased firstly then decreased with the content of Eu2+ ions. The quenching concentration of the phosphors is 2mol% and the quenching mechanism is proved as dipole-dipole interaction. It is proved that the fluorescent decay process includes fast decay and consequently slow decay process due to the two different existent trapping levels. It was found that Dy3+ played an important role in the system resulted in different decay time.Influence of a little H3BO3 on reaction at high temperature and luminescent properties were investigated. It showed that phosphors can be calcined at lower temperature with a little H3BO3 added as flux.