Eu, Dy co-doped SrAl2O4 phosphors prepared by sol-gel-combustion processing

摘要

SrAl2O4:Eu~(2+), Dy~(3+) powders were synthesized by sol-gel-combustion process using metal nitrates as the source of metal ions and citric acid as a chelating agent of metal ions. The amounts of citric acid in mole were two times those of the metal ions. By tracing the formation process of the sol-gel, it is found that decreasing the amount of NO_3~- in the solution is necessary for the formation of transparent sol and gel, and the dropping of ethanol into the precursor solution can decrease the amount of NO_3~- in the solution. By combusting citrate sol at 600 °C, followed by heating the resultant combustion ash at 1,100-1,300 °C in a weak reductive atmosphere containing active carbon, SrAl2O4:Eu~(2+), Dy~(3+) phosphors can prepared. X-ray diffraction, Thermogravimetry-differential thermal analysis, scanning electron microscopy and fluorescence spectrophotometer were used to investigate the formation process and luminescent properties of the as-synthesized SrAl2O4:Eu~(2+), Dy~(3+). The results reveal that the SrAl2O4 crystallizes completely when the combustion ash was sintered at 1,200-1,300 °C. The excitation and emission spectra indicate that excitation broadband mainly lies in a visible range and the phosphors emit strong light at 510 nm under the excitation of 348 nm. The afterglow of phosphors lasts for over 10 h when the excited source is cut off.