Influence of calcination temperature on luminescent properties of Sr 3Al 2O 6:Eu 2+, Dy 3+ phosphors prepared by sol–gel-combustion processing

Abstract

The detailed preparation process of Eu 2+ and Dy 3+ ion co-doped Sr 3Al 2O 6 phosphor powders with red long afterglow by sol–gel-combustion method in the reducing atmosphere is reported. X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy are used to investigate the effects of synthesis temperature on the crystal characteristics, morphology and luminescent properties of the as-synthesized Sr 3Al 2O 6:Eu 2+, Dy 3+ phosphors. The results reveal that Sr 3Al 2O 6 crystallizes completely when the combustion ash is sintered at 1200 °C. The excitation and the emission spectra indicate that the excitation broad-band lies chiefly in visible range and the phosphor powders emit strong light at 618 nm under the excitation of 472 nm. The light intensity and the light-lasting time of Sr 3Al 2O 6:Eu 2+, Dy 3+ phosphors are increased when increasing the calcination temperatures from 1050 to 1200 °C. The afterglow of Sr 3Al 2O 6:Eu 2+, Dy 3+ phosphors sintered at 1200 °C lasts for over 600 s when the excited source is cut off. The red emission mechanism is discussed according to the effect of nephelauxetic and crystal field on the 4f 65d 1 → 4f 7 transition of the Eu 2+ ions.