Crystal Phase and Phonon Densities of States of β'‐SiAION Ceramics, Si 6‐z Al z O z N 8‐z (0 ≤ z ≤ 4)

The crystal structure and phonon densities of states (DOS) of β‐SiAlON ceramics, Si 6 _ z Al z O z N 8‐z (0 < z < 4), prepared by a novel slipcast method, are studied by neutron‐scattering techniques. The samples with z < 4 form a single‐phase solid solution of Si‐Al‐O‐N isostructural to β‐Si 3 N 4 (space group P 6 3 /m). A consistent preferential occupation of the 2c sites by oxygen atoms and the 6 h sites by nitrogen atoms exists within this structure. The phonon DOS of β'‐SiAlON displays phonon bands at ∼50 and 115 meV. These features are considerably broader than the corresponding ones in β‐Si 3 N 4 powder.