Photoluminescence and thermal quenching properties of tunable green-emitting oxynitride (CaxSr1–x)6Si25.6Al6.4N41.6O4.4:Eu2+ phosphors

Green emitting Eu2+ doped (CaxSr1–x)6Si25.6Al6.4N41.6O4.4 phosphors with x value ranging from 0 to 0.1 were synthesized by the solid state reaction method under nitrogen atmosphere. The X-ray diffraction (XRD) patterns of the phosphors with different Ca2+ concentrations indicated that pure sialon phases were obtained. Crystal structure of these sialon phases was estimated to be a commensurate composite network stacking by two different types of layers. Intense and tunable green emissions with a slight red shift from 515 to 520 nm were observed with varying Ca/Sr ratios. The emission intensity decreased gradually because of the increase of the crystal splitting effect. Thermal quenching properties of the phosphors with different Ca2+ saturation were also discussed. The thermal stability became worse as more Ca2+ ions substituted for Sr2+ ions according to a larger Stokes shift. The solid solution phosphors could be a promising candidate for white LEDs for their interesting photoluminescence properties when the thermal stability would be improved.

Graphical AbstractCrystal structure of Sr6Si25.6Al6.4 N41.6O4.4 viewing along a axisFigure optionsDownload as PowerPoint slide