The Preparation And Properties Of Rare Earth Doped Strontium Aluminate Long Afterglow Phosphor

The long afterglow phosphor of strontium aluminate doped with rare earth, which possesses the advantages of nontoxic, energy-saving and environmental protection, have been widely applied in the fields of security alerts, paint industries, textile materials and so on.It attracted the research interest of scientists at home and abroad. In this paper, the long afterglow phosphor of strontium aluminate doped with rare earth were prepared by co-precipitation-hydrothermal ways and sol-gel method, respectively. Furthermore, their reaction conditions were optimized by means of single factor experiments and orthogonal experiment. The main research work includes the following two aspects.(1) The long afterglow phosphor of strontium aluminate doped with rare earth was obtained by co-precipitation-hydrothermal ways, using ammonia and ammonium carbonate as co-precipitant, respectively. The influence of the solution pH, the burning temperature, the dosage of activator dosage, auxiliary activator and flux on the luminescent properties of the target product was investigated. Based on the single factor experiments, we optimized the preparation technology by orthogonal experiment. The optimal reaction conditions for ammonia as co-precipitation were with the activator dosage (Eu/Sr) as0.03, the auxiliary activator dosage (Dy/Eu) as1:1, the dosage of boric acid flux (m/W) as0.08, the pH value as8. The optimal reaction conditions for ammonium carbonate as co-precipitation were with the activator dosage (Eu/Sr) as0.01, the auxiliary activator dosage (Dy/Eu) as1:1, the dosage of boric acid flux (m/W) as0.1, the pH value as8. The targeted products were prepared on the optimized reaction condition, and characterized with XRD (X-ray diffraction), SEM (scanning electron microscope), FSA (fluorescence spectrum analysis), and PLDA (Phosphorescence Lifetime decay analysis). The experimental results showed that the optimal excitation wavelengths of the products obtained using both ammonium and ammonium carbonate as co-precipitation were around360.0nm. The product co-precipitated by ammonium was Sr4Al14O25crystal form orthorhombic system, consisting of the nano-rod with50nm diameter and200nm length, and emited490.0nm fluorescence, lasted35s phosphorescence decay lifetime. The product co-precipitated by ammonium carbonate was Sr4Al14O25crystal form orthorhombic system, consisting of the nano-plate with thickness of50nm, and emited460.0nm of fluorescence, lasted15s phosphorescence decay lifetime.(2) The long afterglow phosphor of strontium aluminate doped with rare earth was prepared by sol-gel ways using citric acid and polyethylene glycol as complexing agent. The influence of the burning temperature, the dosage of activator, auxiliary activator and flux on the luminescent properties of the target product was investigated. Based on the single factor experiments, we optimized the preparation technology by orthogonal experiment. The optimal reaction conditions for citric acid as complexing agent were with the activator dosage (Eu/Sr) as0.02, the auxiliary activator dosage (Dy/Eu) as1:3, the dosage of boric acid flux (MB/W) as0.08, the burning temperature as1200℃. The optimal reaction conditions for polyethylene glycol as complexing agent were with the activator dosage (Eu/Sr) as0.03, the auxiliary activator dosage (Dy/Eu) as1:2, the dosage of boric acid flux (MB/W) as0.1, the burning temperature as1200℃. The targeted products were prepared on the optimized reaction condition, and characterized with XRD, SEM, FSA, and PLDA. The experimental results showed that the optimal excitation and emission wavelengths of the products obtained using both citric acid and polyethylene glycol as complexing agent were around360.0nm and511.5nm, respectively. The product obtained by citric acid and polyethylene glycol were SrAl2O4crystal form monoclinic system, showed the morphology of nano-grains with diameter around50nm. The phosphorescence decay lifetime was14s and25s for product obtained by citric acid and polyethylene glycol as complexing agent,respectively.