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

Abstract

Doping β-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 β-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 78·28 wt-%Eu2+ doped β-Si6−zAlzOzN8−z (z = 2·1) 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 β-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 β-SiAlON phosphors in LED applications.

Carbothermal/aluminothermic reduction nitridation synthesis of ZrN–SiAlON refractory composites from zircon and bauxite: a comparative study of the reduction effect of reducers

“…Also, during the ARN process of zircon and bauxite, the following reactions could occur on the basis of the XRD analysis and previous studies besides reaction (10) [17,24,25]:…”

“…To reduce the cost of raw material, zircon mineral was selected as a raw material rather than ZrO 2 power in the present work. Besides, with regard to the preparation cost, the CRN was selected to synthesise ZrN-SiAlON composites because of the cheap price of reducers [10] and the common method of preparing SiAlON from bauxite [11]. In addition, many scientists [6,[12][13][14] had adopted CRN to synthesise ZrN with carbon black or carbon coke as reducers.…”