Structure, luminescence and thermal quenching properties of Eu doped Sr2−xBaxSi5N8 red phosphors

Abstract

Eu2+ doped Sr2-xBaxSi5N8 phosphors were synthesized at 1610℃ for 4h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610nm to 585nm under the excitation of 460nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasing x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu2+ doped Sr2-xBaxSi5N8 is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs).