β′-sialon powder was synthesised using kaolin of different chemical compositions by carbothermal reduction–nitridation. The products were analysed by X-ray diffraction (XRD) and differential thermal analysis (DTA). The results show that when the ratio m(SiO2)/m(Al2O3) is large, the Z value is small, and when the ratio m(SiO2)/m(Al2O3) decreases, the Z value tends to increase. Single crystal phase β-sialon powder was obtained when the m(SiO2)/m(Al2O3) ratio in kaolin was around 1.55.
