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.

The temperature dependence of the luminescence efficiency of M1.9Eu0.1Si5N8 (M=Ca, Sr, Ba) and Sr1.3Ca0.6Eu0.1Si5N8 (λexc=465 nm).Figure optionsDownload as PowerPoint slide