Tailoring of phase assemblage and grain morphology of (Nd,Dy)-containing SiAlON powders prepared by combustion synthesis

(Nd,Dy)-containing SiAlON powders were prepared by combustion synthesis, where it was proved that the phase assemblage and grain morphology of final products could be tailored by controlling the relative contents of the two rare-earth elements. When the molar ratio of Dy/(Nd + Dy) was increased, the phase content of α-SiAlON was promoted and β-SiAlON was reduced. At the same time, the grain morphology of combustion products varied from elongated prismatic crystals to fine isotropic grains. It was also found that the lattice parameters of both α- and β-SiAlON were affected by Dy/(Nd + Dy) ratios. The experimental results were discussed by considering the different ability of Dy³⁺ and Nd³⁺ to stabilize α-SiAlON structure.