The effect of replacement of Sr by Ca on the structural and luminescence properties of the red-emitting Sr2Si5N8:Eu2+ LED conversion phosphor

The influence of the replacement of Sr by Ca on structural and luminescence properties of Eu2+-doped Sr2Si5N8 is reported. The Rietveld refinement of the powder X-ray diffraction data shows that the Ca2+ ion preferentially occupies the larger Sr site in Sr2Si5N8:Eu2+. Although the excitation spectrum is hardly modified, the position of the emission band of Eu2+ can be tailored through partial replacement of Sr by Ca in Sr2Si5N8:Eu2+, resulting in red-emission shifting from 620 to 643 nm. Furthermore, (Sr, Ca)2Si5N8:Eu2+ shows high potential as a conversion phosphor for white-light LED applications due to similar absorption, conversion efficiency and thermal quenching behaviour for 465 nm excitation after the introduction of the Ca ion.