A novel approach on the synthesis of beta-SiAlON:Eu2+ phosphors from kaolin through carbothermal reduction and nitridation (CRN) route

Abstract

Doping beta-SiAlON crystal structure with rare earths leads to a superior tuneable luminescence properties for light emitting diodes (LEDs). However, the widely used conventional methods require high purity starting powders and time consuming processes. Here, a new approach to synthesise Eu2+ activated beta-SiAlON phosphors from kaolin through carbothermal reduction and nitridation route was introduced. The Rietveld refinement on powder X-ray diffraction method and scanning electron microscopy with energy dispersive X-ray spectroscopy analyses showed that 78 center dot 28 wt% Eu2+ doped beta-Si6-zAlzOzN8-z (z=2 center dot 1) was successfully obtained. Photoluminescence examinations under the 267 nm excitation revealed two distinct broad emission peaks: maxima at around 415 nm (violet) and 540 nm(green). Transmission electron microscopy observations demonstrated the incorporation of Eu2+ ions into beta-SiAlON grains giving the observed violet and green emissions. It is anticipated that this study paves a way for cost effective synthesis of rare earth doped single phase beta-SiAlON phosphors in LED applications.