Distribution of Cerium Ions in Cerium‐Doped α′‐SiAlON and Its Effect on Grain Morphology

Cerium‐doped α′‐SiAlON material was prepared by spark plasma sintering at 1750°C under 30 MPa pressure for 10 min. Yttrium α′‐SiAlON seeds (1 wt%) were added to the starting powder mixture. Recent work showed that up to 45 wt% of α′‐SiAlON phases are formed in the present sintered ceramics. The material presented a microstructure, containing rodlike cerium‐doped α′‐SiAlON crystals. In this paper, transmission electron microscopy and energy dispersive spectroscopy examinations of the α′‐SiAlON grains are reported. The structural analyses revealed a high density of domain boundaries, within which larger amounts of cerium ions were segregated than in the matrix. The density of the domain boundaries was proportional to the amount of incorporated cerium ions. These structural defects eventually dominated the growth habits of the α′‐SiAlON crystals, by modifying the structure of the interstices at the boundary sites. The role of yttrium α′‐SiAlON seeds also is discussed in this paper.