Preparation and properties of Eu and Dy co-doped strontium aluminate long afterglow nanomaterials

The long afterglow nanomaterials of strontium aluminate co-doped by Eu and Dy have been synthesized by co-precipitation combined hydrothermal method. The effects of hydrothermal time, calcination time, pH value, the amount of aluminum nitrate, activator, co-activator and flux H3BO3 on the fluorescence properties of the product were investigated by means of single factor optimization experiment. Then the orthogonal experiment was employed to obtain the optimal synthesis conditions that are as follows: nDy/nEu = 2.5, tc = 2.5 h, nEu/nSr = 0.02, th = 8 h. Subsequently, the optimal synthesis conditions were verified by three repeated experiments, and the obtained products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and fluorescence spectrometer. The results showed that the synthesized target products all were the mixed crystal phase of SrAl2O4 and Sr4All4O25. The particles presented regular spherical-like with size ~ 100 nm. The dopants Eu and Dy were confirmed existed in the SrAl2O4 powders. The fluorescence and afterglow data of the target products were better than that in the orthogonal experiment scheme. The primary emission spectra band was in the range of 400-600 nm with characteristic peak located at ~ 460 nm corresponding to the transitions of Eu2+ ions from 4f65d→4f7, and the blue light can be observed by naked eyes. The similar fast-decaying and slow-decaying processes were displayed in all the afterglow curves, and the initial afterglow brightness of the target product is apparently higher than that of products synthesized by the orthogonal experiment. The synthesized target products, which show excellent long afterglow performance, present a great application prospects in the aspects of ceramics, plastics, arts and crafts, ink and coating.