Preparation of single phase nano-sized β-SiAlON powders by nitridation of silica–alumina gel in ammonia

β-SiAlON powder was prepared from silica–alumina gel and by heat-treatment in ammonia. Element analysis, X-ray diffraction, magic-angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy were used to characterize the powder. It was found that nitridation reactions took place at 1100 °C and β-SiAlON began to crystallize at 1300 °C with mullite, O-SiAlON and χ-SiAlON as the intermediate phases. Nano-sized single phase β-SiAlON powder was obtained after heating at 1350 °C for 3 h.