Synthesis and Optical Characterization of M-α-Sialon (M=Ca, Ba, Sr) Doped by Europium

Abstract

Oxynitrides compounds are interesting for white LED industry because more covalent matrix's bonds in comparison to oxides enable to obtain higher color temperature of wLED. The Sialon's luminescence material doped by rare earth ions with high mechanical and chemical resistance and a broad emission band may become an alternative for garnet phosphors. The goal of the study was to investigate influence of divalent stabilizing cations on luminescence properties of M-α-Sialon doped with Eu2+ in order to estimate its potential for YAG:Ce replacement in WLEDs. The compound of general formula EuxM1-xSi9,6Al2,4O0,8N15,2, where M=Ca, Ba, Sr, was prepared by the solid state reaction method from the mixture of the relevant oxides, nitrides and carbonates. Synthesis was carried out at the temperature of 1650°C for 4 h in a reduction atmosphere (N2+CO). The structure and morphology of obtained powders were analyzed by XRD and SEM/EDS methods, respectively. Optical properties were investigated by excitation, emission and reflection spectra and compared to photoluminescence properties of standard YAG:Ce. The obtained specimens show the significant effect of synthesis parameters on the phase composition and intensity of emission of M-α-Sialon:Eu2+ powder.